https://res.cloudinary.com/practicaldev/image/fetch/s--cd6Q5mqC--/c_imagga_scale,f_auto,fl_progressive,h_420,q_auto,w_1000/https://dev-to-uploads.s3.amazonaws.com/uploads/articles/hc1uaz1tvuq53qq0obl8.png
Golang image search api

Navin Kodag3 mins

09 Jun 2021

Building the REST API

I'll be using gin for this part of project.

Gin is a web framework written in Go (Golang). It features a martini-like API with performance that is up to 40 times faster thanks to httprouter. If you need performance and good productivity, you will love Gin.

TLDR

First we create our go.mod file:

 go mod init Intersect_api

Then we'll create our main.go file and add the following code.

// main.go
package main
import (
	"Intersect/server"
	"log"
	"os"
	"time"

	"github.com/getsentry/sentry-go"
)

func main() {

	// Initialize Libraries

	// Initialize and defer Sentry
	if err := sentry.Init(sentry.ClientOptions{
		Dsn: os.Getenv("SENTRY_DSN"),
	}); err != nil {
		log.Fatalln("Sentry Init Error: ", err)
	}

	defer sentry.Flush(2 * time.Second)

	// Initialize Server
	server.Init()
}
  • Create a server module and initialize the server
/// server.go
package server

import "github.com/getsentry/sentry-go"

// Init : Initialize the routes and server
func Init() {
	r := NewRouter()
	err := r.Run()

	if err != nil {
		sentry.CaptureException(err)
	}
}

  • Good rule of thumb to add some middleware with a token required
// middleware.go
package server

import (
	"net/http"

	"github.com/gin-gonic/gin"
)

func AuthMiddleware() gin.HandlerFunc {
	authHeader := "let-me-in"
	// os.Getenv("AUTHORIZATION_STRING")
	return func(c *gin.Context) {
		requiredAuth := c.Request.Header.Get("Authorization")
		if requiredAuth != authHeader {
			c.AbortWithStatusJSON(http.StatusUnauthorized, map[string]string{"message": "unauthorized peasant 😃"})
		}
		c.Next()
		// middleware
	}
}

  • Then we'll create default cors, routes and also call our middleware inside the router.use() method
package server

import (
	"Intersect/scraper"

	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
)

/// router.go
func NewRouter() *gin.Engine {
	// gin.SetMode(gin.ReleaseMode)
	router := gin.New()
	// Gin and CORS Middlewares
	router.Use(gin.Logger())
	router.Use(gin.Recovery())
	/// Cors
	router.Use(setCors())
	/// Declare Middleware
	authorized := router.Group("/")
	authorized.Use(AuthMiddleware())
	{
		authorized.GET("", scraper.Greet)
		searchRouter := authorized.Group("search")
		searchRouter.GET("", scraper.GetImgs)
	}
	return router
}

// Cors
func setCors() gin.HandlerFunc {
	return cors.New(cors.Config{
		AllowOrigins:     []string{"*"},
		AllowMethods:     []string{"GET", "OPTIONS", "PUT"},
		AllowHeaders:     []string{"Origin", "Authorization"},
		ExposeHeaders:    []string{"Content-Length"},
		AllowCredentials: true,
	})
}

Then we'll create a scraper directory/module and create two files

  • greeting.go for default route and
  • search.go for the request route. (Because the default route will be lonely).
package scraper

import (
	"net/http"

	"github.com/gin-gonic/gin"
)

func Greet(c *gin.Context) {
	c.JSON(http.StatusOK, map[string]string{"sup": "🤘🚀"})

}

package scraper

import (
	"fmt"
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/gocolly/colly"
)

func GetImgs(c *gin.Context) {
	searchQuery := c.Query("q")
	res := getSearch(searchQuery)
	c.JSON(http.StatusOK, res)
}

func getSearch(searchQuery string) Images {
	searchString := strings.Replace(searchQuery, " ", "-", -1)
	c := colly.NewCollector()
	c.UserAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X x.y; rv:42.0) Gecko/20100101 Firefox/42.0"
	c.AllowURLRevisit = true
	c.DisableCookies()
	array := []string{}

	// Find and visit all links
	c.OnHTML("img[src]", func(e *colly.HTMLElement) {
		src := e.Attr("src")
		if src != "" {
			array = append(array, e.Attr("src"))
		}
	})
	// Requesting a url for html
	c.OnRequest(func(r *colly.Request) {
		fmt.Println("Visiting", r.URL)
	})
	// search query
	pexelsQuery := strings.Replace(searchString, "-", "%20", -1)
	stocSnapQuery := strings.Replace(searchString, "-", "+", -1)
	//
	c.Visit("https://unsplash.com/s/" + searchString)
	c.Visit("https://burst.shopify.com/photos/search?utf8=%E2%9C%93&q=" + searchString + "&button=")
	c.Visit("https://www.pexels.com/search/" + pexelsQuery + "/")
	c.Visit("https://www.flickr.com/search/?text=" + pexelsQuery)
	c.Visit("http://www.google.com/images?q=" + stocSnapQuery)
	c.Visit("https://stocksnap.io/search/" + stocSnapQuery)
	//
	return Images{
		Count: len(array),
		Data:  array}
}

type Images struct {
	Count int      `json:"counts"`
	Data  []string `json:"data"`
}

After that, we'll build a binary using

go build -o /bin/Intersect_api -v .

Now that's almost all the code we'll need.

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