Combined [FromRoute] and [FromBody] confuses Swashbuckle

[ffMathy]

The reason I want a combined [FromRoute] and [FromBody] is because I am using the NuGet package Ardalis.ApiEndpoints, which forces your controller's action method to only have a single argument (a request type).

Ardalis.ApiEndpoints can be found here: https://github.com/ardalis/ApiEndpoints

For instance, consider the following code (EndpointBaseAsync inherits ControllerBase and also has an [ApiController] attribute on it):

public record Request(
    [FromRoute] Guid UserId,
    [FromBody] RequestBody Body);

public record RequestBody(
    string FirstName,
    string LastName);

public class UpdateUserEndpoint : EndpointBaseAsync
    .WithRequest<Request>
    .WithoutResult
{
    [HttpPut]
    [Route("users/{userId}")]
    public override async Task HandleAsync(
        [FromRoute] Request request,
        CancellationToken cancellationToken = default)
    {
        
    }
}

With the above, Swashbuckle generates this example. Notice how the FirstName and LastName properties incorrectly come from the "path", where as it should be a response body.

Accessing the endpoint from Postman works though. If I make the following request:

PUT /users/foobar
{
  "firstName": "Jonathan",
  "lastName": "Peterson"
}

And place a breakpoint, the request object correctly has all values (including both the route parameter and the body parameters).

But Swashbuckle should be recognizing that the firstName and lastName are part of the body, not path parameters.

Tested using latest dotnet (6.0) and latest Swashbuckle (6.2.3) as of writing.

More context (if interested): ardalis/ApiEndpoints#42

[ffMathy]

Workaround: If I change RequestBody and Request into classes, everything works as it should.

[nZeus]

Nice workaround.
I did a bit of investigation, and I know why it didn't work with the record types.

When you declare it like this:

public record Request(
    [FromRoute] Guid UserId,
    [FromBody] RequestBody Body);

you add attributes to the constructor parameters, not to the properties of your class/record.

So, in your case you could also keep it as a record, but declare it as:

public record Request
{
    [FromRoute] 
    public Guid UserId { get; init; }

    [FromBody]
    public RequestBody Body { get; init; } 
}

[github-actions]

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