{"id":12572,"date":"2025-01-13T07:29:47","date_gmt":"2025-01-13T07:29:47","guid":{"rendered":"https:\/\/myprojects.advchaweb.com\/?p=12572"},"modified":"2025-01-13T10:37:20","modified_gmt":"2025-01-13T10:37:20","slug":"golang-and-gin-restful-api","status":"publish","type":"post","link":"https:\/\/myprojects.advchaweb.com\/index.php\/2025\/01\/13\/golang-and-gin-restful-api\/","title":{"rendered":"Golang and Gin Restful API"},"content":{"rendered":"

Ref: https:\/\/santrikoding.com\/tutorial-restful-api-golang-1-membuat-project-golang<\/p>\n

Note: Make sure golang is already installed by checking with ‘go version’ on your linux terminal
\n[codesyntax lang=”bash”]<\/p>\n

satria@teddy:~$ go version\r\ngo version go1.18.3 linux\/amd64<\/pre>\n
[\/codesyntax]
\nNote: it’ll be better to use the newest go version. I already installed go version 1.23.4
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Downloads$ go version\r\ngo version go1.23.4 linux\/amd64<\/pre>\n
[\/codesyntax]<\/p>\n
Note: don’t forget to run ‘go mod tidy’ on your go project<\/p>\n
1. Create a new directory for this project named ‘go-restful-api’ then go into the directory
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects$ mkdir go-restful-api\r\nsatria@teddy:~\/Documents\/projects$ cd go-restful-api\/<\/pre>\n
[\/codesyntax]<\/p>\n
then type this to create a new module ‘advcha\/backend-api’
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects\/go-restful-api$ go mod init advcha\/backend-api\r\ngo: creating new go.mod: module advcha\/backend-api<\/pre>\n
[\/codesyntax]<\/p>\n
2. Install ‘Gin’ and the libraries. Gin is a go-based web framework
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects\/go-restful-api$ go get -u github.com\/gin-gonic\/gin\r\ngo: downloading github.com\/gin-gonic\/gin v1.10.0\r\n...\r\ngithub.com\/gin-gonic\/gin imports\r\n\tgithub.com\/gin-gonic\/gin\/binding imports\r\n\tgithub.com\/pelletier\/go-toml\/v2 imports\r\n\tslices: package slices is not in GOROOT (\/usr\/local\/go\/src\/slices)<\/pre>\n
[\/codesyntax]<\/p>\n
3. Create a ‘Hello World’ with Gin
\ncreate a new file ‘main.go’ then here is the content
\n[codesyntax lang=”text”]<\/p>\n
package main\r\n\r\nimport (\r\n\t\"github.com\/gin-gonic\/gin\"\r\n)\r\n\r\nfunc main() {\r\n\t\/\/ initialize Gin\r\n\trouter := gin.Default()\r\n\r\n\t\/\/ create a GET route with an endpoint \"\/\"\r\n\trouter.GET(\"\/\", func(c *gin.Context) {\r\n\t\t\/\/ return JSON response\r\n\t\tc.JSON(200, gin.H{\r\n\t\t\t\"message\": \"Hello World!\",\r\n\t\t})\r\n\t})\r\n\r\n\t\/\/ start the server with port 3000\r\n\trouter.Run(\":3000\") \/\/ listen and serve on\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
4. Run it with ‘go run main.go’
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects\/go-restful-api$ go run main.go\r\n[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.\r\n\r\n[GIN-debug] [WARNING] Running in \"debug\" mode. Switch to \"release\" mode in production.\r\n - using env:\texport GIN_MODE=release\r\n - using code:\tgin.SetMode(gin.ReleaseMode)\r\n\r\n[GIN-debug] GET    \/                         --> main.main.func1 (3 handlers)\r\n[GIN-debug] [WARNING] You trusted all proxies, this is NOT safe. We recommend you to set a value.\r\nPlease check https:\/\/pkg.go.dev\/github.com\/gin-gonic\/gin#readme-don-t-trust-all-proxies for details.\r\n[GIN-debug] Listening and serving HTTP on :3000<\/pre>\n
[\/codesyntax]<\/p>\n
5. open it on your browser with http:\/\/localhost:3000\/
\nit should print<\/p>\n
{\"message\":\"Hello World!\"}<\/pre>\n
Install GORM (Go ORM). it’s a Object Relational Mapping (ORM) for Golang
\n1. Install GORM with MySQL driver
\n[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects\/go-restful-api$ go get -u gorm.io\/gorm gorm.io\/driver\/mysql\r\ngo: downloading gorm.io\/gorm v1.25.12\r\ngo: downloading gorm.io\/driver\/mysql v1.5.7\r\ngo: downloading github.com\/go-sql-driver\/mysql v1.7.0\r\ngo: downloading github.com\/jinzhu\/now v1.1.5\r\ngo: downloading github.com\/jinzhu\/inflection v1.0.0\r\ngo: downloading github.com\/go-sql-driver\/mysql v1.8.1\r\ngo: downloading filippo.io\/edwards25519 v1.1.0\r\ngo: added filippo.io\/edwards25519 v1.1.0\r\ngo: added github.com\/go-sql-driver\/mysql v1.8.1\r\ngo: added github.com\/jinzhu\/inflection v1.0.0\r\ngo: added github.com\/jinzhu\/now v1.1.5\r\ngo: upgraded golang.org\/x\/text v0.15.0 => v0.21.0\r\ngo: added gorm.io\/driver\/mysql v1.5.7\r\ngo: added gorm.io\/gorm v1.25.12<\/pre>\n
