URL Query params should be hinted as "form", not "json"

[djeer]

I've run into in issue that my parsed query params are always nil. It was resolved by manually changing query params hint from "json" to "form" in the generated types. The problem may be reproduced using petstore-expanded.yaml, generated code (not working):

type FindPetsParams struct {
	// tags to filter by
	Tags *[]string `json:"tags,omitempty"`

	// maximum number of results to return
	Limit *int32 `json:"limit,omitempty"`
}

code I expect to be generated (working):

type FindPetsParams struct {
	// tags to filter by
	Tags *[]string `form:"tags,omitempty"`

	// maximum number of results to return
	Limit *int32 `form:"limit,omitempty"`
}

Code I am using to parse query params:

func ParseFilter(c *gin.Context) (myapi.FindPetsParams, error) {
	f := tasksapi.FindPetsParams{}
	if err := c.BindQuery(&f); err != nil {
		return f, err
	}
	return f, nil
}

[djeer]

I've found exact place where it is generated https://github.com/deepmap/oapi-codegen/blob/master/pkg/codegen/schema.go#L447

if p.Required || p.Nullable || !omitEmpty {
	fieldTags["json"] = p.JsonFieldName
} else {
	fieldTags["json"] = p.JsonFieldName + ",omitempty"
}

[djeer]

Checked the code from master branch, auto-generated server reads query parameters as "form", so it's just annotations that are wrong representing them as "json" (annotations are not used by generated server). Created PR to fix this. Build passed green.

[deepmap-marcinr]

The annotation on those fields isn't related to the parameter type in BindQueryParameter. There is something missing in the problem description. By changing the annotation to form:"...", you are changing the way JSON is parsed, so perhaps that's changing things up in a way that make them work.

[deepmap-marcinr]

Oh, I see what's going on.

We need both annotations, then, both form and json on those objects.

Perhaps we add the form annotation for gin.

[djeer]

@deepmap-marcinr I want to clarify, an auto-generated server works fine since it generates boilerplate code using BindQueryParameter and not using any annotations. But we are not using an auto-generated server and therefore the annotations are needed for BindQuery to work if we want to parse all parameters without writing much code. It was not clear at first why they are always nil.

Both form and json annotations should work fine. Thanks.

[djeer]

Very nice, thanks!