More encoders (#302)

* Update black
* Update mypy
* Add documentation about the encoders

.pre-commit-config.yaml

@@ -24,6 +24,14 @@ repos:
     hooks:
       - id: ruff
         args: ["--fix", "--line-length=99"]
+<<<<<<< HEAD
+=======
+  - repo: https://github.com/psf/black
+    rev: 24.4.1
+    hooks:
+      - id: black
+        args: ["--line-length=99"]
+>>>>>>> 932521b (More encoders (#302))
 ci:
   autofix_commit_msg: 🎨 [pre-commit.ci] Auto format from pre-commit.com hooks
   autoupdate_commit_msg: ⬆ [pre-commit.ci] pre-commit autoupdate

docs/encoders.md

@@ -0,0 +1,171 @@
+# Encoders
+
+Esmerald being built on top of Lilya, brings another level of flexibility, the **encoders**.
+
+Pretty much like Lilya, an Encoder is what allows a specific type of object to be understood,
+encoded and serialized by Esmerald without breaking the application.
+
+An example of default existing encoders in Esmerald would be the support for **Pydantic** and **MsgSpec**.
+
+!!! Warning
+    The encoders came to Esmerald after the version **3.1.2**. If you are using a version prior
+    to that, this won't be available.
+
+## Benefits of encoders
+
+The greatest benefit of supporting the encoders is that you don't need to rely on a specific framework
+to support a specific library for you to use.
+
+With Esmerald `Encoder` you can design it yourself and simply add it to Esmerald to be used making it
+**future proof** and extremely dynamic.
+
+## How to use it
+
+To take advantage of the Encoders **you must subclass the Encoder from Esmerald and implement three mandatory functions**.
+
+```python
+from esmerald.encoders import Encoder
+```
+
+When subclassing the `Encoder`, the mandatory functions are:
+
+* [`is_type()`](#is_type)
+* [`serialize()`](#serialize)
+* [`encode()`](#encode)
+
+Esmerald extends the native functionality of Lilya regarding the encoders and adds some extra flavours to it.
+
+The reasoning behind it its because Esmerald internally manages signatures and data validations that are
+unique to Esmerald.
+
+### is_type
+
+This function might sound confusing but it is in fact something simple. This function is used to check
+if the object of type X is an instance or a subclass of that same type.
+
+!!! Danger
+    Here is where it is different from Lilya. With Lilya you can use the `__type__` as well but
+    **not in Esmerald. In Esmerald you must implement the `is_type` function.
+
+#### Example
+
+This is what currently Esmerald is doing for Pydantic and MsgSpec.
+
+```python
+{!> ../docs_src/encoders/is_type.py !}
+```
+
+As you can see, this is how we check and verify if an object of type `BaseModel` and `Struct` are
+properly validated by Esmerald.
+
+### serialize
+
+This function is what tells Esmerald how to serialize the given object type into a JSON readable
+format.
+
+Quite simple and intuitive.
+
+#### Example
+
+```python
+{!> ../docs_src/encoders/serialize.py !}
+```
+
+### encode
+
+Finally, this functionality is what converts a given piece of data (JSON usually) into an object
+of the type of the Encoder.
+
+For example, a dictionary into Pydantic models or MsgSpec Structs.
+
+#### Example
+
+```python
+{!> ../docs_src/encoders/encode.py !}
+```
+
+### The flexibility
+
+As you can see, there are many ways of you building your encoders. Esmerald internally already brings
+two of them out of the box but you are free to build your own [custom encoder](#custom-encoders) and
+apply your own logic and validations.
+
+You have 100% the power and control over any validator you would love to have in your Esmerald application.
+
+### Custom Encoders
+
+Well, this is where it becomes interesting. What if you actually want to build an Encoder that is not
+currently supported by Esmerald natively, for example, the library `attrs`?
+
+It is in fact very simple as well, following the previous steps and explanations, it would look
+like this:
+
+```python
+{!> ../docs_src/encoders/custom.py !}
+```
+
+Do you see any differences compared to `Pydantic` and `MsgSpec`?
+
+Well, the `is_type` does not check for an `isinstance` or `is_class_and_subclass` and the reason
+for that its because when using `attrs` there is not specific object of type X like we have in others,
+in fact, the `attrs` uses decorators for it and by default provides a `has()` function that is used
+to check the `attrs` object types, so we can simply use it.
+
+Every library has its own ways, object types and everything in between to check and
+**this is the reason why the `is_type` exists, to make sure you have the control over the way the typing is checked**.
+
+Now imagine what you can do with any other library at your choice.
+
+### Register the Encoder
+
+Well, building the encoders is good fun but it does nothing to Esmerald unless you make it aware those
+in fact exist and should be used.
+
+There are different ways of registering the encoders.
+
+* Via [settings](#via-settings)
+* Via [instance](#via-instance)
+
+Esmerald also provides a function to register anywhere in your application but **it is not recommended**
+to use it without understanding the ramifications, mostly if you have handlers relying on a given
+object type that needs the encoder to be available before assembling the routing system.
+
+```python
+from esmerald.encoders import register_esmerald_encoder
+```
+
+#### Via Settings
+
+Like everything in Esmerald, you can use the settings for basically everything in your application.
+
+Let us use the example of the [custom encoder](#custom-encoders) `AttrsEncoder`.
+
+```python
+{!> ../docs_src/encoders/via_settings.py !}
+```
+
+#### Via Instance
+
+Classic approach and also available in any Esmerald or ChildEsmerald instance.
+
+```python
+{!> ../docs_src/encoders/via_instance.py !}
+```
+
+#### Adding an encoder via app instance function
+
+This is also available in any Esmerald and ChildEsmerald application. If you would like to add
+an encoder after instantiation you can do it but again, **it is not recommended**
+to use it without understanding the ramifications, mostly if you have handlers relying on a given
+object type that needs the encoder to be available before assembling the routing system.
+
+```python
+{!> ../docs_src/encoders/via_func.py !}
+```
+
+### Notes
+
+Having this level of flexibility is great in any application and Esmerald makes it easy for you but
+it is also important to understand that this level of control also comes with risks, meaning, when
+you build an encoder, make sure you test all the cases possible and more importantly, you implement
+**all the functions** mentioned above or else your application will break.

