ASP.NET Core minimal API's and parameter binding -> QueryString into a POCO (like how a Body goes into a POCO)?

Question

I'm trying to get my simple ASP.NET Core 7 minimal API to automatically bind the QueryString parameters into a single POCO.

Reference: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/parameter-binding?view=aspnetcore-7.0

For example:

https://localhost:5000/some/endpoint?a=1&b=hello&c=true

public record Query(int? A, string? B, bool? C); // Notice how all are optional!

public static async Task<Ok<List<Result>>> HandleAsync(
    Query query,
    MyDbContext myDbContext,
    HttpContext context,
    CancellationToken cancellationToken
)
{ .. }

If I do that, the framework is thinking/expecting the Query item to be [FromBody]. I've also tried this

[FromQuery] Query query,

but that also didn't work. (Unless I did something wrong).

Of course, this would work:

public static async Task<Ok<List<Result>>> HandleAsync(
    int? a,
    string? b,
    bool? c,
    MyDbContext myDbContext,
    HttpContext context,
    CancellationToken cancellationToken
)

but I don't want/like that. What can I try next?

What if you change the record into a class? Also try stackoverflow.com/questions/64794376/… — gunr2171
– gunr2171, Commented Sep 24, 2023 at 4:43
Have you seen this post? stackoverflow.com/questions/49741284/… — Ross Bush
– Ross Bush, Commented Sep 24, 2023 at 6:32

Guru Stron · Accepted Answer · 2023-09-28 18:27:17Z

2

Use AsParametersAttribute:

AsParametersAttribute enables simple parameter binding to types and not complex or recursive model binding.

public static async Task<Ok<List<Result>>> HandleAsync(
    [AsParameters] Query query,
    MyDbContext myDbContext,
    HttpContext context,
    CancellationToken cancellationToken
)
{
    ... 
}

answered Sep 28, 2023 at 18:27

Guru Stron

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2 Comments

Pure.Krome Over a year ago

and this should work when Query is a record ? also, Query is a "flat" record .. meaning all simple Types. no custom/complex classes as the properties.

Guru Stron Over a year ago

@Pure.Krome I have tested it with record (from your question).

SZT · Accepted Answer · 2023-09-24 10:11:34Z

0

If you change record to class it should work.

public class Query
{
    public int? A { get; set; }
    public string? B { get; set; }
    public bool? C { get; set; }
}

answered Sep 24, 2023 at 10:11

SZT

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