Header parameters are declared the same way as Query and Path parameters:
--8<-- "docs_src/tutorial/header_params/tutorial_001.py"Headers names are usually composed of several words separated by hyphens ("-").
But Python veriable names cannot contain hyphens.
Since Xpresso automatically derives the header names from the parameter names, this creates a problem.
To get around this, Xpresso automatically converts parameter name underscores ("_") to hyphens ("-").
This is controlled using the convert_underscores parameter to HeaderParam(...):
--8<-- "docs_src/tutorial/header_params/tutorial_002.py"!!! tip "Tip"
The import from Xpresso.typing import Annotated is just a convenience import.
All it does is import Annotated from typing if your Python version is >= 3.9 and [typing_extensions] otherwise.
But if you are already using Python >= 3.9, you can just replace that with from typing import Annotated.
!!! warning "Warning"
It is pretty uncommon to use headers with underscores.
You should probably think twice about setting convert_underscores=False and test that it doesn't break your clients, proxies, etc.