Package: odoo14-addon-fastapi
This addon provides the basis to smoothly integrate theFastAPIframework into Odoo.This integration allows you to use all the goodies fromFastAPIto build custom
APIs for your Odoo server based on standard Python type hints.What is building an API?An API is a set of functions that can be called from the outside world. The
goal of an API is to provide a way to interact with your application from the
outside world without having to know how it works internally. A common mistake
when you are building an API is to expose all the internal functions of your
application and therefore create a tight coupling between the outside world and
your internal datamodel and business logic. This is not a good idea because it
makes it very hard to change your internal datamodel and business logic without
breaking the outside world.When you are building an API, you define a contract between the outside world
and your application. This contract is defined by the functions that you expose
and the parameters that you accept. This contract is the API. When you change
your internal datamodel and business logic, you can still keep the same API
contract and therefore you don’t break the outside world. Even if you change
your implementation, as long as you keep the same API contract, the outside
world will still work. This is the beauty of an API and this is why it is so
important to design a good API.A good API is designed to be stable and to be easy to use. It’s designed to
provide high-level functions related to a specific use case. It’s designed to
be easy to use by hiding the complexity of the internal datamodel and business
logic. A common mistake when you are building an API is to expose all the internal
functions of your application and let the oustide world deal with the complexity
of your internal datamodel and business logic. Don’t forget that on a transactional
point of view, each call to an API function is a transaction. This means that
if a specific use case requires multiple calls to your API, you should provide
a single function that does all the work in a single transaction. This why APIs
methods are called high-level and atomic functions.Table of contentsUsageUsageWhat’s building an API with fastapi?FastAPI is a modern, fast (high-performance), web framework for building APIs
with Python 3.7+ based on standard Python type hints. This addons let’s you
keep advantage of the fastapi framework and use it with Odoo.Before you start, we must define some terms:App: A FastAPI app is a collection of routes, dependencies, and other
components that can be used to build a web application.Router: A router is a collection of routes that can be mounted in an
app.Route: A route is a mapping between an HTTP method and a path, and
defines what should happen when the user requests that path.Dependency: A dependency is a callable that can be used to get some
information from the user request, or to perform some actions before the
request handler is called.Request: A request is an object that contains all the information
sent by the user’s browser as part of an HTTP request.Response: A response is an object that contains all the information
that the user’s browser needs to build the result page.Handler: A handler is a function that takes a request and returns a
response.Middleware: A middleware is a function that takes a request and a
handler, and returns a response.The FastAPI framework is based on the following principles:Fast: Very high performance, on par with NodeJS and Go (thanks to Starlette
and Pydantic). [One of the fastest Python frameworks available]Fast to code: Increase the speed to develop features by about 200% to 300%.Fewer bugs: Reduce about 40% of human (developer) induced errors.Intuitive: Great editor support. Completion everywhere. Less time
debugging.Easy: Designed to be easy to use and learn. Less time reading docs.Short: Minimize code duplication. Multiple features from each parameter
declaration. Fewer bugs.Robust: Get production-ready code. With automatic interactive documentation.Standards-based: Based on (and fully compatible with) the open standards
for APIs: OpenAPI (previously known as Swagger) and JSON Schema.Open Source: FastAPI is fully open-source, under the MIT license.The first step is to install the fastapi addon. You can do it with the
following command:$ pip install odoo-addon-fastapiOnce the addon is installed, you can start building your API. The first thing
you need to do is to create a new addon that depends on ‘fastapi’. For example,
let’s create an addon calledmy_demo_api.Then, you need to declare your app by defining a model that inherits from
‘fastapi.endpoint’ and add your app name into the app field. For example:fromodooimportfields,modelsclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})The‘fastapi.endpoint’model is the base model for all the endpoints. An endpoint
instance is the mount point for a fastapi app into Odoo. When you create a new
endpoint, you can define the app that you want to mount in the‘app’field
and the path where you want to mount it in the‘path’field.figure:: static/description/endpoint_create.pngFastAPI EndpointThanks to the‘fastapi.endpoint’model, you can create as many endpoints as
you want and mount as many apps as you want in each endpoint. The endpoint is
also the place where you can define configuration parameters for your app. A
typical example is the authentication method that you want to use for your app
when accessed at the endpoint path.Now, you can create your first router. For that, you need to define a global
variable into your fastapi_endpoint module called for example ‘demo_api_router’fromfastapiimportAPIRouterfromodooimportfields,modelsclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})# create a routerdemo_api_router=APIRouter()To make your router available to your app, you need to add it to the list of routers
returned by the_get_fastapi_routersmethod of your fastapi_endpoint model.fromfastapiimportAPIRouterfromodooimportapi,fields,modelsclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})def_get_fastapi_routers(self):ifself.app=="demo":return[demo_api_router]returnsuper()._get_fastapi_routers()# create a routerdemo_api_router=APIRouter()Now, you can start adding routes to your router. For example, let’s add a route
