HttpGet [FromQuery] Model binding fails in case of propertity with the same name

[FatTigerWang]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Model binding fails when a [FormQuery] parameter has the same name as a property of the model.

public class TestParameter 
{
    public string Parameter { get; set; };
}

[ApiController]
public class TestController()
{
        [HttpGet("test")]
        public TestParameter Test([FromQuery] TestParameter parameter)
        {
            return parameter;
        }
}

HTTP GET /test?Parameter=test

{
  "parameter": null
}

Looks like it's related to here

aspnetcore/src/Mvc/Mvc.Core/src/ModelBinding/ParameterBinder.cs

Line 121 in c4601ad

else if (modelBindingContext.ValueProvider.ContainsPrefix(parameter.Name))

When the name of the model is the same as the model attribute name, the binding intention cannot be easily determined by the prefix

Expected Behavior

HTTP GET /test?Parameter=test

{
  "parameter": "test"
}

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

9.0.100-preview.7.24407.12

Anything else?

No response

[sami-daniel]

Hello. I'm going to work on it. Can I get this one for myself?

[mitchdenny]

PRs welcome

[codelovercc]

I'm facing the same issue. The ValidationProblemDetails error keys also contains the model parameter name prefix, in .net 8, there's no prefixes, in .net 9 this makes my test cases failed.

The prefix behavior changes makes me a lot of work to do while update .net 8 to .net 9. I have to modify my test cases and custom error keys, the Front-End apps have to update to follow up these changes as well.

[sami-daniel]

Hi, @codelovercc
A few months ago, I made a PR that solved this problem. But for some reason, the CI tests failed in unrelated tests (E.g Identity tests) but not in the context of the test case or other related test case. I'm gonna ask to run again the pipeline to see If the behavior is the same.