[release/9.0] Fix ModelMetadata for TryParse-parameters in ApiExplorer

[captainsafia]

Description

This PR fixes the handling for schemas associated with types that implement a custom TryParse and are consumed from either the route or query string.

Fixes #58318

Customer Impact

Without this change, APIs that bind parameters from the query string or URL will produce invalid schemas if the type being bound to implements a TryParse method or the IParsable interface.

There are workarounds for this scenario (using schema transformers) but it requires users add a fair bit of code in their own applications and this fix is small enough to warrant improving the QoL for this.

Example of impacted scenario

app.MapGet("/student/{student}", (Student student) => $"Hi {student.Name}");

public record Student(string Name)
{
    public static bool TryParse(string value, out Student? result)
    {
        if (value is null)
        {
            result = null;
            return false;
        }

        result = new Student(value);
        return true;
    }
}

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Change localized to OpenAPI support + TryParsable parameters in the route query.

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

[captainsafia]

Approved via email.

[wtgodbe]

@captainsafia can you resolve the merge conflict?

[captainsafia]

@wtgodbe Done!

@BrennanConroy Can you take a look at this backport? Thanks!

[Phalelashvili]

could this be the solution for issue where unbound route parameter changes schema type of other action after caching it? in my sample, it has nothing to do with IParsable. I figure JsonNode reference gets modified after it's cached by OpenApiSchemaStore

using System.Text.Json.Nodes;
using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddControllers();
builder.Services.AddOpenApi();

var app = builder.Build();
app.MapOpenApi();

app.MapControllers();
app.MapDefaultControllerRoute();

app.Run();

[ApiController]
[Route("api/test")]
public class TestController : ControllerBase
{
    /// <summary>
    /// method that's defined properly.
    /// but open api generates parameter value as long (from broken method) instead of string
    /// only AFTER first call to openapi explorer. next time OpenApiSchemaStore returns incorrect cached value
    /// NOTE: if parameter in this method was not a complex object, it would have been fine.
    /// </summary>
    [HttpGet("search")]
    public IActionResult Search([FromQuery] SearchQuery query) => Ok();

    /// <summary>
    /// this is the method that breaks other actions.
    /// it defines a route parameter {id:long} in template but does not have parameter to bind it to.
    /// NOTE: not specifying type of id will not break other actions.
    /// </summary>
    [HttpGet("{id:long}/broken-method")]
    public IActionResult BrokenMethod() => Ok();
}

public class SearchQuery
{
    public string Term { get; init; }
}

[captainsafia]

@Phalelashvili I think what you're seeing is a different issue. I believe there's a difference in behavior between MVC and Minimal APIs where route parameters not associated with a method parameter don't materialize in the ApiExplorer model. Can you file an issue for this?