[\/codesyntax]<\/p>\n
2. Create a new .env file to store the variables like the database name, password, etc.
\n[codesyntax lang=”text”]<\/p>\n
export DB_USERNAME=your_mysql_username\r\nexport DB_PASSWORD=your_mysql_password\r\nexport DB_HOST=127.0.0.1\r\nexport DB_PORT=3306\r\nexport DB_NAME=db_go_restful_api<\/pre>\n
[\/codesyntax]
\nNote: rename ‘your_mysql_username’ and ‘your_mysql_password’ for your mysql account
\n‘db_go_restful_api’ is the database name we will create later<\/p>\n
We need to install a package ‘github.com\/joho\/godotenv’ on the terminal ‘go get github.com\/joho\/godotenv’ to read the .env file
\nNote: run ‘go mod tidy’ to install any missing packages if exist<\/p>\n
2. Create a Post model
\ncreate a new directory ‘models’ then create a new file ‘post.go’ in it. here is the file content
\n[codesyntax lang=”text”]<\/p>\n
 <\/p>\n
package models\r\n\r\ntype Post struct {\r\n\t\/\/ ID is the unique identifier of the post\r\n\tID \tint \t`json:\"id\" gorm:\"primary_key\"`\r\n\t\/\/ Title is the title of the post\r\n\tTitle \tstring \t`json:\"title\"`\r\n\t\/\/ Content is the content of the post\r\n\tContent string \t`json:\"content\"`\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
3. create a database connection
\ncreate a new file ‘setup.go’ in the ‘models’ directory. here is the file content
\n[codesyntax lang=”text”]<\/p>\n
package models\r\n\r\nimport (\r\n\t\"fmt\"\r\n\t\"os\"\r\n\t\"gorm.io\/driver\/mysql\"\r\n\t\"gorm.io\/gorm\"\r\n)\r\n\r\nvar DB *gorm.DB\r\n\r\nfunc ConnectDatabase() {\r\n\t\/\/ create a database connection. The connection string is in the format:\r\n\tusername := os.Getenv(\"DB_USERNAME\")\r\n\tpassword := os.Getenv(\"DB_PASSWORD\")\r\n\thost := os.Getenv(\"DB_HOST\")\r\n\tport := os.Getenv(\"DB_PORT\")\r\n\tdbname := os.Getenv(\"DB_NAME\")\r\n\r\n\tdsn := fmt.Sprintf(\"%s:%s@tcp(%s:%s)\/%s?charset=utf8mb4&parseTime=True&loc=Local\",\r\n\t\tusername, password, host, port, dbname)\r\n\t\r\n\tdatabase, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})\r\n\r\n\t\/\/ check if there is an error when connecting to the database\r\n\tif err != nil {\r\n\t\tpanic(\"Failed to connect to database!\")\r\n\t}\r\n\r\n\t\/\/ if there is no error, then create a table for the 'Post' model\r\n\tdatabase.AutoMigrate(&Post{})\r\n\r\n\t\/\/ assign the database connection to the global variable 'DB'\r\n\tDB = database\r\n}\r\n\r\nfunc GetDB() *gorm.DB {\r\n\treturn DB\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
4. create a new mysql database ‘db_go_restful_api’<\/p>\n
5. Create a new Post controller ‘postController.go’ in ‘controllers’ directory
\n[codesyntax lang=”text”]<\/p>\n
package controllers\r\n\r\nimport (\r\n\t\"advcha\/backend-api\/models\"\r\n\t\"github.com\/gin-gonic\/gin\"\r\n)\r\n\r\n\/\/ get all posts\r\nfunc FindPosts(c *gin.Context) {\r\n\t\/\/ get all posts from the database\r\n\tvar posts []models.Post\r\n\tmodels.DB.Find(&posts)\r\n\r\n\t\/\/ return JSON response\r\n\tc.JSON(200, gin.H{\r\n\t\t\"status\": \"success\",\r\n\t\t\"message\": \"All posts retrieved successfully\",\r\n\t\t\"data\": posts\r\n\t})\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
6. Create a route API Post
\nedit main.go to import the models and controllers. Also put the route in it. so it’ll be like this
\n[codesyntax lang=”text”]<\/p>\n
