Add support for location='view_args'

[teodorkostov]

To validate path arguments with webargs the location value that has to be used is view_args. Documentation link.

The following code

from webargs.flaskparser import use_args
@use_args(IdSchema, location='view_args')

should be possible to be written as

from apiflask import APIFlask
app = APIFlask(__name__)
@app.input(IdSchema, location='view_args')

[greyli]

Thanks for reporting on this. I will add the path and view_args locations later.

I have some doubts about this. If a view accepts a path schema, then the view function will have to declare both the path variables (one by one) and the path schema data:

@app.get('/pets/<id>/<name>/<category>')
@app.input(PathSchema, location='path')
def hello(id, name, category, path_data):
    ...

Is it the correct usage?

[teodorkostov]

@greyli Correct. Unfortunately, the path_data is passed as another dictionary after all the path arguments. I do not know the reasoning behind it but this is the implementation from webargs.

Thank you for this fix!