🐛 Fix edge case with repeated aliases names not shown in OpenAPI

[klaa97]

Currently, routes' parameters defined in multiple dependencies are not duplicated since only one parameter per position (path, query, headers, cookie) is retrieved. The current solution has the caveat of not identifying parameters with the same alias, but different position.

Problem example
Example of parameters shown in the current FastAPI Schema for the given route:

@app.get("/{repeated_alias}")
def get_parameters_with_repeated_aliases(
    path: str = Path(..., alias="repeated_alias"),
    query: str = Query(..., alias="repeated_alias"),
):
    return {"path": path, "query": query}

'parameters': [{'in': 'query',
                                               'name': 'repeated_alias',
                                               'required': True,
                                               'schema': {'title': 'Repeated '
                                                                   'Alias',
                                                          'type': 'string'}}]

Solution
To fix the name clashing, it is sufficient to consider parameters duplicated only if they have the same alias and the same type.

The OpenAPI generated by the PR solution is:

"parameters": [
                    {
                        "in": "path",
                        "name": "repeated_alias",
                        "required": True,
                        "schema": {"title": "Repeated " "Alias", "type": "string"},
                    },
                    {
                        "in": "query",
                        "name": "repeated_alias",
                        "required": True,
                        "schema": {"title": "Repeated " "Alias", "type": "string"},
                    },
                ]

[codecov]

Codecov Report

Merging #2351 (2f2a1ae) into master (3a3b61d) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #2351   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          532       533    +1     
  Lines        13684     13701   +17     
=========================================
+ Hits         13684     13701   +17     

Impacted Files	Coverage Δ
fastapi/openapi/utils.py	100.00% <ø> (ø)
tests/test_repeated_parameter_alias.py	100.00% <100.00%> (ø)

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[github-actions]

📝 Docs preview for commit 2078360926f56483db28a5a66c9fc9d1e610c8fc at: https://5fafc65b048ac31efbfc9ef8--fastapi.netlify.app

[github-actions]

📝 Docs preview for commit 8d5fc97 at: https://5fafc9c1048ac31bf9fc9f69--fastapi.netlify.app

[falkben]

maybe i'm a bit dense, but why do you need the same alias to a query and a path param?

[klaa97]

maybe i'm a bit dense, but why do you need the same alias to a query and a path param?

Thank you, the path param and query is a corner case indeed and easily solvable by just changing the name of the query param (which is an implementation detail). On the other hand, consider a combination of query/cookie/header parameter. I agree it can be a corner case, but it is not an implementation detail and may be a particular requirement for an API to expose

[github-actions]

📝 Docs preview for commit 329cc33 at: https://62fe9f757e6f0d007c146366--fastapi.netlify.app

[tiangolo]

Thanks @klaa97! 🍰

I don't see an obvious use case that needs this, but it also doesn't hurt, so I'm accepting it. 😄

I updated the branch and the test with some recent updates.

Thanks for the contribution! ☕

And thanks for the input @falkben! 🤓