that returns a list of partners.importsysifsys.version_info>=(3,9):fromtypingimportAnnotatedelse:fromtyping_extensionsimportAnnotatedfromfastapiimportAPIRouterfrompydanticimportBaseModelfromodooimportapi,fields,modelsfromodoo.apiimportEnvironmentfromodoo.addons.fastapi.dependenciesimportodoo_envclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})def_get_fastapi_routers(self):ifself.app=="demo":return[demo_api_router]returnsuper()._get_fastapi_routers()# create a routerdemo_api_router=APIRouter()classPartnerInfo(BaseModel):name:stremail:str@demo_api_router.get("/partners",response_model=list[PartnerInfo])defget_partners(env:Annotated[Environment,Depends(odoo_env)])->list[PartnerInfo]:return[PartnerInfo(name=partner.name,email=partner.email)forpartnerinenv["res.partner"].search([])]Now, you can start your Odoo server, install your addon and create a new endpoint
instance for your app. Once it’s done click on the docs url to access the
interactive documentation of your app.Before trying to test your app, you need to define on the endpoint instance the
user that will be used to run the app. You can do it by setting the‘user_id’field. This information is the most important one because it’s the basis for
the security of your app. The user that you define in the endpoint instance
will be used to run the app and to access the database. This means that the
user will be able to access all the data that he has access to in Odoo. To ensure
the security of your app, you should create a new user that will be used only
to run your app and that will have no access to the database.<recordid="my_demo_app_user"model="res.users"context="{'no_reset_password': True, 'no_reset_password': True}"><fieldname="name">MyDemoEndpointUser</field><fieldname="login">my_demo_app_user</field><fieldname="groups_id"eval="[(6, 0, [])]"/></record>At the same time you should create a new group that will be used to define the
access rights of the user that will run your app. This group should imply
the predefined group‘FastAPI Endpoint Runner’. This group defines the
minimum access rights that the user needs to:access the endpoint instance it belongs toaccess to its own user recordaccess to the partner record that is linked to its user record<recordid="my_demo_app_group"model="res.groups"><fieldname="name">MyDemoEndpointGroup</field><fieldname="users"eval="[(4, ref('my_demo_app_user'))]"/><fieldname="implied_ids"eval="[(4, ref('fastapi.group_fastapi_endpoint_runner'))]"/></record>Now, you can test your app. You can do it by clicking on the ‘Try it out’ button
of the route that you have defined. The result of the request will be displayed
in the ‘Response’ section and contains the list of partners.NoteThe‘FastAPI Endpoint Runner’group ensures that the user cannot access any
information others than the 3 ones mentioned above. This means that for every
information that you want to access from your app, you need to create the
proper ACLs and record rules. (seeManaging security into the route handlers)
It’s a good practice to use a dedicated user into a specific group from the
beginning of your project and in your tests. This will force you to define
the proper security rules for your endoints.Dealing with the odoo environmentThe‘odoo.addons.fastapi.dependencies’module provides a set of functions that you can use
to inject reusable dependencies into your routes. For example, the‘odoo_env’function returns the current odoo environment. You can use it to access the
odoo models and the database from your route handlers.importsysifsys.version_info>=(3,9):fromtypingimportAnnotatedelse:fromtyping_extensionsimportAnnotatedfromodoo.apiimportEnvironmentfromodoo.addons.fastapi.dependenciesimportodoo_env@demo_api_router.get("/partners",response_model=list[PartnerInfo])defget_partners(env:Annotated[Environment,Depends(odoo_env)])->list[PartnerInfo]:return[PartnerInfo(name=partner.name,email=partner.email)forpartnerinenv["res.partner"].search([])]As you can see, you can use the‘Depends’function to inject the dependency
into your route handler. The‘Depends’function is provided by the‘fastapi’framework. You can use it to inject any dependency into your route
handler. As your handler is a python function, the only way to get access to
the odoo environment is to inject it as a dependency. The fastapi addon provides
a set of function that can be used as dependencies:‘odoo_env’: Returns the current odoo environment.‘fastapi_endpoint’: Returns the current fastapi endpoint model instance.‘authenticated_partner’: Returns the authenticated partner.‘authenticated_partner_env’: Returns the current odoo environment with the
authenticated_partner_id into the context.By default, the‘odoo_env’and‘fastapi_endpoint’dependencies are
available without extra work.NoteEven if ‘odoo_env’ and ‘authenticated_partner_env’ returns the current odoo
environment, they are not the same. The ‘odoo_env’ dependency returns the
environment without any modification while the ‘authenticated_partner_env’
adds the authenticated partner id into the context of the environment. As it will
be explained in the sectionManaging security into the route handlersdedicated
to the security, the presence of the authenticated partner id into the context
is the key information that will allow you to enforce the security of your endpoint
methods. As consequence, you should always use the ‘authenticated_partner_env’
dependency instead of the ‘odoo_env’ dependency for all the methods that are
not public.The dependency injection mechanismThe‘odoo_env’dependency relies on a simple implementation that retrieves
the current odoo environment from ContextVar variable initialized at the start
of the request processing by the specific request dispatcher processing the
fastapi requests.The‘fastapi_endpoint’dependency relies on the ‘dependency_overrides’ mechanism
provided by the‘fastapi’module. (see the fastapi documentation for more
details about the dependency_overrides mechanism). If you take a look at the
current implementation of the‘fastapi_endpoint’dependency, you will see
that the method depends of two parameters:‘endpoint_id’and‘env’. Each
of these parameters are dependencies themselves.deffastapi_endpoint_id()->int:"""This method is overriden by default to make the fastapi.endpoint record
    available for your endpoint method. To get the fastapi.endpoint record
    in your method, you just need to add a dependency on the fastapi_endpoint method
    defined below
    """deffastapi_endpoint(_id:Annotated[int,Depends(fastapi_endpoint_id)],env:Annotated[Environment,Depends(odoo_env)],)->"FastapiEndpoint":"""Return the fastapi.endpoint record"""returnenv["fastapi.endpoint"].browse(_id)As you can see, one of these dependencies is the‘fastapi_endpoint_id’dependency and has no concrete implementation. This method is used as a contract
that must be implemented/provided at the time the fastapi app is created.
