Quickstart: Get image insights using the Bing Visual Search REST API and Go

Use this quickstart to make your first call to the Bing Visual Search API using the Go programming language. A POST request uploads an image to the API endpoint. The results include URLs and descriptive information about images similar to the uploaded image.

Prerequisites

  • Install the Go binaries.
  • Install the go-spew deep pretty printer, which is used to display results. To install go-spew, use the $ go get -u https://github.com/davecgh/go-spew command.

Project and libraries

Create a Go project in your IDE or editor. Then, import net/http for requests, ioutil to read the response, and encoding/json to handle the JSON text of results. Use the go-spew library to parse JSON results.

package main

import (
	"bytes"
	"io"
	"fmt"
	"io/ioutil"
	"mime/multipart"
	"net/http"
	"os"
	"path/filepath"
	"encoding/json"
    "github.com/davecgh/go-spew/spew"
)

Struct to format results

The BingAnswer structure formats data returned in the JSON response, which is multilevel and complex. The following implementation covers some of the essentials:

type BingAnswer struct {
	Type         string `json:"_type"`
	Instrumentation struct {
		Type string   `json:"_type"`
		PingUrlBase   string  `json:"_pingUrlBase"`
		PageLoadPingUrl  string `json:"_pageLoadPingUrl"`
	} `json:"instrumentation"`
	Tags []struct  {
	    DisplayName       string    `json:"displayName"`
		Actions                 []struct {
		    Type      string `json:"_type"`
			ActionType    string    `json:"actionType"`
			Data             struct {
			    Value     []struct {
				    WebSearchUrl          string `json:"webSearchUrl"`
				    Name        string  `json:"name"`
				}`json:"value"`
				ImageInsightsToken string `json:"imageInsightsToken"`
				InsightsMetadata struct {
				    PagesIncludingCount int `json:"pagesIncludingCount"`
					AvailableSizesCount  int  `json:"availableSizesCount"`
				}
				ImageId string  `json:"imageId"`
				AccentColor  string `json:"accentColor"`
		    } `json:"data"`
		} `json:"actions"`
	} `json:"tags"`
	Image struct {
	    WebSearchUrl   string  `json:"webSearchUrl"`
		WebSearchUrlPingSuffix  string `json:"webSearchUrlPingSuffix"`
		Name   string   `json:"name"`
		IsFamilyFriendly   bool  `json:"isFamilyFriendly"`
		ContentSize   string   `json:"contentSize"`
		EncodingFormat    string   `json:"encodingFormat"`
		HostPageDisplayUrl   string    `json:"hostPageDisplayUrl"`
		Width     int   `json:"width"`
		Height    int    `json:"height"`
		Thumbnail    struct  {
		    Width   int   `json:"width"`
			Height  int   `json:"height"`
		}
		InsightsMetadata  struct {
		    PagesIncludingCount   int   `json:"pagesIncludingCount"`
			AvailableSizesCount    int    `json:"availableSizesCount"`
		}
		AccentColor   string     `json:"accentColor"`
		VisualWords   string   `json:"visualWords"`
	} `json:"image"`
}

Main function and variables

The following code declares the main function and assigns the required variables:

  1. Confirm that the endpoint is correct and replace the token value with a valid subscription key from your Azure account.
  2. For batchNumber, assign a GUID, which is required for the leading and trailing boundaries of the POST data.
  3. For fileName, assign the image file to use for the POST.
func main() {
	// Verify the endpoint URI and replace the token string with a valid subscription key.se
	endpoint := "https://api.bing.microsoft.com/bing/v7.0/images/visualsearch"
	token := "YOUR-ACCESS-KEY"
	client := &http.Client{}
	batchNumber := "d7ecc447-912f-413e-961d-a83021f1775f"
	fileName := "ElectricBike.JPG"

	body, contentType := createRequestBody(fileName, batchNumber)
	
	req, err := http.NewRequest("POST", endpoint, body)
	req.Header.Add("Content-Type", contentType)
	req.Header.Set("Ocp-Apim-Subscription-Key", token)
	
	resp, err := client.Do(req)
	if err != nil {
		panic(err)
	}
	
       defer resp.Body.Close()
	
	resbody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		panic(err)
	}

	//fmt.Print(string(resbody))
	
	// Create a new answer.  
    ans := new(BingAnswer)
    err = json.Unmarshal(resbody, &ans)
    if err != nil {
        fmt.Println(err)
    }
	
	fmt.Print("Output of BingAnswer: \r\n\r\n")
	
	// Iterate over search results and print the result name and URL.
    for _, result := range ans.Tags {
	    spew.Dump(result)
    }
}

Boundaries of POST body

A POST request to the Visual Search endpoint requires leading and trailing boundaries to enclose the POST data. These functions aren't included in the main() block.

