_get_signature() — fastapi Function Reference

Architecture documentation for the _get_signature() function in utils.py from the fastapi codebase.

Function python DependencyInjection ParamFunctions called by 2

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DependencyInjection→ ParamFunctions→ _get_signature() — fastapi Function Reference

Dependency Diagram

graph TD
  fbcdf484_be03_f18c_5e32_2ef21742686c["_get_signature()"]
  9e602cbf_3139_86ae_5666_97b8806942de["utils.py"]
  fbcdf484_be03_f18c_5e32_2ef21742686c -->|defined in| 9e602cbf_3139_86ae_5666_97b8806942de
  6a4e43ff_0eba_2bed_5c6f_cda57d19a022["get_typed_signature()"]
  6a4e43ff_0eba_2bed_5c6f_cda57d19a022 -->|calls| fbcdf484_be03_f18c_5e32_2ef21742686c
  7ee6f7cb_c895_d136_b942_3a323fcab521["get_typed_return_annotation()"]
  7ee6f7cb_c895_d136_b942_3a323fcab521 -->|calls| fbcdf484_be03_f18c_5e32_2ef21742686c
  style fbcdf484_be03_f18c_5e32_2ef21742686c fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

fastapi/dependencies/utils.py lines 201–216

def _get_signature(call: Callable[..., Any]) -> inspect.Signature:
    if sys.version_info >= (3, 10):
        try:
            signature = inspect.signature(call, eval_str=True)
        except NameError:
            # Handle type annotations with if TYPE_CHECKING, not used by FastAPI
            # e.g. dependency return types
            if sys.version_info >= (3, 14):
                from annotationlib import Format

                signature = inspect.signature(call, annotation_format=Format.FORWARDREF)
            else:
                signature = inspect.signature(call)
    else:
        signature = inspect.signature(call)
    return signature