Here comes the power of the dependency_overrides mechanism.If you take a look at the‘_get_app’method of the‘FastapiEndpoint’model,
you will see that the‘fastapi_endpoint_id’dependency is overriden by
registering a specific method that returns the id of the current fastapi endpoint
model instance for the original method.def_get_app(self)->FastAPI:app=FastAPI(**self._prepare_fastapi_endpoint_params())forrouterinself._get_fastapi_routers():app.include_router(prefix=self.root_path,router=router)app.dependency_overrides[dependencies.fastapi_endpoint_id]=partial(lambdaa:a,self.id)This kind of mechanism is very powerful and allows you to inject any dependency
into your route handlers and moreover, define an abstract dependency that can be
used by any other addon and for which the implementation could depend on the
endpoint configuration.The authentication mechanismTo make our app not tightly coupled with a specific authentication mechanism,
we will use the‘authenticated_partner’dependency. As for the‘fastapi_endpoint’this dependency depends on an abstract dependency.When you define a route handler, you can inject the‘authenticated_partner’dependency as a parameter of your route handler.fromodoo.addons.base.models.res_partnerimportPartner@demo_api_router.get("/partners",response_model=list[PartnerInfo])defget_partners(env:Annotated[Environment,Depends(odoo_env)],partner:Annotated[Partner,Depends(authenticated_partner)])->list[PartnerInfo]:return[PartnerInfo(name=partner.name,email=partner.email)forpartnerinenv["res.partner"].search([])]At this stage, your handler is not tied to a specific authentication mechanism
but only expects to get a partner as a dependency. Depending on your needs, you
can implement different authentication mechanism available for your app.
The fastapi addon provides a default authentication mechanism using the
‘BasicAuth’ method. This authentication mechanism is implemented in the‘odoo.addons.fastapi.dependencies’module and relies on functionalities provided
by the‘fastapi.security’module.defauthenticated_partner(env:Annotated[Environment,Depends(odoo_env)],security:Annotated[HTTPBasicCredentials,Depends(HTTPBasic())],)->"res.partner":"""Return the authenticated partner"""partner=env["res.partner"].search([("email","=",security.username)],limit=1)ifnotpartner:raiseHTTPException(status_code=status.HTTP_401_UNAUTHORIZED,detail="Invalid authentication credentials",headers={"WWW-Authenticate":"Basic"},)ifnotpartner.check_password(security.password):raiseHTTPException(status_code=status.HTTP_401_UNAUTHORIZED,detail="Invalid authentication credentials",headers={"WWW-Authenticate":"Basic"},)returnpartnerAs you can see, the‘authenticated_partner’dependency relies on the‘HTTPBasic’dependency provided by the‘fastapi.security’module.
In this dummy implementation, we just check that the provided credentials
can be used to authenticate a user in odoo. If the authentication is successful,
we return the partner record linked to the authenticated user.In some cases you could want to implement a more complex authentication mechanism
that could rely on a token or a session. In this case, you can override the‘authenticated_partner’dependency by registering a specific method that
returns the authenticated partner. Moreover, you can make it configurable on
the fastapi endpoint model instance.To do it, you just need to implement a specific method for each of your
authentication mechanism and allows the user to select one of these methods
when he creates a new fastapi endpoint. Let’s say that we want to allow the
authentication by using an api key or via basic auth. Since basic auth is already
implemented, we will only implement the api key authentication mechanism.fromfastapi.securityimportAPIKeyHeaderdefapi_key_based_authenticated_partner_impl(api_key:Annotated[str,Depends(APIKeyHeader(name="api-key",description="In this demo, you can use a user's login as api key.",))],env:Annotated[Environment,Depends(odoo_env)],)->Partner:"""A dummy implementation that look for a user with the same login
    as the provided api key
    """partner=env["res.users"].search([("login","=",api_key)],limit=1).partner_idifnotpartner:raiseHTTPException(status_code=status.HTTP_401_UNAUTHORIZED,detail="Incorrect API Key")returnpartnerAs for the ‘BasicAuth’ authentication mechanism, we also rely on one of the native
security dependency provided by the‘fastapi.security’module.Now that we have an implementation for our two authentication mechanisms, we
can allows the user to select one of these authentication mechanisms by adding
a selection field on the fastapi endpoint model.fromodooimportfields,modelsclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})demo_auth_method=fields.Selection(selection=[("api_key","Api Key"),("http_basic","HTTP Bacic")],string="Authenciation method",)NoteA good practice is to prefix specific configuration fields of your app with
the name of your app. This will avoid conflicts with other app when the
‘fastapi.endpoint’ model is extended for other ‘app’.Now that we have a selection field that allows the user to select the
authentication method, we can use the dependency override mechanism to
provide the right implementation of the‘authenticated_partner’dependency
when the app is instantiated.fromodoo.addons.fastapi.dependenciesimportauthenticated_partnerclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})demo_auth_method=fields.Selection(selection=[("api_key","Api Key"),("http_basic","HTTP Bacic")],string="Authenciation method",)def_get_app(self)->FastAPI:app=super()._get_app()ifself.app=="demo":# Here we add the overrides to the authenticated_partner_impl method# according to the authentication method configured on the demo appifself.demo_auth_method=="http_basic":authenticated_partner_impl_override=(authenticated_partner_from_basic_auth_user)else:authenticated_partner_impl_override=(api_key_based_authenticated_partner_impl)app.dependency_overrides[authenticated_partner_impl]=authenticated_partner_impl_overridereturnappTo see how the dependency override mechanism works, you can take a look at the
demo app provided by the fastapi addon. If you choose the app ‘demo’ in the
fastapi endpoint form view, you will see that the authentication method
is configurable. You can also see that depending on the authentication method
configured on your fastapi endpoint, the documentation will change.NoteAt time of writing, the dependency override mechanism is not supported by
the fastapi documentation generator. A fix has been proposed and is waiting
to be merged. You can follow the progress of the fix ongithubManaging configuration parameters for your appAs we have seen in the previous section, you can add configuration fields
on the fastapi endpoint model to allow the user to configure your app (as for
any odoo model you extend). When you need to access these configuration fields