package main\r\n\r\nimport (\r\n\t\"advcha\/backend-api\/controllers\"\r\n\t\"advcha\/backend-api\/models\"\r\n\t\"github.com\/joho\/godotenv\"\r\n\t\"github.com\/gin-gonic\/gin\"\r\n\t\"log\"\r\n)\r\n\r\nfunc main() {\r\n\t\/\/ load the .env file\r\n\terr := godotenv.Load()\r\n\tif err != nil {\r\n\t\tlog.Fatal(\"Error loading .env file\")\r\n\t}\r\n\r\n\t\/\/ initialize Gin\r\n\trouter := gin.Default()\r\n\r\n\t\/\/ connect to the database\r\n\tmodels.ConnectDatabase()\r\n\r\n\t\/\/ create a GET route with an endpoint \"\/\"\r\n\trouter.GET(\"\/\", func(c *gin.Context) {\r\n\t\t\/\/ return JSON response\r\n\t\tc.JSON(200, gin.H{\r\n\t\t\t\"message\": \"Hello World!\",\r\n\t\t})\r\n\t})\r\n\r\n\t\/\/ create a GET route with an endpoint \"\/posts\"\r\n\trouter.GET(\"\/api\/posts\", controllers.FindPosts)\r\n\r\n\t\/\/ start the server with port 3000\r\n\trouter.Run(\":3000\") \/\/ listen and serve on\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
 <\/p>\n
7. Run it and open it on your browser
\nIf everything okay, the url http:\/\/localhost:3000\/api\/posts will show<\/p>\n
{\"data\":[],\"message\":\"All posts retrieved successfully\",\"status\":\"success\"}<\/pre>\n
Note: Also we can check it via Postman
\ncreate a new collection ‘Go Gin Restful API’ then create a new GET request ‘api_posts’ with url http:\/\/localhost:3000\/api\/posts
\n\"\"<\/p>\n
Insert data into the database
\n1. Create a new function ‘InsertPost’ in postController.go
\nnote: first, we need to install a package ‘github.com\/go-playground\/validator\/v10′[codesyntax lang=”bash”]<\/p>\n
satria@teddy:~\/Documents\/projects\/go-restful-api$ go get github.com\/go-playground\/validator\/v10\r\ngo: upgraded github.com\/gabriel-vasile\/mimetype v1.4.3 => v1.4.8\r\ngo: upgraded github.com\/go-playground\/validator\/v10 v10.20.0 => v10.24.0\r\ngo: upgraded golang.org\/x\/crypto v0.23.0 => v0.32.0\r\ngo: upgraded golang.org\/x\/net v0.25.0 => v0.34.0\r\ngo: upgraded golang.org\/x\/sys v0.20.0 => v0.29.0\r\nsatria@teddy:~\/Documents\/projects\/go-restful-api$ go mod tidy<\/pre>\n
[\/codesyntax]<\/p>\n
[codesyntax lang=”text”]<\/p>\n
package controllers\r\n\r\nimport (\r\n\t\"errors\"\r\n\t\"net\/http\"\r\n\t\"advcha\/backend-api\/models\"\r\n\t\"github.com\/gin-gonic\/gin\"\r\n\t\"github.com\/go-playground\/validator\/v10\"\r\n)\r\n\r\n\/\/ ValidatePostInput struct is used to validate the input of the post\r\ntype ValidatePostInput struct {\r\n\tTitle string `json:\"title\" binding:\"required\"`\r\n\tContent string `json:\"content\" binding:\"required\"`\r\n}\r\n\r\n\/\/ ErrorMsg struct is used to return the error message\r\ntype ErrorMsg struct {\r\n\tField   string `json:\"field\"`\r\n\tMessage string `json:\"message\"`\r\n}\r\n\r\n\/\/ GetErrorMsg function is used to get the error message\r\nfunc GetErrorMsg(fe validator.FieldError) string {\r\n\tswitch fe.Tag() {\r\n\tcase \"required\":\r\n\t\treturn \"This field is required\"\r\n\t}\r\n\treturn \"Unknown error\"\r\n}\r\n\r\n\/\/ get all posts\r\nfunc FindPosts(c *gin.Context) {\r\n\t\/\/ get all posts from the database\r\n\tvar posts []models.Post\r\n\tmodels.DB.Find(&posts)\r\n\r\n\t\/\/ return JSON response\r\n\tc.JSON(200, gin.H{\r\n\t\t\"status\": \"success\",\r\n\t\t\"message\": \"All posts retrieved successfully\",\r\n\t\t\"data\": posts,\r\n\t})\r\n}\r\n\r\nfunc InsertPost(c *gin.Context) {\r\n\t\/\/ validate the input\r\n\tvar input ValidatePostInput\r\n\r\n\tif err := c.ShouldBindJSON(&input); err != nil {\r\n\t\tvar ve validator.ValidationErrors\r\n\t\tif errors.As(err, &ve) {\r\n\t\t\tout := make([]ErrorMsg, len(ve))\r\n\t\t\tfor i, fe := range ve {\r\n\t\t\t\tout[i] = ErrorMsg{fe.Field(), GetErrorMsg(fe)}\r\n\t\t\t}\r\n\t\t\tc.AbortWithStatusJSON(http.StatusBadRequest, gin.H{\"error\": out})\r\n\t\t}\r\n\t\treturn\r\n\t}\r\n\r\n\t\/\/ create a new post\r\n\tpost := models.Post{Title: input.Title, Content: input.Content}\r\n\r\n\t\/\/ insert the new post into the database\r\n\tmodels.DB.Create(&post)\r\n\r\n\t\/\/ return JSON response\r\n\tc.JSON(200, gin.H{\r\n\t\t\"status\": \"success\",\r\n\t\t\"message\": \"Post created successfully\",\r\n\t\t\"data\": post,\r\n\t})\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
2. Then add a route in main.go to insert the post like this
\n[codesyntax lang=”text”]<\/p>\n
func main() {\r\n\t...\r\n\r\n\t\/\/ create a GET route with an endpoint \"\/posts\"\r\n\trouter.GET(\"\/api\/posts\", controllers.FindPosts)\r\n\r\n\t\/\/ create a POST route with an endpoint \"\/posts\"\r\n\trouter.POST(\"\/api\/posts\", controllers.InsertPost)\r\n\r\n\t\/\/ start the server with port 3000\r\n\trouter.Run(\":3000\") \/\/ listen and serve on\r\n}<\/pre>\n
[\/codesyntax]<\/p>\n
3. Run and test with Postman
\n\"\"<\/p>\n
Note: also need to test the validation with a json for empty title and content to make sure the validation is working.
\nthe above screen showed the json with title and content and the success result
\nthe output on http:\/\/localhost:3000\/api\/posts will be like this:<\/p>\n
{\"data\":[{\"id\":1,\"title\":\"My First Post\",\"content\":\"Here is the content of my first post\"}],\"message\":\"All posts retrieved successfully\",\"status\":\"success\"}<\/pre>\n","protected":false},"excerpt":{"rendered":"
Ref: https:\/\/santrikoding.com\/tutorial-restful-api-golang-1-membuat-project-golang Note: Make sure golang is already installed by checking with ‘go version’ on your linux terminal [codesyntax lang=”bash”] satria@teddy:~$ go version go version go1.18.3 linux\/amd64 [\/codesyntax] Note: it’ll be better to use the newest go version. I already installed go version 1.23.4 [codesyntax lang=”bash”] satria@teddy:~\/Downloads$ go version go version go1.23.4 linux\/amd64 [\/codesyntax] Note: … Continue reading “Golang and Gin Restful API”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[45,128],"tags":[],"class_list":["post-12572","post","type-post","status-publish","format-standard","hentry","category-api-2","category-golang"],"_links":{"self":[{"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/posts\/12572","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/comments?post=12572"}],"version-history":[{"count":18,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/posts\/12572\/revisions"}],"predecessor-version":[{"id":12593,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/posts\/12572\/revisions\/12593"}],"wp:attachment":[{"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/media?parent=12572"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/categories?post=12572"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/myprojects.advchaweb.com\/index.php\/wp-json\/wp\/v2\/tags?post=12572"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}