docs_src/encoders/custom.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from typing import Any
+
+from attrs import asdict, define, field, has
+
+from esmerald.encoders import Encoder
+
+
+class AttrsEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return has(value)
+
+    def serialize(self, obj: Any) -> Any:
+        return asdict(obj)
+
+    def encode(self, annotation: Any, value: Any) -> Any:
+        return annotation(**value)
+
+
+# The way an `attr` object is defined
+@define
+class AttrItem:
+    name: str = field()
+    age: int = field()
+    email: str

docs_src/encoders/encode.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+from typing import Any
+
+import msgspec
+from msgspec import Struct
+from pydantic import BaseModel
+
+from esmerald.encoders import Encoder
+from lilya._utils import is_class_and_subclass
+
+
+class MsgSpecEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, Struct) or is_class_and_subclass(value, Struct)
+
+    def serialize(self, obj: Any) -> Any:
+        return msgspec.json.decode(msgspec.json.encode(obj))
+
+    def encode(self, annotation: Any, value: Any) -> Any:
+        return msgspec.json.decode(msgspec.json.encode(value), type=annotation)
+
+
+class PydanticEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, BaseModel) or is_class_and_subclass(value, BaseModel)
+
+    def serialize(self, obj: BaseModel) -> dict[str, Any]:
+        return obj.model_dump()
+
+    def encode(self, annotation: Any, value: Any) -> Any:
+        if isinstance(value, BaseModel):
+            return value
+        return annotation(**value)

docs_src/encoders/is_type.py

@@ -0,0 +1,21 @@
+from __future__ import annotations
+
+from typing import Any
+
+from msgspec import Struct
+from pydantic import BaseModel
+
+from esmerald.encoders import Encoder
+from lilya._utils import is_class_and_subclass
+
+
+class MsgSpecEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, Struct) or is_class_and_subclass(value, Struct)
+
+
+class PydanticEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, BaseModel) or is_class_and_subclass(value, BaseModel)

docs_src/encoders/serialize.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+from typing import Any
+
+import msgspec
+from msgspec import Struct
+from pydantic import BaseModel
+
+from esmerald.encoders import Encoder
+from lilya._utils import is_class_and_subclass
+
+
+class MsgSpecEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, Struct) or is_class_and_subclass(value, Struct)
+
+    def serialize(self, obj: Any) -> Any:
+        return msgspec.json.decode(msgspec.json.encode(obj))
+
+
+class PydanticEncoder(Encoder):
+
+    def is_type(self, value: Any) -> bool:
+        return isinstance(value, BaseModel) or is_class_and_subclass(value, BaseModel)
+
+    def serialize(self, obj: BaseModel) -> dict[str, Any]:
+        return obj.model_dump()

docs_src/encoders/via_func.py

@@ -0,0 +1,8 @@
+from myapp.encoders import AttrsEncoder
+
+from esmerald import Esmerald
+
+app = Esmerald(
+    routes=[...],
+)
+app.register_encoder(AttrsEncoder)

docs_src/encoders/via_instance.py

@@ -0,0 +1,8 @@
+from myapp.encoders import AttrsEncoder
+
+from esmerald import Esmerald
+
+app = Esmerald(
+    routes=[...],
+    encoders=[AttrsEncoder],
+)

docs_src/encoders/via_settings.py

@@ -0,0 +1,12 @@
+from typing import List, Union
+
+from myapp.encoders import AttrsEncoder
+
+from esmerald import EsmeraldAPISettings
+from esmerald.encoders import Encoder
+
+
+class AppSettings(EsmeraldAPISettings):
+    @property
+    def encoders(self) -> Union[List[Encoder], None]:
+        return [AttrsEncoder]

mkdocs.yml

@@ -106,6 +106,7 @@ nav:
       - Request: "requests.md"
       - Context: "context.md"
       - Responses: "responses.md"
+      - Encoders: "encoders.md"
       - MsgSpec: "msgspec.md"
       - Background Tasks: "background-tasks.md"
       - Lifespan Events: "lifespan-events.md"