in your route handlers, you can use the‘odoo.addons.fastapi.dependencies.fastapi_endpoint’dependency method to retrieve the ‘fastapi.endpoint’ record associated to the
current request.frompydanticimportBaseModel,Fieldfromodoo.addons.fastapi.dependenciesimportfastapi_endpointclassEndpointAppInfo(BaseModel):id:strname:strapp:strauth_method:str=Field(alias="demo_auth_method")root_path:strclassConfig:orm_mode=True@demo_api_router.get("/endpoint_app_info",response_model=EndpointAppInfo,dependencies=[Depends(authenticated_partner)],)asyncdefendpoint_app_info(endpoint:Annotated[FastapiEndpoint,Depends(fastapi_endpoint)],)->EndpointAppInfo:"""Returns the current endpoint configuration"""# This method show you how to get access to current endpoint configuration# It also show you how you can specify a dependency to force the security# even if the method doesn't require the authenticated partner as parameterreturnEndpointAppInfo.from_orm(endpoint)Some of the configuration fields of the fastapi endpoint could impact the way
the app is instantiated. For example, in the previous section, we have seen
that the authentication method configured on the ‘fastapi.endpoint’ record is
used in order to provide the right implementation of the‘authenticated_partner’when the app is instantiated. To ensure that the app is re-instantiated when
an element of the configuration used in the instantiation of the app is
modified, you must override the‘_fastapi_app_fields’method to add the
name of the fields that impact the instantiation of the app into the returned
list.classFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"app:str=fields.Selection(selection_add=[("demo","Demo Endpoint")],ondelete={"demo":"cascade"})demo_auth_method=fields.Selection(selection=[("api_key","Api Key"),("http_basic","HTTP Bacic")],string="Authenciation method",)@api.modeldef_fastapi_app_fields(self)->List[str]:fields=super()._fastapi_app_fields()fields.append("demo_auth_method")returnfieldsDealing with languagesThe fastapi addon parses the Accept-Language header of the request to determine
the language to use. This parsing is done by respecting theRFC 7231 specification. That means that
the language is determined by the first language found in the header that is
supported by odoo (with care of the priority order). If no language is found in
the header, the odoo default language is used. This language is then used to
initialize the Odoo’s environment context used by the route handlers. All this
makes the management of languages very easy. You don’t have to worry about. This
feature is also documented by default into the generated openapi documentation
of your app to instruct the api consumers how to request a specific language.How to extend an existing appWhen you develop a fastapi app, in a native python app it’s not possible
to extend an existing one. This limitation doesn’t apply to the fastapi addon
because the fastapi endpoint model is designed to be extended. However, the
way to extend an existing app is not the same as the way to extend an odoo model.First of all, it’s important to keep in mind that when you define a route, you
are actually defining a contract between the client and the server. This
contract is defined by the route path, the method (GET, POST, PUT, DELETE,
etc.), the parameters and the response. If you want to extend an existing app,
you must ensure that the contract is not broken. Any change to the contract
will respect theLiskov substitution principle. This means
that the client should not be impacted by the change.What does it mean in practice? It means that you can’t change the route path
or the method of an existing route. You can’t change the name of a parameter
or the type of a response. You can’t add a new parameter or a new response.
You can’t remove a parameter or a response. If you want to change the contract,
you must create a new route.What can you change?You can change the implementation of the route handler.You can override the dependencies of the route handler.You can add a new route handler.You can extend the model used as parameter or as response of the route handler.Let’s see how to do that.Changing the implementation of the route handlerLet’s say that you want to change the implementation of the route handler‘/demo/echo’. Since a route handler is just a python method, it could seems
a tedious task since we are not into a model method and therefore we can’t
take advantage of the Odoo inheritance mechanism.However, the fastapi addon provides a way to do that. Thanks to the‘odoo_env’dependency method, you can access the current odoo environment. With this
environment, you can access the registry and therefore the model you want to
delegate the implementation to. If you want to change the implementation of
the route handler‘/demo/echo’, the only thing you have to do is to
inherit from the model where the implementation is defined and override the
method‘echo’.frompydanticimportBaseModelfromfastapiimportDepends,APIRouterfromodooimportmodelsfromodoo.addons.fastapi.dependenciesimportodoo_envclassFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"def_get_fastapi_routers(self)->List[APIRouter]:routers=super()._get_fastapi_routers()routers.append(demo_api_router)returnroutersdemo_api_router=APIRouter()@demo_api_router.get("/echo",response_model=EchoResponse,dependencies=[Depends(odoo_env)],)asyncdefecho(message:str,odoo_env:Annotated[Environment,Depends(odoo_env)],)->EchoResponse:"""Echo the message"""returnEchoResponse(message=odoo_env["demo.fastapi.endpoint"].echo(message))classEchoResponse(BaseModel):message:strclassDemoEndpoint(models.AbstractModel):_name="demo.fastapi.endpoint"_description="Demo Endpoint"defecho(self,message:str)->str:returnmessageclassDemoEndpointInherit(models.AbstractModel):_inherit="demo.fastapi.endpoint"defecho(self,message:str)->str:returnf"Hello{message}"NoteIt’s a good programming practice to implement the business logic outside
the route handler. This way, you can easily test your business logic without
having to test the route handler. In the example above, the business logic
is implemented in the method‘echo’of the model‘demo.fastapi.endpoint’.
The route handler just delegate the implementation to this method.Overriding the dependencies of the route handlerAs you’ve previously seen, the dependency injection mechanism of fastapi is
very powerful. By designing your route handler to rely on dependencies with
a specific functional scope, you can easily change the implementation of the
dependency without having to change the route handler. With such a design, you
can even define abstract dependencies that must be implemented by the concrete
application. This is the case of the‘authenticated_partner’dependency in our
previous example. (you can find the implementation of this dependency in the
file‘odoo/addons/fastapi/dependencies.py’and it’s usage in the file‘odoo/addons/fastapi/models/fastapi_endpoint_demo.py’)Adding a new route handlerLet’s say that you want to add a new route handler‘/demo/echo2’.
