Resolve Refs in OpenAPI3 spec

go.mod

module testmodule

go 1.21.0

require github.com/getkin/kin-openapi v0.120.0

require (
	github.com/go-openapi/jsonpointer v0.19.6 // indirect
	github.com/go-openapi/swag v0.22.4 // indirect
	github.com/invopop/yaml v0.2.0 // indirect
	github.com/josharian/intern v1.0.0 // indirect
	github.com/mailru/easyjson v0.7.7 // indirect
	github.com/mohae/deepcopy v0.0.0-20170929034955-c48cc78d4826 // indirect
	github.com/perimeterx/marshmallow v1.1.5 // indirect
	gopkg.in/yaml.v3 v3.0.1 // indirect
)

main.go

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/getkin/kin-openapi/openapi3"
)

func main() {
	contents, err := os.ReadFile("foo.json")
	if err != nil {
		log.Fatal(err)
	}

	doc, err := openapi3.NewLoader().LoadFromData(contents)
	if err != nil {
		log.Fatal(err)
	}

	// kin already resolves internal refs by default,
	// however when marshalling back to JSON it prefers
	// to output the ref if it's set; to prevent this,
	// we walk through the document and remove all refs;
	// NB: This might result in an inifite loop if your
	// spec had circular references.
	derefSchemas(doc.Components.Schemas)

	j, err := doc.MarshalJSON()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(string(j))
}

func derefSchemas(schemas openapi3.Schemas) {
	for _, schemaRef := range schemas {
		derefSchemaRef(schemaRef)
	}
}

func derefSchemaRefs(schemaRefs openapi3.SchemaRefs) {
	for _, schemaRef := range schemaRefs {
		derefSchemaRef(schemaRef)
	}
}

func derefSchemaRef(schemaRef *openapi3.SchemaRef) {
	if schemaRef == nil {
		return
	}

	schemaRef.Ref = ""

	val := schemaRef.Value

	derefSchemaRefs(val.OneOf)
	derefSchemaRefs(val.OneOf)
	derefSchemaRefs(val.AllOf)
	derefSchemaRef(val.Not)
	derefSchemaRef(val.Items)
	derefSchemas(val.Properties)
	derefSchemaRef(val.AdditionalProperties.Schema)
}