How to snake_case requests with minimal api?

[Wuerike]

Hi!

I'm writing an application that requires both request paramenters and response body to be in snake_case

With the following code I've managed to serialize the response, but it doesn't affect the request deserialization.

builder.Services.Configure<JsonOptions>(options =>
{
    options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower;
});

Worth say that what I mean by request isn't the body, but the query parameters. At the endpoint I'm getting the query string with the AsParameters

I'm running 8.0.100-preview.6.23330.14

[moxplod]

Facing this exact issue today.

[davidfowl]

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/responses?view=aspnetcore-9.0#configure-json-serialization-options-globally

[moxplod]

I actually realized that my issue was the query string working differently than the global serialization options. As that uses model binding vs json serialization options. When I changed everything to snake case the document changed the request parameter to snake case as well. But it doesn’t deserialize correctly.

[seesharprun]

I have a minimal API that receives webhook events from GitHub.

If I use the configuration that @davidfowl suggested, I'm able to deserialize the body successfully into a C# POCO type:

builder.Services.ConfigureHttpJsonOptions(options =>
{
    options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower;
    options.SerializerOptions.PropertyNameCaseInsensitive = true;
});

app.MapPost(
    "/event-handler",
    async (
        [FromServices] IHandlerService handlerService,
        [FromBody] Payload payload
    ) => await handlerService.HandleAsync(payload));

My payload is just simple C# record types

sealed record Payload
{
    public required string Action { get; init; }

    public CheckSuite? CheckSuite { get; init; }

    public PullRequest? PullRequest { get; init; }
}

sealed record CheckSuite
{
    public required long Id { get; init; }
}

internal sealed record PullRequest
{
    public required long Id { get; init; }
}

Ideally, I want to use a JsonSerializerContext so I can configure the same serialization and deserialization context for model binding, HTTP client requests, and any service that wants to manually serialize/deserialize. But that doesn't seem to work:

[JsonSourceGenerationOptions(
    PropertyNamingPolicy = JsonKnownNamingPolicy.SnakeCaseLower,
    PropertyNameCaseInsensitive = true,
    UseStringEnumConverter = true)]
[JsonSerializable(typeof(Payload))]
internal sealed partial class GitHubJsonSerializerContext : JsonSerializerContext;

// Is invalid due to the property being read-only
builder.Services.ConfigureHttpJsonOptions(
    options => options.SerializerOptions = GitHubJsonSerializerContext.Default.Options
);

builder.Services.Configure<JsonSerializerOptions>(
    static o => o.TypeInfoResolver = GitHubJsonSerializerContext.Default
);

Am I forgetting something obvious? The SerializerOptions property is read-only, so I can only set a single property at a time. This is as far as I got:

builder.Services.ConfigureHttpJsonOptions(
    static options => options.SerializerOptions.TypeInfoResolver = GitHubJsonSerializerContext.Default
);

Unfortunately this leaves the naming convention to JsonNamingPolicy.CamelCase. ☹️

[martincostello]

This doesn't answer your question directly, but have you considered using the Octokit.Webhooks.AspNetCore NuGet package?

This provides an endpoint to receive the webhooks, signature validation of the payloads if needed, comes with all the POCOs you need and handles all the serialization for you.

[seesharprun]

I will investigate that package. I was building it all out manually. Thankfully, building it out manually was a useful exercise to help me understand how each webhook works internally :-).

Thanks!