You could be tempted to add this new route handler in your new addons by
importing the router of the existing app and adding the new route handler to
it.fromodoo.addons.fastapi.models.fastapi_endpoint_demoimportdemo_api_router@demo_api_router.get("/echo2",response_model=EchoResponse,dependencies=[Depends(odoo_env)],)asyncdefecho2(message:str,odoo_env:Annotated[Environment,Depends(odoo_env)],)->EchoResponse:"""Echo the message"""echo=odoo_env["demo.fastapi.endpoint"].echo2(message)returnEchoResponse(message=f"Echo2:{echo}")The problem with this approach is that you unconditionally add the new route
handler to the existing app even if the app is called for a different database
where your new addon is not installed.The solution is to define a new router and to add it to the list of routers
returned by the method‘_get_fastapi_routers’of the model‘fastapi.endpoint’you are inheriting from into your new addon.classFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"def_get_fastapi_routers(self)->List[APIRouter]:routers=super()._get_fastapi_routers()ifself.app=="demo":routers.append(additional_demo_api_router)returnroutersadditional_demo_api_router=APIRouter()@additional_demo_api_router.get("/echo2",response_model=EchoResponse,dependencies=[Depends(odoo_env)],)asyncdefecho2(message:str,odoo_env:Annotated[Environment,Depends(odoo_env)],)->EchoResponse:"""Echo the message"""echo=odoo_env["demo.fastapi.endpoint"].echo2(message)returnEchoResponse(message=f"Echo2:{echo}")In this way, the new router is added to the list of routers of your app only if
the app is called for a database where your new addon is installed.Extending the model used as parameter or as response of the route handlerThe fastapi python library uses the pydantic library to define the models. By
default, once a model is defined, it’s not possible to extend it. However, a
companion python library calledextendable_pydanticprovides
a way to use inheritance with pydantic models to extend an existing model. If
used alone, it’s your responsibility to instruct this library the list of
extensions to apply to a model and the order to apply them. This is not very
convenient. Fortunately, an dedicated odoo addon exists to make this process
complete transparent. This addon is calledodoo-addon-extendable-fastapi.When you want to allow other addons to extend a pydantic model, you must
first define the model as an extendable model by using a dedicated metaclassfrompydanticimportBaseModelfromextendable_pydanticimportExtendableModelMetaclassPartner(BaseModel,metaclass=ExtendableModelMeta):name=0.1As any other pydantic model, you can now use this model as parameter or as response
of a route handler. You can also use all the features of models defined with
pydantic.@demo_api_router.get("/partner",response_model=Location,dependencies=[Depends(authenticated_partner)],)asyncdefpartner(partner:Annotated[ResPartner,Depends(authenticated_partner)],)->Partner:"""Return the location"""returnPartner.from_orm(partner)If you need to add a new field into the model‘Partner’, you can extend it
in your new addon by defining a new model that inherits from the model‘Partner’.fromtypingimportOptionalfromodoo.addons.fastapi.models.fastapi_endpoint_demoimportPartnerclassPartnerExtended(Partner,extends=Partner):email:Optional[str]If your new addon is installed in a database, a call to the route handler‘/demo/partner’will return a response with the new field‘email’if a
value is provided by the odoo record.{"name":"John Doe","email":"jhon.doe@acsone.eu"}If your new addon is not installed in a database, a call to the route handler‘/demo/partner’will only return the name of the partner.{"name":"John Doe"}NoteThe liskov substitution principle has also to be respected. That means that
if you extend a model, you must add new required fields or you must provide
default values for the new optional fields.Managing security into the route handlersBy default the route handlers are processed using the user configured on the‘fastapi.endpoint’model instance. (default is the Public user).
You have seen previously how to define a dependency that will be used to enforce
the authentication of a partner. When a method depends on this dependency, the
‘authenticated_partner_id’ key is added to the context of the partner environment.
(If you don’t need the partner as dependency but need to get an environment
with the authenticated user, you can use the dependency ‘authenticated_partner_env’ instead of
‘authenticated_partner’.)The fastapi addon extends the ‘ir.rule’ model to add into the evaluation context
of the security rules the key ‘authenticated_partner_id’ that contains the id
of the authenticated partner.As briefly introduced in a previous section, a good practice when you develop a
fastapi app and you want to protect your data in an efficient and traceable way is to:create a new user specific to the app but with any access rights.create a security group specific to the app and add the user to this group. (This
group must implies the group ‘AFastAPI Endpoint Runner’ that give the
minimal access rights)for each model you want to protect:add a ‘ir.model.access’ record for the model to allow read access to your model
and add the group to the record.create a new ‘ir.rule’ record for the model that restricts the access to the
records of the model to the authenticated partner by using the key
‘authenticated_partner_id’ in domain of the rule. (or to the user defined on
the ‘fastapi.endpoint’ model instance if the method is public)add a dependency on the ‘authenticated_partner’ to your handlers when you need
to access the authenticated partner or ensure that the service is called by an
authenticated partner.<recordid="my_demo_app_user"model="res.users"context="{'no_reset_password': True, 'no_reset_password': True}"><fieldname="name">MyDemoEndpointUser</field><fieldname="login">my_demo_app_user</field><fieldname="groups_id"eval="[(6, 0, [])]"/></record><recordid="my_demo_app_group"model="res.groups"><fieldname="name">MyDemoEndpointGroup</field><fieldname="users"eval="[(4, ref('my_demo_app_user'))]"/><fieldname="implied_ids"eval="[(4, ref('group_fastapi_endpoint_runner'))]"/></record><!-- acl for the model 'sale.order' --><recordid="sale_order_demo_app_access"model="ir.model.access"><fieldname="name">MyDemoApp:accesstosale.order</field><fieldname="model_id"ref="model_sale_order"/><fieldname="group_id"ref="my_demo_app_group"/><fieldname="perm_read"eval="True"/><fieldname="perm_write"eval="False"/><fieldname="perm_create"eval="False"/><fieldname="perm_unlink"eval="False"/></record><!-- a record rule to allows the authenticated partner to access only its sale orders --><recordid="demo_app_sale_order_rule"model="ir.rule"><fieldname="name">SaleOrderRule</field><fieldname="model_id"ref="model_sale_order"/><fieldname="domain_force">[('partner_id','=',authenticated_partner_id)]</field><fieldname="groups"eval="[(4, ref('my_demo_app_group'))]"/></record>How to test your fastapi appThanks to the starlette test client, it’s possible to test your fastapi app
in a very simple way. With the test client, you can call your route handlers
as if they were real http endpoints. The test client is available in the‘fastapi.testclient’module.Once again the dependency injection mechanism comes to the rescue by allowing
you to inject into the test client specific implementations of the dependencies
normally provided by the normal processing of the request by the fastapi app.
