Breaking swagger spec into multiple files with $ref causes nil pointer dereference.

[Chris Langager]

We are attempting to break a large swagger file into multiple files for ease of management. Here's a simple example that replicates this issue:

splitSwaggerSpec.json:

{
  "swagger": "2.0",
  "info": {
    "title": "Testing out splitting up swagger spec into multiple files",
    "version": "v1"
  },
  "paths": {
  },
  "definitions": {
    "user": {
      "$ref": "./splitSwaggerSpecUserDefinition.json"
    }
  }
}

splitSwaggerSpecUserDefinition.json:

{
  "type": "object",
  "properties": {
    "name": {
      "type": "string"
    }
  }
}

spec, err := loads.Spec("./splitSwaggerSpec.json")
// spec.Spec().Definitions["user"].SchemaProps.Ref is set to ./splitSwaggerSpecUserDefinition.json, however no other SchemaProps are set

//attempting to Expand the spec results in a panic
expandedSpec , err = spec.Expanded()

This is the panic:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x695d1]

goroutine 1 [running]:
github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/spec.expandSchema(0x0, 0x0, 0x0, 0xc8202c4380, 0x0, 0x0, 0x0, 0x100, 0x0, 0x0, ...)
    /Users/chris.langager/go/src/github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/spec/expander.go:442 +0x4f1
github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/spec.ExpandSpec(0xc820327300, 0x0, 0x0)
    /Users/chris.langager/go/src/github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/spec/expander.go:325 +0x28a
github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/loads.(*Document).Expanded(0xc8203a7840, 0x1, 0x0, 0x0)
    /Users/chris.langager/go/src/github.com/khelldar/SwaggerToServer/vendor/github.com/go-openapi/loads/spec.go:140 +0xe1
main.main()
    /Users/chris.langager/go/src/github.com/khelldar/SwaggerToServer/main.go:94 +0x1c5

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /usr/local/go/src/runtime/asm_amd64.s:1721 +0x1

Is it possible to expand references that are across different .json or .yaml files? If not, I would be willing to add this as a feature, provided you are accepting pull requests on this project.

[Ivan Porto Carrero]

I would be willing to add this, but it is against the ref spec IIRC

we use something like this in a pre-generate step

#!/bin/bash

# Background
# go-swagger doesn't handle external definition reference well in generated
# go code. It doesn't generate anything regarding the models which causes
# problems if the models are generated in a separated package.
# The solution is to merge the models into swagger file then go-swagger is able
# to generate the reference to the models with right package name.
# Before go-swagger handles well with JSON references, this script is a
# workaround to make our swagger spec look better.

SPEC_DIR="$1"
API_SPEC="$2"
API_SPEC_FILE="$SPEC_DIR/$API_SPEC-swagger.yml"
MODEL_SPEC_FILE="$SPEC_DIR/models-swagger.yml"

combine() {
  cat "$API_SPEC_FILE"
  if grep 'definitions:' "$API_SPEC_FILE" >/dev/null 2>&1 ; then
    grep -v 'swagger:' "$MODEL_SPEC_FILE" | grep -v 'definitions:'
  else
    grep -v 'swagger:' "$MODEL_SPEC_FILE"
  fi
}

combine | sed 's#./models-swagger.yml##g' >$API_SPEC-swagger.gen.yml

[Ivan Porto Carrero]

I do think it would be helpful to have especially because refs do support http urls