DynamicNestedField 0.0.16
DynamicNestedField is a set of tools used to perform dynamic nested operation on django models.
Requires Python: >=3.9

# DynamicNestedField

`DynamicNestedField` is a set of tools used to perform dynamic nested operation on django models without worrying about the problems and authentication leaks that come with it.

This library has support for `django-restql` and `django-filter` with predefined filters for main django model fields.

## Installation

Install using `pip`...

```
$ pip install DynamicNestedField
```

## Usage & Example

Working with this library is semilunar to using normal serializers, we will create simple project that contains several models with m2m and foreignkey relations...

***👉 You can find a simple example project [on GitHub](https://github.com/NAMEER242/DynamicNestedField_Showcase).***

* model: `A`
  * ManyToMany: model: `B`
    * ForeignKey: model: `C`

### models:

Here we will define three models as following...

```py
from django.db import models


class C(models.Model):
    charfield = models.CharField(max_length=100)


class B(models.Model):
    charfield = models.CharField(max_length=100)
    c = models.ForeignKey(C, on_delete=models.CASCADE, null=True, blank=True)


class A(models.Model):
    charfield = models.CharField(max_length=100)
    b = models.ManyToManyField(B)

```

### Serializers:

And this is the main serializers that we are using to perform all models operations, we will talk about it just in seconds.

```py
class C_Serializer(DynamicNestedMixin):
    class Meta:
        model = C
        fields = ['charfield']
        permission_classes = [IsAuthenticated]  # the general permission class.
        permission_classes_by_method = {
            'GET': [IsAuthenticated],
            'POST': [IsAuthenticated],
            'PUT': [IsAuthenticated],
            'DELETE': [IsAuthenticated],
            # and so on.
        }


class B_Serializer(DynamicNestedMixin):
    c = C_Serializer()

    class Meta:
        model = B
        fields = ['charfield', 'c']
        DNM_config = {  # DNM_config holds all the configuration needed.
            "c": {
                "filter": "id",
            }
        }
        permission_classes = [IsAuthenticated]  # the general permission class.
        permission_classes_by_method = {
            'GET': [IsAuthenticated],
            'POST': [IsAuthenticated],
            'PUT': [IsAuthenticated],
            'DELETE': [IsAuthenticated],
            # and so on.
        }


class A_Serializer(DynamicNestedMixin):
    b = B_Serializer(many=True)  # many=True for m2m.

    class Meta:
        model = A
        fields = ['charfield', 'b']
        DNM_config = {  # DNM_config holds all the configuration needed.
            "b": {
                "filter": "id",
            }
        }
        permission_classes = [IsAuthenticated]  # the general permission class.
        permission_classes_by_method = {
            'GET': [IsAuthenticated],
            'POST': [IsAuthenticated],
            'PUT': [IsAuthenticated],
            'DELETE': [IsAuthenticated],
            # and so on.
        }

```

As you can see we define our serializers as usual, except this time we use three new variables in our Meta class, the first one is `permission_classes` this variable is an instance of djangoRestFramework VewSet class permission_classes variable it does the same thing, takes a list of `BasePermission` classes that can be used to define permissions by using predefined permissions classes or by creating your own.

The second Variable is `permission_classes_by_method` this is the same as the previous `permission_classes` but here we can define a dict var with its keys as request methods (POST, PUT, GET ...) so we can set custom permissions for each one, if you didn't specify a request method here then the library will use the default permissions that are located in `permission_classes`.

Last variable and the most important one is `DNM_config`, here we define all serializer fields configuration
The default options we have in `DNM_config` are as following...

```py
DNM_config = {
            "field": {  # Default Values...
                "create_new_instance": True,  # if you want to perform create operation on this field.
                "can_be_edited": True,  # if you want to perform update operation on this field.
                "clear_data": False,  # if you want to clear field data before updating it (like if it was m2m relation, and you want to clear the data every time you update using this serializer).
                "filter": [None],  # the filter field used to get old data of this field from the database, if the first filter was not found then it will check for the secondary if exists (this attribute must be defined). 
                "serializer": None  # you can set a serializer for this field the library will search for it by itself.
            }
        }
```

In this configuration dict the only required attribute is filter, it is a list of str names for serializer fields that we will use to find old model data, you can use up to 2 filters inside the filter attr the first every one of them has some special logics...
let `filter=['id', 'name']`
* in the first filter `id` we will search for an item with `id=filter['id']` if we found one we use it else we raise an exception.
* but in the second filter `name` we will search for an item with `name=filter['name']` if we found one we use it else we create a new item with `name=filter['name']`.
* if there was a third filter then we wil skip it in this library version.

Here the filter attribute is the only required attribute the rest of them can be removed, and the library will set its default values.

### views:

Last step is defining out ViewSets...

```py
class C_ViewSet(NestedModelViewSet):
    queryset = C.objects.all()
    serializer_class = C_Serializer


class B_ViewSet(NestedModelViewSet):
    queryset = B.objects.all()
    serializer_class = B_Serializer


class A_ViewSet(NestedModelViewSet):
    queryset = A.objects.all()
    serializer_class = A_Serializer

```

As you can see our ViewSets are so brief and simple thanks to the abbreviation of all the operation of the nested models.

### Using The Api

Now we can run the project and try our new api...

#### POST:

```
{
  "charfield": "a",
  "b": [
    {
      "charfield": "b",
      "c": {
        "charfield": "c"
      }
    }
  ]
}
```

This will create model A first and then will start creating model B data and inserting it to field A, and the same thing with model C data.

#### POST: with using old data...

```
{
  "charfield": "a",
  "b": [
    {
      "id": 1
    }
  ]
}
```

or

```
{
  "charfield": "a",
  "b": [1]
}
```

Here we use an old B model data with id=1.

#### PUT & PATCH:

```
{
  "id": 1,
  "charfield": "a_updated_name",
  "b": [
    {
      "charfield": "b",
      "c": {
        "charfield": "c"
      }
    }
  ]
}
```

This will get model A data with id=1 and update it's a var to `a_updated_name` and create new model B data and set it to out A model that we get first.

#### PUT & PATCH: with old data...

```
{
  "id": 1,
  "charfield": "a_updated_name",
  "b": [2]
}
```

Here it will get model A data with id=1 and add new b var data with id=2.

In short, you can...

* you can create nested models that are inside other models.
* you can update models by setting filter attr value (e.g. `id=1`, or `username="nameer"`).
* you can set old models data by using just the filter attr value without specifying attr name (e.g. `m2m_relation_field=[1,2,3]` or `foreignkey_field="nameer"`)

and you can't:

* you can't update old models in create operation.

and that's it for today 😁

MIT License

Copyright (c) 2022 Nameer Haider

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