(for example, you can inject a mock of the dependency ‘authenticated_partner’
to test the behavior of your route handlers when the partner is not authenticated,
you can also inject a mock for the odoo_env etc…)The fastapi addon provides a base class for the test cases that you can use to
write your tests. This base class is‘odoo.fastapi.tests.common.FastAPITransactionCase’.
This class mainly provides the method‘_create_test_client’that you can
use to create a test client for your fastapi app. This method encapsulates the
creation of the test client and the injection of the dependencies. It also
ensures that the odoo environment is make available into the context of the
route handlers. This method is designed to be used when you need to test your
app or when you need to test a specific router (It’s therefore easy to defines
tests for routers in an addon that doesn’t provide a fastapi endpoint).With this base class, writing a test for a route handler is as simple as:fromodoo.fastapi.tests.commonimportFastAPITransactionCasefromodoo.addons.fastapiimportdependenciesfromodoo.addons.fastapi.routersimportdemo_routerclassFastAPIDemoCase(FastAPITransactionCase):@classmethoddefsetUpClass(cls)->None:super().setUpClass()cls.default_fastapi_running_user=cls.env.ref("fastapi.my_demo_app_user")cls.default_fastapi_authenticated_partner=cls.env["res.partner"].create({"name":"FastAPI Demo"})deftest_hello_world(self)->None:withself._create_test_client(router=demo_router)astest_client:response:Response=test_client.get("/demo/")self.assertEqual(response.status_code,status.HTTP_200_OK)self.assertDictEqual(response.json(),{"Hello":"World"})In the previous example, we created a test client for the demo_router. We could
have created a test client for the whole app by not specifying the router but
the app instead.fromodoo.fastapi.tests.commonimportFastAPITransactionCasefromodoo.addons.fastapiimportdependenciesfromodoo.addons.fastapi.routersimportdemo_routerclassFastAPIDemoCase(FastAPITransactionCase):@classmethoddefsetUpClass(cls)->None:super().setUpClass()cls.default_fastapi_running_user=cls.env.ref("fastapi.my_demo_app_user")cls.default_fastapi_authenticated_partner=cls.env["res.partner"].create({"name":"FastAPI Demo"})deftest_hello_world(self)->None:demo_endpoint=self.env.ref("fastapi.fastapi_endpoint_demo")withself._create_test_client(app=demo_endpoint._get_app())astest_client:response:Response=test_client.get(f"{demo_endpoint.root_path}/demo/")self.assertEqual(response.status_code,status.HTTP_200_OK)self.assertDictEqual(response.json(),{"Hello":"World"})NoteTo avoid trouble between the threads manipulation when the registry is
loading and the running of the tests, your tests must be run once the
registry is loaded. That’s why your test classes must be tagged with the tags
‘post_install’ and ‘-at_install’.Overall considerations when you develop an fastapi appDeveloping a fastapi app requires to follow some good practices to ensure that
the app is robust and easy to maintain. Here are some of them:A route handler must be as simple as possible. It must not contain any
business logic. The business logic must be implemented into the service
layer. The route handler must only call the service layer and return the
result of the service layer. To ease extension on your business logic, your
service layer can be implemented as an odoo abstract model that can be
inherited by other addons.A route handler should not expose the internal data structure and api of Odoo.
It should provide the api that is needed by the client. More widely, an app
provides a set of services that address a set of use cases specific to
a well defined functional domain. You must always keep in mind that your api
will remain the same for a long time even if you upgrade your odoo version
of modify your business logic.A route handler is a transactional unit of work. When you design your api
you must ensure that the completeness of a use case is guaranteed by a single
transaction. If you need to perform several transactions to complete a use
case, you introduce a risk of inconsistency in your data or extra complexity
in your client code.Properly handle the errors. The route handler must return a proper error
response when an error occurs. The error response must be consistent with
the rest of the api. The error response must be documented in the api
documentation. By default, the‘odoo-addon-fastapi’module handles
the common exception types defined in the‘odoo.exceptions’module
and returns a proper error response with the corresponding http status code.
An error in the route handler must always return an error response with a
http status code different from 200. The error response must contain a
human readable message that can be displayed to the user. The error response
can also contain a machine readable code that can be used by the client to
handle the error in a specific way.When you design your json document through the pydantic models, you must
use the appropriate data types. For example, you must use the data type‘datetime.date’to represent a date and not a string. You must also
properly define the constraints on the fields. For example, if a field
is optional, you must use the data type‘typing.Optional’.pydanticprovides everything you need to
properly define your json document.Always use an appropriate pydantic model as request and/or response for
your route handler. Constraints on the fields of the pydantic model must
apply to the specific use case. For example, if your route handler is used
to create a sale order, the pydantic model must not contain the field
‘id’ because the id of the sale order will be generated by the route handler.
