The ML engine library does not work.

[Mistobaan]

I have to manually patch the library to make it work:

diff --git a/ml/v1/ml.go b/ml/v1/ml.go
index 30573fa..498edb1 100644
--- a/ml/v1/ml.go
+++ b/ml/v1/ml.go
@@ -14,15 +14,16 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	context "golang.org/x/net/context"
-	ctxhttp "golang.org/x/net/context/ctxhttp"
-	gensupport "google.golang.org/api/gensupport"
-	googleapi "google.golang.org/api/googleapi"
 	"io"
 	"net/http"
 	"net/url"
 	"strconv"
 	"strings"
+
+	context "golang.org/x/net/context"
+	ctxhttp "golang.org/x/net/context/ctxhttp"
+	gensupport "google.golang.org/api/gensupport"
+	googleapi "google.golang.org/api/googleapi"
 )
 
 // Always reference these packages, just in case the auto-generated code
@@ -2731,15 +2732,21 @@ func (c *ProjectsPredictCall) doRequest(alt string) (*http.Response, error) {
 	}
 	reqHeaders.Set("User-Agent", c.s.userAgent())
 	var body io.Reader = nil
-	body, err := googleapi.WithoutDataWrapper.JSONReader(c.googlecloudmlv1__predictrequest)
-	if err != nil {
-		return nil, err
-	}
+	// body, err := googleapi.WithoutDataWrapper.JSONReader(c.googlecloudmlv1__predictrequest)
+	// if err != nil {
+	// 	return nil, err
+	// }
+	body = strings.NewReader(c.googlecloudmlv1__predictrequest.HttpBody.Data)
+
 	reqHeaders.Set("Content-Type", "application/json")
 	c.urlParams_.Set("alt", alt)
 	urls := googleapi.ResolveRelative(c.s.BasePath, "v1/{+name}:predict")
 	urls += "?" + c.urlParams_.Encode()
-	req, _ := http.NewRequest("POST", urls, body)
+	req, err := http.NewRequest("POST", urls, body)
+	if err != nil {
+		return nil, err
+	}
+
 	req.Header = reqHeaders
 	googleapi.Expand(req.URL, map[string]string{
 		"name": c.name,
@@ -2779,10 +2786,17 @@ func (c *ProjectsPredictCall) Do(opts ...googleapi.CallOption) (*GoogleApi__Http
 			HTTPStatusCode: res.StatusCode,
 		},
 	}
-	target := &ret
-	if err := json.NewDecoder(res.Body).Decode(target); err != nil {
+
+	var b bytes.Buffer
+
+	io.Copy(&b, res.Body)
+
+	if err := json.NewDecoder(bytes.NewReader(b.Bytes())).Decode(&ret); err != nil {
 		return nil, err
 	}
+
+	ret.Data = b.String()
+
 	return ret, nil
 	// {
 	//   "description": "Performs prediction on the data in the request.\n\n**** REMOVE FROM GENERATED DOCUMENTATION",

creating the request with:

func newMLRequest(image []byte) (*ml.GoogleCloudMlV1__PredictRequest, error) {

	imageStrValue := base64.StdEncoding.EncodeToString(image)

	jsonreq := request{
		Instances: []instance{
			{
				Key: "0",
				Image: imageb64{
					B64: imageStrValue,
				},
			},
		},
	}

	payload, err := json.Marshal(&jsonreq)
	if err != nil {
		return nil, errors.Wrap(err, "mkreq could not marshal JSON")
	}

	body := &ml.GoogleApi__HttpBody{
		Data: string(payload),
	}

	req := ml.GoogleCloudMlV1__PredictRequest{
		HttpBody: body,
	}

	req.HttpBody.ContentType = "application/json"

	return &req, nil
}

and calling the service with:

	req, err := newMLRequest(image)
	if err != nil {
		return nil, nil, errors.Wrap(err, "newMLRequest")
	}

	mlPredictCall := s.ml.Projects.Predict(s.endpoint, req)

	r, err := mlPredictCall.Context(ctx).Do()
	if err != nil {
		return nil, nil, errors.Wrap(err, "ml.predict")
	}

	var msg PredictionResponse

	log.Printf("%#v", r.Data)

	if err := json.NewDecoder(strings.NewReader(r.Data)).Decode(&msg); err != nil {
		if _, ok := err.(*json.SyntaxError); ok {
			return nil, nil, errors.Wrap(err, "ml.predict returned an unexpected json")
		}
	}

	if len(msg.Predictions) == 0 {
		return
	}

[carlosrgomes]

Hi @Mistobaan , how are you? Were you able to use ML's predict api in golang? I'm trying and it always makes mistakes.

[Mistobaan]

Yes, apply that patch and is able to do the prediction correctly. Keep in mind that how you setup the input of the model is important too.

[carlosrgomes]

Thanks I was able to call api predict! I did according to your path.

[fdc-christiansteck]

Thanks, this has been very helpful!
I put the library with your patches in a vendor folder in my project and can now make predictions.

Before patching the json payload got wrapped in a http body, which resulted in the following error message in the Cloud ML Engine logs:

jsonPayload: {
@type:  "type.googleapis.com/google.cloud.ml.v1.PredictionLogEntry"   
message:  "{"error": "Invalid request. The service expects the request to be a valid JSON object with a list-valued attribute called `instances`, i.e. `{\"instances\": [...]}`. The received request was:\n{\"httpBody\":{\"contentType\":\"application/json\",\"data\":\"{\"instances\": [...]}\"}}\n"}"
numInstances:  "1"   
}

[samsends]

Mistake:

Appears to be fixed @Mistobaan

[fdc-christiansteck]

Unfortunately the new version (2018-04-26) still doesn't work for me, error is the same as before.

[samsends]

@christiansteck Sorry, I was using a vendored version by mistake. I published this patch to GitHub as a temporary fix. Hopefully it works for you.

import  "github.com/tensortask/go-ml-engine/v1"

[destagia]

I have the same problem. How is the progress and when will this be fixed?

[jba]

We're actively working on this. Sorry, no ETA yet.

[christianwiese]

We are also desperately waiting for a solution here. Especially, since with go1.11 modules we can not vendor our own patch anymore and do not really want to create a separate fork for this.

[jeanbza]

This is on my radar, but we're dealing with several high priority issues at the moment. I'm hoping to return to this soon.

[christianwiese]

Works like a charm 🎉. Thanks for your effort.