panamap 1.2.3
Python object mapper
License: MIT
Keywords: object mapper

# panamap

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Panamap is a Python object mapper. It is useful to avoid boilerplate code when copying data between objects with
similar data, for example protobuf generated files and domain models.

## Installation

Use the package manager [pip](https://pip.pypa.io/en/stable/) to install panamap.

```bash
pip install panamap
```

## Usage

### Mapping primitive values

The most simple usage of panamap is to map primitive values:

```python
from panamap import Mapper

mapper = Mapper()
print(mapper.map("123", int) + 1)
# 124
```

There is a set of standart primitive values converters.

### Mapping classes with converter

The most straitforward usage of mapper is to set converter from class A to class B. 
Here is an example of such setup:

```python
from panamap import Mapper

class A:
    def __init__(self, a_value: int):
        self.a_value = a_value


class B:
    def __init__(self, b_value: int):
        self.b_value = b_value

mapper = Mapper()
mapper.mapping(A, B) \
    .l_to_r_converter(lambda a: B(a.a_value)) \
    .register()

b = mapper.map(A(123), B)
print(b.b_value)
# 123
```

If there is limited set of values, enums are most common case, you can use utility function `values_map`:

```python
from enum import Enum
from panamap import Mapper, values_map

class LangA(Enum):
    PYTHON = 1
    JAVA = 2
    CPP = 3


class LangB(Enum):
    PY = 1
    JAVA = 2
    CPP = 3


mapper = Mapper()
mapper.mapping(LangA, LangB) \
    .l_to_r_converter(values_map({
        LangA.PYTHON: LangB.PY,
        LangA.JAVA: LangB.JAVA,
        LangA.CPP: LangB.CPP,
    })) \
    .register()

print(mapper.map(LangA.PYTHON, LangB).name)
# PY
```

### Mapping context

In some cases you need to pass some context to mapping operation. 
You can do it with `context` parameter in `map` method.
Context is a dict and will be passed to converter as a second argument.

```python
from panamap import Mapper


class A:
    def __init__(self, a_value: int):
        self.a_value = a_value


class B:
    def __init__(self, b_value: int, contextual: str):
        self.b_value = b_value
        self.contextual = contextual


mapper = Mapper()
mapper.mapping(A, B) \
    .l_to_r_converter(lambda a, ctx: B(a.a_value, ctx["contextual"])) \
    .register()

b = mapper.map(A(123), B, {"contextual": "contextual value"})
print(b.contextual)
# 'contextual value'
```

### Mapping simple classes

To set up mapping call `mapping` function of mapper object.
Each field pair can be bind with `bidirectional` function or separately with `l_to_r` and `r_to_l` if we only need one
directional mapping or there is custom conversion on mapping.

Here are some examples:

```python
from panamap import Mapper

class A:
    def __init__(self, a_value: int):
        self.a_value = a_value


class B:
    def __init__(self, b_value: int):
        self.b_value = b_value

mapper = Mapper()
mapper.mapping(A, B) \
    .l_to_r("a_value", "b_value") \
    .register()

b = mapper.map(A(123), B)
print(b.b_value)
# 123
# a = mapper.map(B(123), A) will raise MissingMappingException cause we didn't set any r_to_l map rules

bidirectional_mapper = Mapper()
bidirectional_mapper.mapping(A, B) \
    .bidirectional("a_value", "b_value") \
    .register()

b = bidirectional_mapper.map(A(123), B)
print(b.b_value)
# 123
a = bidirectional_mapper.map(B(123), A)
print(a.a_value)
# 123

shifting_mapper = Mapper()
shifting_mapper.mapping(A, B) \
    .l_to_r("a_value", "b_value", lambda a: a + 1) \
    .r_to_l("a_value", "b_value", lambda b: b - 1) \
    .register()

b = shifting_mapper.map(A(123), B)
print(b.b_value)
# 124
a = shifting_mapper.map(B(123), A)
print(a.a_value)
# 122
```

### Mapping empty classes

Sometimes there is need to convert one empty class to another. For such case there is `_empty` versions of map config
functions:

```python
from panamap import Mapper

class A:
    pass

class B:
    pass

mapper = Mapper()
mapper.mapping(A, B) \
    .bidirectional_empty() \
    .register()

b = mapper.map(A(), B)
print(isinstance(b, B))
# True
```

### Mapping nested fields

Panamap supports mapping of nested fields. To perform this mapping for nested fields classes must be set up.

```python
from dataclasses import dataclass
from panamap import Mapper

@dataclass
class NestedA:
    value: str


@dataclass
class A:
    value: NestedA


@dataclass
class NestedB:
    value: str


@dataclass
class B:
    value: NestedB

mapper = Mapper()
mapper.mapping(A, B) \
    .map_matching() \
    .register()
mapper.mapping(NestedA, NestedB) \
    .map_matching() \
    .register()

b = mapper.map(A(NestedA("abc")), B)
print(isinstance(b.value, NestedB))
# True
print(b.value.value)
# abc
```

### Mapping from and to dict

Panamap allow to set up mapping frm and to dict object. Here is an example:

```python
from typing import List
from dataclasses import dataclass
from panamap import Mapper

@dataclass
class Nested:
    value: str


@dataclass
class A:
    nested: Nested
    list_of_nested: List[Nested]

mapper = Mapper()
mapper.mapping(A, dict) \
    .map_matching() \
    .register()
mapper.mapping(Nested, dict) \
    .map_matching() \
    .register()

a = mapper.map(
    {
        "nested": {
            "value": "abc",
        },
        "list_of_nested": [
            {"value": "def",},
            {"value": "xyz",},
        ]
    },
    A,
)
print(a)
# A(nested=Nested(value='abc'), list_of_nested=[Nested(value='def'), Nested(value='xyz')])
```

### Mapping protobuf generated classes

To map protobuf generated classes use separate module [panamap-proto](https://github.com/panamap-object-mapper/panamap-proto).

## Contributing

Contributing described in [separate document](docs/contributing.md).