But if the id is required afterwords, the pydantic model for the response
must contain the field ‘id’ as required.Uses descriptive property names in your json documents. For example, avoid the
use of documents providing a flat list of key value pairs.Be consistent in the naming of your fields into your json documents. For example,
if you use ‘id’ to represent the id of a sale order, you must use ‘id’ to represent
the id of all the other objects.Be consistent in the naming style of your fields. Always prefer underscore
to camel case.Always use plural for the name of the fields that contain a list of items.
For example, if you have a field ‘lines’ that contains a list of sale order
lines, you must use ‘lines’ and not ‘line’.You can’t expect that a client will provide you the identifier of a specific
record in odoo (for example the id of a carrier) if you don’t provide a
specific route handler to retrieve the list of available records. Sometimes,
the client must share with odoo the identity of a specific record to be
able to perform an appropriate action specific to this record (for example,
the processing of a payment is different for each payment acquirer). In this
case, you must provide a specific attribute that allows both the client and
odoo to identify the record. The field ‘provider’ on a payment acquirer allows
you to identify a specific record in odoo. This kind of approach
allows both the client and odoo to identify the record without having to rely
on the id of the record. (This will ensure that the client will not break
if the id of the record is changed in odoo for example when tests are run
on an other database).Always use the same name for the same kind of object. For example, if you
have a field ‘lines’ that contains a list of sale order lines, you must
use the same name for the same kind of object in all the other json documents.Manage relations between objects in your json documents the same way.
By default, you should return the id of the related object in the json document.
But this is not always possible or convenient, so you can also return the
related object in the json document. The main advantage of returning the id
of the related object is that it allows you to avoid then+1 problem. The
main advantage of returning the related object in the json document is that
it allows you to avoid an extra call to retrieve the related object.
By keeping in mind the pros and cons of each approach, you can choose the
best one for your use case. Once it’s done, you must be consistent in the
way you manage the relations of the same object.It’s not always a good idea to name your fields into your json documents
with the same name as the fields of the corresponding odoo model. For example,
in your document representing a sale order, you must not use the name ‘order_line’
for the field that contains the list of sale order lines. The name ‘order_line’
in addition to being confusing and not consistent with the best practices, is
not auto-descriptive. The name ‘lines’ is much better.Keep a defensive programming approach. If you provide a route handler that
returns a list of records, you must ensure that the computation of the list
is not too long or will not drain your server resources. For example,
for search route handlers, you must ensure that the search is limited to
a reasonable number of records by default.As a corollary of the previous point, a search handler must always use the
pagination mechanism with a reasonable default page size. The result list
must be enclosed in a json document that contains the total number of records
and the list of records.Use plural for the name of a service. For example, if you provide a service
that allows you to manage the sale orders, you must use the name ‘sale_orders’
and not ‘sale_order’.… and many more.We could write a book about the best practices to follow when you design your api
but we will stop here. This list is the result of our experience atACSONE SA/NVand it evolves over time. It’s a kind of rescue kit that we
would provide to a new developer that starts to design an api. This kit must
be accompanied with the reading of some useful resources link like theREST Guidelines. On a technical level,
thefastapi  documentationprovides a lot of
useful information as well, with a lot of examples. Last but not least, thepydanticdocumentation is also very useful.MiscellaneousDevelopment of a search route handlerThe‘odoo-addon-fastapi’module provides 2 useful piece of code to help
you be consistent when writing a route handler for a search route.A dependency method to use to specify the pagination parameters in the same
way for all the search route handlers:‘odoo.addons.fastapi.paging’.A PagedCollection pydantic model to use to return the result of a search route
handler enclosed in a json document that contains the total number of records.importsysifsys.version_info>=(3,9):fromtypingimportAnnotatedelse:fromtyping_extensionsimportAnnotatedfrompydanticimportBaseModelfromodoo.apiimportEnvironmentfromodoo.addons.fastapi.dependenciesimportpaging,authenticated_partner_envfromodoo.addons.fastapi.schemasimportPagedCollection,PagingclassSaleOrder(BaseModel):id:intname:str@router.get("/sale_orders",response_model=PagedCollection[SaleOrder],response_model_exclude_unset=True,)defget_sale_orders(paging:Annotated[Paging,Depends(paging)],env:Annotated[Environment,Depends(authenticated_partner_env)],)->PagedCollection[SaleOrder]:"""Get the list of sale orders."""count=env["sale.order"].search_count([])orders=env["sale.order"].search([],limit=paging.limit,offset=paging.offset)returnPagedCollection[SaleOrder](total=count,items=[SaleOrder.from_orm(order)fororderinorders],)NoteThe‘odoo.addons.fastapi.schemas.Paging’and‘odoo.addons.fastapi.schemas.PagedCollection’pydantic models are not designed to be extended to not introduce a
dependency between the‘odoo-addon-fastapi’module and the‘odoo-addon-extendable’Customization of the error handlingThe error handling a very important topic in the design of the fastapi integration
with odoo. It must ensure that the error messages are properly return to the client
and that the transaction is properly roll backed. The‘fastapi’module provides
a way to register custom error handlers. The‘odoo.addons.fastapi.error_handlers’module provides the default error handlers that are registered by default when
a new instance of the‘FastAPI’class is created. When an app is initialized in
‘fastapi.endpoint’ model, the method_get_app_exception_handlersis called to
get a dictionary of error handlers. This method is designed to be overridden
