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Anurag Affection
Anurag Affection

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Get API & Fetching Data from MongoDB in Go - 05

  • First check the Go version by running the command 
go version
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  • Create a folder 
mkdir <folder_name>
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  • Switch to created folder 
cd <folder_name>
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  • Initialize the go project by running the given command. You will get go.mod file. 
go mod init <folder_name>
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  • Create a main.go file, use terminal or bash 
notepad main.go touch main.go
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  • Let's write some basic code in main.go file. 
package main import ( "fmt" ) func main () { fmt.Println("Hello From Go") }
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  • Run the code by following command 
go run main.go
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  • You will see this output in console 
Hello From Go
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  • Install some packages to connect MongoDB. Here are commands 
go get go.mongodb.org/mongo-driver go get go.mongodb.org/mongo-driver/mongo
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  • Revisit the main.go file to connect MongoDB. Add some code to connect MongoDB. This is how it will look after adding. 
package main // package importing import ( "fmt" "log" "context" "go.mongodb.org/mongo-driver/mongo" "go.mongodb.org/mongo-driver/mongo/options" ) // mongodb connections var collection *mongo.Collection var ctx = context.TODO() func init() { clientOptions := options.Client().ApplyURI("mongodb://localhost:27017/") client, err := mongo.Connect(ctx, clientOptions) if err != nil { log.Fatal(err) } // check connection err = client.Ping(ctx, nil) if err != nil { log.Fatal(err) } fmt.Println("Connected to MongoDB!") collection = client.Database("testingWithGo").Collection("movies") } // entry point  func main () { fmt.Println("Hello From Go") }
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  • Run the code by following command 
go run main.go
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  • You will see this output in console 
Connected to MongoDB! Hello From Go
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  • Till, Our MongoDB is connected. Now let's add some data. We are going to add movie data. So, let's make a movie structure. 
// movie model or structure  type Movie struct { ID string `json:"id"` Title string `json:"title"` }
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  • Now write a function to add movie to database. 
// to add movie to db func addMovie(id, title string) { movie := Movie{ ID: id, Title: title, } _, err := collection.InsertOne(ctx, movie) if err != nil { log.Fatal(err) } fmt.Println("Movie added successfully!") }
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  • Call the addMovie function to main function. 
addMovie("1", "Captain America")
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  • This is how our code will look like after completing above steps 
package main // package importing import ( "fmt" "log" "context" "go.mongodb.org/mongo-driver/mongo" "go.mongodb.org/mongo-driver/mongo/options" ) // mongodb connections var collection *mongo.Collection var ctx = context.TODO() func init() { clientOptions := options.Client().ApplyURI("mongodb://localhost:27017/") client, err := mongo.Connect(ctx, clientOptions) if err != nil { log.Fatal(err) } // check connection err = client.Ping(ctx, nil) if err != nil { log.Fatal(err) } fmt.Println("Connected to MongoDB!") collection = client.Database("testingWithGo").Collection("movies") } // movie model or structure  type Movie struct { ID string `json:"id"` Title string `json:"title"` } // to add movie to db func addMovie(id, title string) { movie := Movie{ ID: id, Title: title, } _, err := collection.InsertOne(ctx, movie) if err != nil { log.Fatal(err) } fmt.Println("Movie added successfully!") } // entry point  func main () { fmt.Println("Hello From Go") // callig addMovie  addMovie("1", "Captain America") }
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  • Run the code by following command 
go run main.go
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  • You will see this output in console 
Connected to MongoDB! Hello From Go Movie added successfully!
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  • We have successfully added some data to MongoDB, you can verify in your database, which is your localhost. 
mongodb://localhost:27017/
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  • Now import these packages 
"encoding/json" "net/http" "go.mongodb.org/mongo-driver/bson"
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  • This how our import will look like 
// package importing import ( "fmt" "log" "context" "encoding/json" "net/http" "go.mongodb.org/mongo-driver/bson" "go.mongodb.org/mongo-driver/mongo" "go.mongodb.org/mongo-driver/mongo/options" )
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  • Now write a function to getAllMovies. Here is the code 
// api to get all movies func getAllMovies(w http.ResponseWriter, r *http.Request) { w.Header().Set("Content-Type", "application/json") // Define a slice to store the decoded documents var movies []Movie // Find all movies in the collection cursor, err := collection.Find(ctx, bson.M{}) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } defer cursor.Close(ctx) // Iterate through the cursor and decode each document for cursor.Next(ctx) { var movie Movie if err := cursor.Decode(&movie); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } movies = append(movies, movie) } // Check for cursor errors after iterating if err := cursor.Err(); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } // Encode the movies slice as JSON and write it to the response if err := json.NewEncoder(w).Encode(movies); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } }
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  • Call the getAllMovies with route in main, also run the server. 
 // api to getAllMovies  http.HandleFunc("/movies", getAllMovies) // our server on port on 8000 http.ListenAndServe(":8000", nil)
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  • Let's have a full code, after completing all the above steps 
package main // package importing import ( "fmt" "log" "context" "encoding/json" "net/http" "go.mongodb.org/mongo-driver/bson" "go.mongodb.org/mongo-driver/mongo" "go.mongodb.org/mongo-driver/mongo/options" ) // mongodb connections var collection *mongo.Collection var ctx = context.TODO() func init() { clientOptions := options.Client().ApplyURI("mongodb://localhost:27017/") client, err := mongo.Connect(ctx, clientOptions) if err != nil { log.Fatal(err) } // check connection err = client.Ping(ctx, nil) if err != nil { log.Fatal(err) } fmt.Println("Connected to MongoDB!") collection = client.Database("testingWithGo").Collection("movies") } // movie model or structure  type Movie struct { ID string `json:"id"` Title string `json:"title"` } // to add movie to db func addMovie(id, title string) { movie := Movie{ ID: id, Title: title, } _, err := collection.InsertOne(ctx, movie) if err != nil { log.Fatal(err) } fmt.Println("Movie added successfully!") } // api to get all movies func getAllMovies(w http.ResponseWriter, r *http.Request) { w.Header().Set("Content-Type", "application/json") // Define a slice to store the decoded documents var movies []Movie // Find all movies in the collection cursor, err := collection.Find(ctx, bson.M{}) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } defer cursor.Close(ctx) // Iterate through the cursor and decode each document for cursor.Next(ctx) { var movie Movie if err := cursor.Decode(&movie); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } movies = append(movies, movie) } // Check for cursor errors after iterating if err := cursor.Err(); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } // Encode the movies slice as JSON and write it to the response if err := json.NewEncoder(w).Encode(movies); err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } } // entry point  func main () { fmt.Println("Hello From Go") // callig addMovie  addMovie("1", "Captain America") // api to getAllMovies  http.HandleFunc("/movies", getAllMovies) // visit this url in browser fmt.Println("Your Server is running on http://localhost:8000") // our server on port on 8000 http.ListenAndServe(":8000", nil) }
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  • Run the code by following command 
go run main.go
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  • You will see this output in console 
Connected to MongoDB! Hello From Go Movie added successfully! Your Server is running on http://localhost:8000
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  • Visit http://localhost:8000/movies on browser to verify the API. This what you will get. 
[ { "id": "1", "title": "The Shawshank Redemption" }, { "id": "1", "title": "The Shawshank Redemption" }, { "id": "1", "title": "Captain America" }, { "id": "1", "title": "Captain America" }, { "id": "1", "title": "Captain America" }, { "id": "1", "title": "Captain America" } ]
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That's for this article. Thank You.

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