[BUG] references to external files does not work

[YishTish]

Description

Generating code with references to external files does not work (used to work in V2).

stack trace (last lines):

> [main] WARN  o.o.codegen.utils.ModelUtils - Failed to get the schema name: ./event.json#/schemas/event
Exception in thread "main" org.openapitools.codegen.SpecValidationException: There were issues with the specification. The option can be disabled via validateSpec (Maven/Gradle) or --skip-validate-spec (CLI).
 | Error count: 1, Warning count: 0
Errors:
	-null

	at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput(CodegenConfigurator.java:606)
	at org.openapitools.codegen.cmd.Generate.run(Generate.java:395)
	at 

> org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:60)

openapi-generator version

4.0.2

OpenAPI declaration file content or url

https://gist.github.com/YishTish/d2f8335e6027f4d50beec84abdf20b90

Command line used for generation

regular bash: openapi-generator generate -i openapi.json -g openapi-yaml -o generated/

Steps to reproduce

Just run the code with the jsons specified.

Related issues/PRs

#3026

Suggest a fix

When $ref starts with './', change behaviour to pick up the data from external file. Note that the file location is always relative, and absolute path can (should?) be considered wrong.

[jmini]

I fear that this is an issue with Swagger-Parser.

Since your example is quite big, it take some times to understand which part is broken.

[DonDi94]

I encountered the same problem and it is indeed something about Swagger-Parser.

To be more precise, I have had this problem when 1) defining content with reference schema for parameters and 2) referencing a requestBody component that has an external schema reference which also references another schema.

#test.yaml
openapi: 3.0.0
info:
    version: "1.0"
    title: Swagger Parser Issue
paths:
  /:
    post:
      parameters:
        - name: param
          in: query
          required: true
          content:
            'application/json':
              schema:
                $ref: 'common.yaml#/components/schemas/ExternalSchema'
      requestBody:
        $ref: '#/components/requestBodies/RefRequestBody'
      responses:
        default:
          description: "Error"
components:
  requestBodies:
    RefRequestBody:
      required: true
      content:
        'application/json':
          schema:
            $ref: 'common.yaml#/components/schemas/ExternalSchema'

#common.yaml                          
openapi: 3.0.0
info:
    version: "1.0"
    title: Swagger Parser Issue
paths: {}
components:
  schemas:
    AnotherSchema:
      type: string
    ExternalSchema:
      type: object
      properties:
        val:
          $ref: '#/components/schemas/AnotherSchema'

[jmini]

@DonDi94:

We are using:

    <dependency>
        <groupId>org.openapitools.swagger.parser</groupId>
        <artifactId>swagger-parser</artifactId>
        <version>2.0.13-OpenAPITools.org-1</version>
    </dependency> 

and swagger-parser did publish an update recently.
I can not reproduce the problem anymore with:

    <dependency>
        <groupId>io.swagger.parser.v3</groupId>
        <artifactId>swagger-parser</artifactId>
        <version>2.0.13</version>
    </dependency>

Test program:

import io.swagger.parser.OpenAPIParser;
import io.swagger.v3.core.util.Yaml;
import io.swagger.v3.oas.models.OpenAPI;
import io.swagger.v3.parser.core.models.ParseOptions;

public class SwaggerParserMain {

	public static void main(String[] args) throws Exception {
		final String inputSpec = "<your file>";

		OpenAPIParser openApiParser = new OpenAPIParser();
		ParseOptions options = new ParseOptions();
		options.setResolve(true);
		options.setFlatten(true);

		OpenAPI openAPI = openApiParser.readLocation(inputSpec, null, options).getOpenAPI();
		String string = Yaml.mapper().writerWithDefaultPrettyPrinter().writeValueAsString(openAPI);

		System.out.println(string);
	}
}

We discussed already that we would like to update. I will see if we can do a 2.0.13-OpenAPITools.org-2 release.

@YishTish: I did not look, but I hope your problem is the same.

[jmini]

I have started #3239

[YishTish]

I've made some changes to the files in the gist. Apparently, there were some schema issues with them that I didn't realize.
The updated jsons are valid. I found an npm package (json-schema-ref-parser) that replaces the $refs with the data that is referenced, and that worked (got a python-flask project generated)

[jmini]

@YishTish & @DonDi94: we have updated the Swagger-Parser version we are using. Can you retry your cases with a recent 4.0.3-SNAPSHOT version?
(it should now work with the $refs as discussed, no need to replace them before using OpenAPI-Generator)

[DonDi94]

@jmini for my use now it works fine, the referenced schemes for parameters with content are referenced correctly. I do have a bug to report though, as this case that I was using for testing is still not working.

#test.yaml
openapi: 3.0.0
info:
    version: "1.0"
    title: Swagger Parser Issue
paths:
  /:
    post:
      requestBody:
        $ref: '#/components/requestBodies/RefRequestBody'
      responses:
        default:
          description: "Error"
components:
  requestBodies:
    RefRequestBody:
      content:
        'application/json':
          schema:
            $ref: 'common.yaml#/components/schemas/StringObject'

With the external reference pointing to

#common.yaml                          
openapi: 3.0.0
info:
    version: "1.0"
    title: Swagger Parser Issue
paths: {}
components:
  schemas:
    String:
      type: string
    StringObject:
      type: object
      properties:
        val:
          $ref: '#/components/schemas/String'

This example results in StringObject failing to get the reference for String

"StringObject" : {
  "type" : "object",
  "properties" : {
    "val" : {
      "$ref" : "./common.yaml#/components/schemas/String"
    }
  },
  "example" : {
    "val" : "{}"
  }
},

[jmini]

@DonDi94: thank you a lot for your example.

IMO this is definitively an error produced by Swagger-Parser (that merges for us all separated files into a single one). I have raised swagger-api/swagger-parser#1147 with your example.

[DonDi94]

@jmini no problem I'm glad to help! Yes I agree, the previously reported problem was for the exact same issue in referenced schemes in parameter's contents. In that case I was getting the same result with the .common.yaml/... in the processed JSON for parameters.

[jmini]

swagger-api/swagger-parser#1147 seems to be fixed in swagger-parser and we did an update in OpenAPI-Generator to use this new version (see #3737)

@DonDi94: Can you try with the latest 4.1.1-SNAPSHOT ?

[DonDi94]

swagger-api/swagger-parser#1147 seems to be fixed in swagger-parser and we did an update in OpenAPI-Generator to use this new version (see #3737)

@DonDi94: Can you try with the latest 4.1.1-SNAPSHOT ?

I tested on the previous case and it works, all the references are resolved correctly.