in a custom module to provide custom error handlers. You can override the handler
for a specific exception class or you can add a new handler for a new exception
or even replace all the handlers by your own handlers. Whatever you do, you must
ensure that the transaction is properly roll backed.Some could argue that the error handling can’t be extended since the error handlers
are global method not defined in an odoo model. Since the method providing the
the error handlers definitions is defined on the ‘fastapi.endpoint’ model, it’s
not a problem at all, you just need to think another way to do it that by inheritance.A solution could be to develop you own error handler to be able to process the
error and chain the call to the default error handler.classMyCustomErrorHandler():def__init__(self,next_handler):self.next_handler=next_handlerdef__call__(self,request:Request,exc:Exception)->JSONResponse:# do something with the errorresponse=self.next_handler(request,exc)# do something with the responsereturnresponseWith this solution, you can now register your custom error handler by overriding
the method_get_app_exception_handlersin your custom module.classFastapiEndpoint(models.Model):_inherit="fastapi.endpoint"def_get_app_exception_handlers(self,)->Dict[Union[int,Type[Exception]],Callable[[Request,Exception],Union[Response,Awaitable[Response]]],]:handlers=super()._get_app_exception_handlers()access_error_handler=handlers.get(odoo.exceptions.AccessError)handlers[odoo.exceptions.AccessError]=MyCustomErrorHandler(access_error_handler)returnhandlersIn the previous example, we extend the error handler for the ‘AccessError’ exception
for all the endpoints. You can do the same for a specific app by checking the
‘app’ field of the ‘fastapi.endpoint’ record before registering your custom error
handler.FastAPI addons directory structureWhen you develop a new addon to expose an api with fastapi, it’s a good practice
to follow the same directory structure and naming convention for the files
related to the api. It will help you to easily find the files related to the api
and it will help the other developers to understand your code.Here is the directory structure that we recommend. It’s based on practices that
are used in the python community when developing a fastapi app..
├── x_api
│   ├── data
│   │   ├── ... .xml
│   ├── demo
│   │   ├── ... .xml
│   ├── i18n
│   │   ├── ... .po
│   ├── models
│   │   ├── __init__.py
│   │   ├── fastapi_endpoint.py  # your app
│   │   └── ... .py
│   └── routers
│   │   ├── __init__.py
│   │   ├── items.py
│   │   └── ... .py
│   ├── schemas | schemas.py
│   │   ├── __init__.py
│   │   ├── my_model.py  # pydantic model
│   │   └── ... .py
│   ├── security
│   │   ├── ... .xml
│   ├── views
│   │   ├── ... .xml
│   ├── __init__.py
│   ├── __manifest__.py
│   ├── dependencies.py  # custom dependencies
│   ├── error_handlers.py  # custom error handlersThe‘models’directory contains the odoo models. When you define a new
app, as for the others addons, you will add your new model inheriting from
the‘fastapi.endpoint’model in this directory.The‘routers’directory contains the fastapi routers. You will add your
new routers in this directory. Each route starting with the same prefix should
be grouped in the same file. For example, all the routes starting with
‘/items’ should be defined in the‘items.py’file. The‘__init__.py’file in this directory is used to import all the routers defined in the
directory and create a global router that can be used in an app. For example,
in your‘items.py’file, you will define a router like this:router=APIRouter(tags=["items"])router.get("/items",response_model=List[Item])deflist_items():passIn the‘__init__.py’file, you will import the router and add it to the global
router or your addon.fromfastapiimportAPIRouterfrom.itemsimportrouterasitems_routerrouter=APIRouter()router.include_router(items_router)The‘schemas.py’will be used to define the pydantic models. For complex
APIs with a lot of models, it will be better to create a‘schemas’directory
and split the models in different files.  The‘__init__.py’file in this
directory will be used to import all the models defined in the directory.
For example, in your‘my_model.py’file, you will define a model like this:frompydanticimportBaseModelclassMyModel(BaseModel):name:strdescription:str=NoneIn the‘__init__.py’file, you will import the model’s classes from the
files in the directory.from.my_modelimportMyModelThis will allow to always import the models from the schemas module whatever
the models are spread across different files or defined in the‘schemas.py’file.fromx_api_addon.schemasimportMyModelThe‘dependencies.py’file contains the custom dependencies that you
will use in your routers. For example, you can define a dependency to
check the access rights of the user.The‘error_handlers.py’file contains the custom error handlers that you
will use in your routers. The‘odoo-addon-fastapi’module provides the
default error handlers for the common odoo exceptions. Chance are that you
will not need to define your own error handlers. But if you need to do it,
you can define them in this file.What’s next?The‘odoo-addon-fastapi’module is still in its early stage of development.
It will evolve over time to integrate your feedback and to provide the missing
features. It’s now up to you to try it and to provide your feedback.Known issues / RoadmapTheroadmapandknown issuescan
be found on GitHub.TheFastAPImodule provides an easy way to use WebSockets. Unfortunately, this
support is not ‘yet’ available in theOdooframework. The challenge is high
because the integration of the fastapi is based on the use of a specific middleware
that convert the WSGI request consumed by odoo to a ASGI request. The question
is to know if it is also possible to develop the same kind of bridge for the
WebSockets and to stream large responses.Bug TrackerBugs are tracked onGitHub Issues.
In case of trouble, please check there if your issue has already been reported.
If you spotted it first, help us smashing it by providing a detailed and welcomedfeedback.Do not contact contributors directly about support or help with technical issues.CreditsAuthorsACSONE SA/NVContributorsLaurent Mignon <laurent.mignon@acsone.eu>MaintainersThis module is maintained by the OCA.OCA, or the Odoo Community Association, is a nonprofit organization whose
mission is to support the collaborative development of Odoo features and
promote its widespread use.Currentmaintainer:This module is part of theOCA/rest-frameworkproject on GitHub.You are welcome to contribute. To learn how please visithttps://odoo-community.org/page/Contribute.