从golang代码将文件发送到Google Drive API会产生错误：类型为image / jpeg的内容不受支持

Question

based on the Google Drive API docs the proper way of uploading a file is:

curl -v -H 'Authorization: Bearer mytoken' -F 'metadata={"name": "test3.jpeg"};type=application/json' -F file=@jpeg_image.jpeg 'https://www.googleapis.com/upload/drive/v3/files?uploadType=multipart'

Now, I need to perform the same request from golang code, but I am having a hard time translating this to golang, here is the code I am using after several attempts:

// fileBytes are of type []byte
buffer := &bytes.Buffer{}
    multipartWriter := multipart.NewWriter(buffer)
    multipartWriter.WriteField("metadata", "{\"name\": \"test3.jpef\"};type=application/json")
    partHeader := textproto.MIMEHeader{}
    partHeader.Add("Content-Type", "image/jpeg")
    filePartWriter, _ := multipartWriter.CreatePart(partHeader)
    io.Copy(filePartWriter, bytes.NewReader(fileBytes))
    multipartWriter.Close()

    googleDriveRequest, _ := http.NewRequest(http.MethodPost, "https://www.googleapis.com/upload/drive/v3/files?uploadType=multipart", buffer)
    googleDriveRequest.Header.Add("Authorization", "Bearer "+accessToken)
    googleDriveRequest.Header.Add("Content-Type", multipartWriter.FormDataContentType())

    googleDriveAPIResponse, googleDriveAPIError := lib.HttpClient.Do(googleDriveRequest)

Using curl the request succeeds :

{
 "kind": "drive#file",
 "id": "1DwsbQGP3-QtS5p0iQqRtAjcCCsAfxzGD",
 "name": "test3.jpeg",
 "mimeType": "image/jpeg"
}

With Golang, I get a 400:

{
 \"error\": {
  \"errors\": [
   {
    \"domain\": \"global\",
    \"reason\": \"badContent\",
    \"message\": \"Unsupported content with type: image/jpeg \"
   }
  ],
  \"code\": 400,
  \"message\": \"Unsupported content with type: image/jpeg\"
 }
}

I also tried with different values for partHeader.Add("Content-Type", "image/jpeg"), I tried with application/x-www-form-urlencoded as well, I also commented out this line, and let golang do the detection, but still getting the same error.

Any suggestions or ideas?

Regards,

Answer 1

The problem is in the JSON metadata that you send. Here is a sample code (use proper error checking) that will work,

import (
    "bytes"
    "fmt"
    "io"
    "io/ioutil"
    "log"
    "mime/multipart"
    "net/http"
    "net/textproto"
)

func main() {
    accessToken := "YOUR-TOKEN"

    client := http.Client{}
    mediaData, _ := ioutil.ReadFile("test.png")

    body := &bytes.Buffer{}
    writer := multipart.NewWriter(body)

    // JSON Metadata (part-1)
    jsonMetadata := textproto.MIMEHeader{}
    metadata := `{"name": "test.png"}`
    jsonMetadata.Set("Content-Type", "application/json")
    part, _ := writer.CreatePart(jsonMetadata)
    part.Write([]byte(metadata))

    // Image bytes (part-2)
    imageData := textproto.MIMEHeader{}
    partAttach, _ := writer.CreatePart(imageData)
    io.Copy(partAttach, bytes.NewReader(mediaData))
    writer.Close()

    // Request Content Type with boundary
    contentType := fmt.Sprintf("multipart/related; boundary=%s", writer.Boundary())

    // HTTP Request with auth and content type headers
    req, _ := http.NewRequest(http.MethodPost, "https://www.googleapis.com/upload/drive/v3/files?uploadType=multipart", bytes.NewReader(body.Bytes()))
    req.Header.Add("Authorization", "Bearer "+accessToken)
    req.Header.Add("Content-Type", contentType)

    // Send request
    resp, err := client.Do(req)
    if err != nil {
        log.Fatalf("failed to send request: %v", err)
    }
    defer resp.Body.Close()
    content, _ := ioutil.ReadAll(resp.Body)

    log.Printf("http status: %d", resp.StatusCode)
    log.Printf("response: %s", string(content))
}

Reference: https://developers.google.com/drive/api/v3/manage-uploads?authuser=1#send_a_multipart_upload_request