Read APIError response body

[mxinden]

I make a request via a client generated based on a swagger spec generated via the goswagger.io project with an invalid json property. The back-end returns a HTTP 422 with details in the response body. Reading the response body is crucial to debug the problem.

go-openapi/runtime/client/runtime.go.Submit() calls readResponse.ReadResponse which returns an APIError with the response body embedded:

runtime/client/runtime.go

Line 422 in 231d787

return readResponse.ReadResponse(response{res}, cons)

runtime/client_response.go

Lines 55 to 59 in 231d787

	type APIError struct {
	OperationName string
	Response interface{}
	Code int
	}

Problem is, that this embedded response body is closed via a defer in go-openapi/runtime/client/runtime.go.Submit():

runtime/client/runtime.go

Line 395 in 231d787

defer res.Body.Close()

Thereby casting the error and reading the response body later on fails with http: read on closed response body:

apiError, ok := err.(*runtime.APIError)
if !ok {
	// handle
}

response, ok := apiError.Response.(runtime.ClientResponse)
if !ok {
	// handle
}

body, err := ioutil.ReadAll(response.Body())
if err != nil {
	// fails with "http: read on closed response body"
}

fmt.Println(string(body))

How can I access the APIError response body? Might it be possible to embed the body as a string inside the APIError? Let me know if you need more info.

[mxinden]

@casualjim any thoughts on this?

[bdazl]

I'm having problem with this also. As an outsider of this project, it seems like the func (*APIError) Error() should handle this similarly to how @mxinden handles the error (with some fix to the stated error). To me, the error provided by this function is not sufficient.

[casualjim]

you have to provide the error datastructure in the definitions, so that it gets picked up
or put a schema of type: object for the response body schema

the mixin tool lets you edit a spec by deep merging another one, in case the spec isn't under your control.

[bdazl]

Ignore my ranting, my problem is actually 'just' that of @mxinden . If I just print the error by the APIError's own error function, I get this:
unknown error (status 500): {resp:0xc0000ae3f0}

When I @mxinden 's approach to explicitly read the body of the ClientResponse I get http: read on closed response body

[deeptibaghel]

I am facing the same issue, reading the response body is a must in my application. Is there any solution available ?

[fredbi]

@deeptibaghel There is no problem reading a response body, including error responses.
You just have to define your response with a non empty schema.

Like this:

responses:
  badRequest:
    description: client error in request
    schema:
      type: object
      properties:
        errorMessage:
          type: string

If you expect a generic object, do this like:

responses:
  badRequest:
    description: client error in request
    schema:
      type: object
      additionalProperties: true

[deeptibaghel]

Thanks @fredbi , so my swagger yaml file should have it and then the client will generate methods to read it right ?

[fredbi]

Yes. You just have to insert some type assertion switch on the returned error to set it to the underlying error type and you are good to work with the content.

Something like this (example without switch and without actually using the content):

if _, notFound := erp.(*operations.GetRolesByIDRoleIDNotFound); notFound {
				// looks like this has disappeared since last fetched: skip
				continue
}

[deeptibaghel]

Many Thanks @fredbi