The leading boundary includes a batch number, the content type identifier Content-Disposition: form-data; name="image"; filename=, and the filename of the image to POST.

The trailing boundary includes the batch number only.

func BuildFormDataStart(batNum string, fileName string) string{

	startBoundary := "--batch_" + batNum + "\r\n"
	requestBoundary := startBoundary + "\r\n" + "Content-Disposition: form-data; name=\"image\"; filename=" + fileName + "\r\n\r\n"
	return requestBoundary
}

func BuildFormDataEnd(batNum string) string{

	return "\r\n" + "\r\n" + "--batch_" + batNum + "\r\n"

}

Add image bytes to POST body

The following code creates the POST request that contains image data:

func createRequestBody(fileName string, batchNumber string) (*bytes.Buffer, string) {
    file, err := os.Open(fileName)
	if err != nil {
		panic(err)
	}
	defer file.Close()

	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)
	
	writer.SetBoundary(BuildFormDataStart(batchNumber, fileName))
	
	part, err := writer.CreateFormFile("image", filepath.Base(file.Name()))
	if err != nil {
		panic(err)
	}
	io.Copy(part, file)
	writer.WriteField("lastpart", BuildFormDataEnd(batchNumber))	
	writer.Close()
    return body, writer.FormDataContentType()
}

Send the request

The following code sends the request and reads the results:

resp, err := client.Do(req)
	if err != nil {
		panic(err)
	}
	
       defer resp.Body.Close()
	
	resbody, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		panic(err)
	}

Handle the response

The Unmarshall function extracts information from the JSON text returned by the Visual Search API. The go-spew pretty printer displays the results.

	// Create a new answer.  
    ans := new(BingAnswer)
    err = json.Unmarshal(resbody, &ans)
    if err != nil {
        fmt.Println(err)
    }
	
	fmt.Print("Output of BingAnswer: \r\n\r\n")
	
	// Iterate over search results and print the result name and URL.
    for _, result := range ans.Tags {
	    spew.Dump(result)
    }

Note

Francesco Giordano contributed code to this example.

Results

The results identify images similar to the image contained in the POST body. The useful fields are WebSearchUrl and Name.

    Value: ([]struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) (len=66 cap=94) {
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=B9E6621161769D578A9E4DD9FD742128DE65225A&simid=608046863828453626",
      Name: (string) (len=87) "26\"Foldable Electric Mountain Bike Bicycle Ebike W/Lithium Battery 250W 36V MY8L | eBay"
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=5554757348A9E88E9EEAB74217E228689E716B61&simid=607988237543409883",
      Name: (string) (len=96) "Best 25+ Electric mountain bike ideas on Pinterest | Mountain bicycle, Mtb mountain bike and ..."
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=B56F626A4803D829FE326842E2B97CE5B87F17F2&simid=607991699288949513",
      Name: (string) (len=100) "Electric Fat Bike Mountain Bicycle Snow Bike Cruiser Ebike Motor Lithium Battery Dual Oil Brakes ..."
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=CCAE400EE510DCA6F5740ABAF08A5310B4EF0698&simid=608003854048890458",
      Name: (string) (len=81) "Best Mountain Bikes Under 1500 (Outstanding Performance) | Mountain Bicycle World"
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=1244730E2E3F2D5DFBED9A9CFE1DBE27B09F08BC&simid=608005181199745622",
      Name: (string) (len=98) "ANCHEER Folding Electric Mountain Bike with 26\" Super Lightweight Magnesium (36V 250W) - GearScoot"
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=38AAD876E57BB0D502FBDD5B1CB29EB7EB8DD9E2&simid=608041654062220328",
      Name: (string) (len=97) "29 best CB Bikes Gadgets & Accessories images on Pinterest | Bicycles, Bicycling and Bike gadgets"
     },
     (struct { WebSearchUrl string "json:\"webSearchUrl\""; Name string "json:\"name\"" }) {
      WebSearchUrl: (string) (len=129) "https://www.bing.com/images/search?view=detailv2&FORM=OIIRPO&id=6892C8FD22D0E42911C99AFD8FE1FD37BD82E02C&simid=608052803759703185",
      Name: (string) (len=98) "ANCHEER Folding Electric Mountain Bike with 26\" Super Lightweight Magnesium (36V 250W) - GearScoot"
     },

Next steps

Create a Visual Search single-page web app.

  • Última atualização a