Provide additional context to marshall.

docs/marshalls.md

@@ -172,6 +172,36 @@ the remaining object, functions, attributes and operations, are.
 {!> ../docs_src/marshalls/method_field.py !}
 ```
 
+## Including additional context
+
+In certain scenarios, it is necessary to provide additional context to the marshall. Additional context can be provided by passing a context argument when instantiating the marshall.
+
+**Example**
+
+```python
+class UserMarshall(Marshall):
+    marshall_config: ConfigMarshall = ConfigMarshall(model=User, fields=["name", "email"],)
+    additional_context: fields.MarshallMethodField = fields.MarshallMethodField(field_type=dict[str, Any])
+
+    def get_additional_context(self, instance: edgy.Model) -> dict[str, Any]:
+        return self.context
+
+
+data = {"name": "Edgy", "email": "[email protected]"}
+marshall = UserMarshall(**data, context={"foo": "bar"})
+marshall.model_dump()
+```
+
+And the result will be:
+
+```json
+{
+    "name": "Edgy",
+    "email": "[email protected]",
+    "additional_context": {"foo": "bar"}
+}
+```
+
 ## `save()`
 
 Since the [Marshall](#marshall) is also a Pydantic base model, the same as Edgy, there may be some

edgy/core/marshalls/base.py

@@ -24,8 +24,10 @@ class BaseMarshall(BaseModel, metaclass=MarshallMeta):
     __show_pk__: ClassVar[bool] = False
     __custom_fields__: ClassVar[dict[str, BaseMarshallField]] = {}
 
-    def __init__(self, /, **data: Any) -> None:
-        super().__init__(**data)
+    def __init__(self, /, **kwargs: Any) -> None:
+        _context = kwargs.pop("context", {})
+        super().__init__(**kwargs)
+        self._context = _context
         self._instance: Model = self._setup()
 
     def _setup(self) -> "Model":
@@ -54,6 +56,10 @@ def instance(self) -> "Model":
     def instance(self, value: "Model") -> None:
         self._instance = value
 
+    @property
+    def context(self) -> dict:
+        return getattr(self, "_context", {})
+
     def _resolve_serializer(self, instance: "Model") -> "BaseMarshall":
         """
         Resolve serializer fields and populate them with data from the provided instance.

tests/marshalls/test_marshall_context.py

@@ -0,0 +1,109 @@
+from typing import Any
+
+import pytest
+
+import edgy
+from edgy.core.marshalls import Marshall, fields
+from edgy.core.marshalls.config import ConfigMarshall
+from edgy.testclient import DatabaseTestClient
+from tests.settings import DATABASE_URL
+
+database = DatabaseTestClient(DATABASE_URL)
+models = edgy.Registry(database=edgy.Database(database, force_rollback=True))
+
+pytestmark = pytest.mark.anyio
+
+
+@pytest.fixture(autouse=True, scope="module")
+async def create_test_database():
+    async with database:
+        await models.create_all()
+        yield
+        if not database.drop:
+            await models.drop_all()
+
+
+@pytest.fixture(autouse=True, scope="function")
+async def rollback_connections():
+    async with models.database:
+        yield
+
+
+class User(edgy.Model):
+    name: str = edgy.CharField(max_length=100, null=True)
+    email: str = edgy.EmailField(max_length=100, null=True)
+    language: str = edgy.CharField(max_length=200, null=True)
+    description: str = edgy.TextField(max_length=5000, null=True)
+
+    class Meta:
+        registry = models
+
+    def get_name(self) -> str:
+        return f"Details about {self.name}"
+
+
+class UserMarshall(Marshall):
+    marshall_config = ConfigMarshall(
+        model=User, fields=["name", "email", "language", "description"]
+    )
+    extra_context: fields.MarshallField = fields.MarshallMethodField(field_type=dict[str, Any])
+
+    def get_extra_context(self, instance) -> dict[str, Any]:
+        return self.context
+
+
+async def test_marshall_without_context():
+    data = {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+    }
+
+    user_marshalled = UserMarshall(**data)
+
+    assert user_marshalled.model_dump() == {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+        "extra_context": {},
+    }
+
+
+async def test_marshall_with_empty_context():
+    data = {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+    }
+
+    user_marshalled = UserMarshall(**data, context={})
+
+    assert user_marshalled.model_dump() == {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+        "extra_context": {},
+    }
+
+
+async def test_marshall_with_context():
+    data = {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+    }
+
+    user_marshalled = UserMarshall(**data, context={"foo": "bar"})
+
+    assert user_marshalled.model_dump() == {
+        "name": "Edgy",
+        "email": "[email protected]",
+        "language": "EN",
+        "description": "A description",
+        "extra_context": {"foo": "bar"},
+    }