[OpenAPI] Integers represented as both integer/string even when AddJsonOptions sets NumberHandling to Strict

[IGx89]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

In order to configure a controller API app to both accept only numbers for integer properties and represent them as only integers (and not integer/strings) in the OpenAPI document, JSON options have to be configured in two places:

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;
});

Typically only one or the other are configured (former for controller-based APIs and the latter for minimal APIs). Is that intentional or a bug that OpenAPI ignores Microsoft.AspNetCore.Mvc.JsonOptions?

Related to #61038

Expected Behavior

NumberHandling only needs to be set to strict on Microsoft.AspNetCore.Mvc.JsonOptions to cause OpenAPI to report number fields as not strings.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

10.0.100-rc.2.25502.107

Anything else?

No response

[martincostello]

Typically only one or the other are configured (former for controller-based APIs and the latter for minimal APIs). Is that intentional or a bug that OpenAPI ignores Microsoft.AspNetCore.Mvc.JsonOptions?

This is intentional - Minimal APIs cannot depend on MVC's JSON options type as it is lower in the stack, so it has its own JSON options type.

OpenAPI similarly uses the Minimal API JSON options type so that it is not dependent on MVC.

[IGx89]

Thanks for confirming! I imagine this question is going to come up a lot as people upgrade their MVC APIs (when they read that they should set NumberHandling to Strict they're going to first try it in AddJsonOptions, since that's how they're used to configuring their JSON options), so at least it's now documented here :)

[pietersap]

Yes thank you, this was helpful

[SnapperGee]

This was extremely helpful, thank you! If the default behavior could be fixed to represent numeric types as just numbers that'd make the dx experience much better and more predictable and intuitive!