OpenApi default number types

[johnnyreilly]

Background and Motivation

I've recently been writing up using.NET OpenAPI support combined with openapi-ts:

https://johnnyreilly.com/dotnet-openapi-and-openapi-ts

It's worked out well, but the default choice for numbers, specifically integers seems peculiar:

"temperatureC": {
            "pattern": "^-?(?:0|[1-9]\\d*)$",
            "type": ["integer", "string"],
            "format": "int32"
          },

Here an integer is surfaced as an integer or a string. This seems like a surprising choice. It can be worked around with custom IOpenApiSchemaTransformers:

https://johnnyreilly.com/dotnet-openapi-and-openapi-ts#adjusting-microsoftaspnetcoreopenapi-surfaced-types

But it's surprising this is necessary in the first place.

I'm wondering if the default transformers make the most sense? Would they be more useful if they were more along the lines of the customised examples in my post?

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• [OpenAPI] integers have additional string type with pattern #61038
• OpenAPI long props are generated as integer | string types with a regex pattern #62963
• Microsoft.OpenAPI 2.0 adds string type with pattern for int params. How to avoid? #64473
• [OpenAPI] Integers represented as both integer/string even when AddJsonOptions sets NumberHandling to Strict #64145

[TsengSR]

Had the same issue with methods using parameters of type long.

This had severe impact on SwaggerUI validation, always triggering the path segments as invalid and that "this parameter is requried".

I opened the issue here but obviously it was the wrong place. This really needs to be addressed, as it severely impacts the usability of SwaggerUI and possibly all other TypeScript/JavaScript based clients.

The workaround fixes this

builder.Services.AddOpenApi(options =>
{
    options.AddSchemaTransformer((schema, context, cancellationToken) =>
    {
        if (schema.Format == "int64" && schema.Type.HasValue)
        {
            schema.Type = JsonSchemaType.Integer;
        }
        return Task.CompletedTask;
    });
}

but its not pretty to have to do it in every project. In the specifc case, this happens on action paths including long, as in

    [HttpPut("{projectId}/active")]
    public async Task<ActionResult<Project>> IsActive([Range(0, long.MaxValue)] long projectId)
    {
    }

and happens independently of [Range(0, long.MaxValue)] annotation.

[SnapperGee]

I came across the same (imo odd and unexpected) behavior as well and found this issue opened previously with a relatively clean and elegant solution:

#64145

You need to set JSON options both in builder.Services.AddController().AddJsonOptions(...) AND builder.Services.ConfigureHttpJsonOptions(...). Copied from the issue I linked above:

builder.Services
	.AddControllers()
	.AddJsonOptions(options =>
	{
		// Tell controllers to not accept strings for number fields
		options.JsonSerializerOptions.NumberHandling = JsonNumberHandling.Strict;
	});

builder.Services.ConfigureHttpJsonOptions(options =>
{
	// Tell OpenApi generator to report number fields as integers/floats only, not strings
	options.SerializerOptions.NumberHandling = JsonNumberHandling.Strict;
});