Dependant

This class represents a structured model for managing dependencies and their associated parameters, such as path, query, header, and body fields. It tracks nested dependencies, security scopes, and the execution context of a callable to determine its lifecycle and caching behavior. Additionally, it provides utilities to identify the nature of the callable, including whether it is a coroutine, generator, or asynchronous generator.

Attributes

Attribute	Type	Description
path_params	list[ModelField] = []	List of model fields representing parameters extracted from the URL path.
query_params	list[ModelField] = []	List of model fields representing parameters extracted from the URL query string.
header_params	list[ModelField] = []	List of model fields representing parameters extracted from the HTTP request headers.
cookie_params	list[ModelField] = []	List of model fields representing parameters extracted from the HTTP cookies.
body_params	list[ModelField] = []	List of model fields representing parameters extracted from the HTTP request body.
dependencies	list[[Dependant](dependant.md?sid=fastapi_dependencies_models_dependant)] = []	List of other Dependant objects that this dependency relies on.
name	`str	None` = null
call	`Callable[..., Any]	None` = null
request_param_name	`str	None` = null
websocket_param_name	`str	None` = null
http_connection_param_name	`str	None` = null
response_param_name	`str	None` = null
background_tasks_param_name	`str	None` = null
security_scopes_param_name	`str	None` = null
own_oauth_scopes	`list[str]	None` = null
parent_oauth_scopes	`list[str]	None` = null
use_cache	bool = true	Determines whether the result of the dependency should be cached for the duration of the request.
path	`str	None` = null
scope	`Literal['function', 'request']	None` = null

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Constructor

Signature

def Dependant(
    path_params: list[ModelField] = [],
    query_params: list[ModelField] = [],
    header_params: list[ModelField] = [],
    cookie_params: list[ModelField] = [],
    body_params: list[ModelField] = [],
    dependencies: list[[Dependant](dependant.md?sid=fastapi_dependencies_models_dependant)] = [],
    name: str | None = null,
    call: Callable[..., Any]| None = null,
    request_param_name: str | None = null,
    websocket_param_name: str | None = null,
    http_connection_param_name: str | None = null,
    response_param_name: str | None = null,
    background_tasks_param_name: str | None = null,
    security_scopes_param_name: str | None = null,
    own_oauth_scopes: list[str]| None = null,
    parent_oauth_scopes: list[str]| None = null,
    use_cache: bool = true,
    path: str | None = null,
    scope: Literal['function', 'request']| None = null
) - > null

Parameters

Name	Type	Description
path_params	list[ModelField] = []	List of path parameters for the dependency.
query_params	list[ModelField] = []	List of query parameters for the dependency.
header_params	list[ModelField] = []	List of header parameters for the dependency.
cookie_params	list[ModelField] = []	List of cookie parameters for the dependency.
body_params	list[ModelField] = []	List of body parameters for the dependency.
dependencies	list[[Dependant](dependant.md?sid=fastapi_dependencies_models_dependant)] = []	List of sub-dependencies required by this dependency.
name	`str	None` = null
call	`Callable[..., Any]	None` = null
request_param_name	`str	None` = null
websocket_param_name	`str	None` = null
http_connection_param_name	`str	None` = null
response_param_name	`str	None` = null
background_tasks_param_name	`str	None` = null
security_scopes_param_name	`str	None` = null
own_oauth_scopes	`list[str]	None` = null
parent_oauth_scopes	`list[str]	None` = null
use_cache	bool = true	Whether to cache the result of this dependency.
path	`str	None` = null
scope	`Literal['function', 'request']	None` = null

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Methods

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oauth_scopes()

@classmethod
def oauth_scopes() - > list[str]

Aggregates all OAuth2 scopes required by this dependency and its parents. It preserves the order of scopes while ensuring uniqueness.

Returns

Type	Description
list[str]	A list of unique OAuth2 scope strings required for authorization.

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cache_key()

@classmethod
def cache_key() - > DependencyCacheKey

Generates a unique identifier used to cache the result of the dependency execution. The key is composed of the callable, relevant OAuth scopes, and the execution scope.

Returns

Type	Description
DependencyCacheKey	A tuple containing the callable, sorted scopes, and scope string used for cache lookups.

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is_gen_callable()

@classmethod
def is_gen_callable() - > bool

Detects if the dependency callable is a standard Python generator function. It inspects the callable and its call method to support both functions and classes.

Returns

Type	Description
bool	True if the callable is a synchronous generator, otherwise False.

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is_async_gen_callable()

@classmethod
def is_async_gen_callable() - > bool

Detects if the dependency callable is an asynchronous generator function. This is used to determine if the dependency requires an async context manager for execution.

Returns

Type	Description
bool	True if the callable is an async generator, otherwise False.

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is_coroutine_callable()

@classmethod
def is_coroutine_callable() - > bool

Detects if the dependency callable is a coroutine function (async def). This helps the framework decide whether to await the dependency call.

Returns

Type	Description
bool	True if the callable is an awaitable coroutine function, otherwise False.

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computed_scope()

@classmethod
def computed_scope() - > str | None

Calculates the lifecycle scope of the dependency based on its type. It defaults to 'request' for generator-based dependencies to ensure proper cleanup.

Returns

Type	Description
`str	None`

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