C#•11mo ago

Binding case-insensitive query parameter to string enum in .NET 9 Minimal API

I have an

order

order

query parameter that I'd like to bind to an

Order

Order

enum in a minimal API endpoint (

[FromQuery] Order order = Order.Desc

[FromQuery] Order order = Order.Desc

[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Order
{
    [JsonStringEnumMemberName("asc")] Asc,

    [JsonStringEnumMemberName("desc")] Desc
}

[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Order
{
    [JsonStringEnumMemberName("asc")] Asc,

    [JsonStringEnumMemberName("desc")] Desc
}

I'd like to accept all values like "ASC", "asc", "Asc", but currently only "Asc" and "Desc" work. I get a bad request with

Microsoft.AspNetCore.Http.BadHttpRequestException: Failed to bind parameter "Order order" from "desc".

Microsoft.AspNetCore.Http.BadHttpRequestException: Failed to bind parameter "Order order" from "desc".

Thalnos•1/28/25, 12:32 PM

one way to do this is to create a custom modelbinder https://learn.microsoft.com/en-us/aspnet/core/mvc/advanced/custom-model-binding?view=aspnetcore-9.0

Thalnos•1/28/25, 12:32 PM

I dont think you can make the default modelbinder case insensitive

Thalnos•1/28/25, 12:35 PM

mhm actually screw that, I'm reading right now that the default model binding in asp.net core is case insensitive by default o.O

Thalnos•1/28/25, 12:44 PM

oh I think I understand why its not working.

holds but the fields in an enum aren't properties. You can only make property binding case insensitive it seems. Consider changing your enum to a class,record or struct to make it case insensitive