Add .ctor(string) to FromHeaderAttribute and FromQueryAttribute

[martincostello]

Background and Motivation

When using Minimal APIs, using explicit query string or header parameter names using attributes requires a less-minimal amount of attribute declaration that would be possible if the relevant attributes did not only have a default constructor.

Proposed API

namespace Microsoft.AspNetCore.Mvc
{
    public static class FromHeaderAttribute
    {
+       public FromHeaderAttribute(string name)
    }

    public static class FromQueryAttribute
    {
+       public FromQueryAttribute(string name)
    }

    public static class FromRouteAttribute
    {
+       public FromRouteAttribute(string name)
    }
}

Usage Examples

using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/search", (
    [FromQuery("q")] string? query,
    [FromHeader("User-Agent")] string? userAgent) =>
{
    return $@"You searched for ""{query}"" using ""{userAgent}"".";
});

app.Run();

Alternative Designs

None, retain the existing usage patterns.

using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/search", (
    [FromQuery(Name = "q")] string? query,
    [FromHeader(Name = "User-Agent")] string? userAgent) =>
{
    return $@"You searched for ""{query}"" using ""{userAgent}"".";
});

app.Run();

Risks

None that I'm aware of.

EDIT: Added FromRouteAttribute too.

[rafikiassumani-msft]

Triage: We will evaluate this for .NET7

Thank you for submitting this for API review. This will be reviewed by @dotnet/aspnet-api-review at the next meeting of the ASP.NET Core API Review group. Please ensure you take a look at the API review process documentation and ensure that:

• The PR contains changes to the reference-assembly that describe the API change. Or, you have included a snippet of reference-assembly-style code that illustrates the API change.
• The PR describes the impact to users, both positive (useful new APIs) and negative (breaking changes).
• Someone is assigned to "champion" this change in the meeting, and they understand the impact and design of the change.

[pranavkm]

API review:
@martincostello while we think this API proposal is valid, we want to wait and see given a) a solution exists using the property (b) we might want to do something to not use MVC attributes with route handlers. We'll put this in our backlog for now and bring this back up part way thru 7.0 once we have had a better sense for how these attributes get used.