When I tried to setup a Go web server with GraphQL I used this as template. It is basically a combo of gin and 99designs/gqlgen.
When I create a basic gqlgen server based on net/http package, the declaration of GraphQL subscriptions work as expected.
package main
import (
"log"
"net/http"
"os"
"github.com/99designs/gqlgen/graphql/handler"
"github.com/99designs/gqlgen/graphql/playground"
"github.com/jawil003/gqlgen/graph"
"github.com/jawil003/gqlgen/graph/generated"
)
const defaultPort = "8080"
func main() {
port := os.Getenv("PORT")
if port == "" {
port = defaultPort
}
srv := handler.NewDefaultServer(generated.NewExecutableSchema(generated.Config{Resolvers: &graph.Resolver{}}))
http.Handle("/", playground.Handler("GraphQL playground", "/query"))
http.Handle("/query", srv)
log.Printf("connect to http://localhost:%s/ for GraphQL playground", port)
log.Fatal(http.ListenAndServe(":"+port, nil))
}
But when I add gin, like this:
package main
import (
"github.com/gin-gonic/gin"
"github.com/jawil003/gqlgen-todos/graph"
"github.com/jawil003/gqlgen-todos/graph/generated"
"github.com/99designs/gqlgen/graphql/handler"
"github.com/99designs/gqlgen/graphql/playground"
)
// Defining the Graphql handler
func graphqlHandler() gin.HandlerFunc {
// NewExecutableSchema and Config are in the generated.go file
// Resolver is in the resolver.go file
h := handler.NewDefaultServer(generated.NewExecutableSchema(generated.Config{Resolvers: &graph.Resolver{}}))
return func(c *gin.Context) {
h.ServeHTTP(c.Writer, c.Request)
}
}
// Defining the Playground handler
func playgroundHandler() gin.HandlerFunc {
h := playground.Handler("GraphQL", "/query")
return func(c *gin.Context) {
h.ServeHTTP(c.Writer, c.Request)
}
}
func main() {
// Setting up Gin
r := gin.Default()
r.POST("/query", graphqlHandler())
r.GET("/", playgroundHandler())
r.Run()
}
I get this issue:
{ "error": "Could not connect to websocket endpoint ws://localhost:8080/query. Please check if the endpoint url is correct." }
Is there any known solution to make gin work with graphql subscriptions?
Hello to fix error Could not connect to websocket endpoint.. with Gin change r.POST("/query", graphqlHandler()) to r.Any("/query", graphqlHandler())
Related
these is my api and i don't know what is the problem for that endpoints duplicated, i was trying if is something of config but there is not nothing about in their documentation
package main
import (
"aurora/routes"
"fmt"
"github.com/gofiber/fiber/v2"
)
func main() {
app := fiber.New(fiber.Config{
AppName: "Aurora Api V1",
})
routes.ServerRoutes(app)
app.Get("/AAAAAAAA", func(c *fiber.Ctx) error {
return c.JSON("hellow from login")
})
routesList := app.GetRoutes()
for i, route := range routesList {
fmt.Printf("%d - %d\n", i+1, route)
}
app.Listen(":3000")
}
package routes
import (
"aurora/routes/user"
"github.com/gofiber/fiber/v2"
)
func ServerRoutes(server *fiber.App) {
user.UserRoutes(server.Group("/user"))
}
package user
import "github.com/gofiber/fiber/v2"
func UserRoutes(router fiber.Router) {
router.Get("/login", func(c *fiber.Ctx) error {
return c.JSON("hellow from login")
})
router.Get("/logout", func(c *fiber.Ctx) error {
return c.JSON("hellow from logout")
})
router.Get("/signup", func(c *fiber.Ctx) error {
return c.JSON("hellow from signup")
})
}
i want that golang just map GET endpoints not HEAD endpoints, or there a reason for that?
I think HEAD method is used as default for GET routes in Fiber since it's nearly the same thing. Read more about HEAD method in MDN Docs.
I am trying to use an external (non anonymous) function in the routing of my Gin based web server as shown below:
package main
import (
"net/http"
"github.com/gin-gonic/gin"
)
func main() {
router := gin.Default()
router.GET("/hi/", Hi)
router.Run(":8080")
}
func (c *gin.Context) Hi() {
c.String(http.StatusOK, "Hello")
}
But I get 2 errors:
./main.go:13:23: undefined: Hi
./main.go:18:6: cannot define new methods on non-local type gin.Context
I am wondering how I can use anonymous functions in my endpoint handlers with gin gonic? All the documentation I've found so far uses anonymous functions.
Thanks!
You can only define a new method for a type in the same package declaring that type. That is, you cannot add a new method to gin.Context.
You should do:
func Hi(c *gin.Context) {
...
package main
import "github.com/gin-gonic/gin"
func main() {
router := gin.Default()
router.GET("/hi", hi)
var n Node
router.GET("/hello", n.hello)
router.GET("/extra", func(ctx *gin.Context) {
n.extra(ctx, "surprise~")
})
router.Run(":8080")
}
func hi(c *gin.Context) {
c.String(200, "hi")
}
type Node struct{}
func (n Node) hello(c *gin.Context) {
c.String(200, "world")
}
func (n Node) extra(c *gin.Context, data interface{}) {
c.String(200, "%v", data)
}
How do I get the body that was sent?
package main
import (
"fmt"
"github.com/gin-gonic/gin"
)
func main() {
fmt.Println("Hello, world!")
r := gin.Default()
r.POST("/", func(c *gin.Context) {
body := c.Request.Body
c.JSON(200,body);
})
r.Run(":8080");
}
I make a request via postman
{
"email": "test#gmail.com",
"password": "test"
}
and in response I get empty json {}
what to do?
You can bind the incoming request json as follows:
package main
import (
"github.com/gin-gonic/gin"
)
type LoginReq struct {
Email string
Password string
}
func main() {
r := gin.Default()
r.POST("/", func(c *gin.Context) {
var req LoginReq
c.BindJSON(&req)
c.JSON(200, req)
})
r.Run(":8080")
}
Remember this method gives 400 if there is a binding error. If you want to handle error yourself, try ShouldBindJSON which returns an error if any or nil.
This is the official prometheus golang-client example：
package main
import (
"log"
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
var cpuTemp = prometheus.NewGauge(prometheus.GaugeOpts{
Name: "cpu_temperature_celsius",
Help: "Current temperature of the CPU.",
})
func init() {
// Metrics have to be registered to be exposed:
prometheus.MustRegister(cpuTemp)
}
func main() {
cpuTemp.Set(65.3)
// The Handler function provides a default handler to expose metrics
// via an HTTP server. "/metrics" is the usual endpoint for that.
http.Handle("/metrics", promhttp.Handler())
log.Fatal(http.ListenAndServe(":8080", nil))
}
In this code, the http server uses the promhttp library.
How to modify the metrics handler when using the gin framework? I did not find answers in the documentation.
We just utilize promhttp handler.
package main
import (
"github.com/gin-gonic/gin"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
)
var cpuTemp = prometheus.NewGauge(prometheus.GaugeOpts{
Name: "cpu_temperature_celsius",
Help: "Current temperature of the CPU.",
})
func init() {
prometheus.MustRegister(cpuTemp)
}
func prometheusHandler() gin.HandlerFunc {
h := promhttp.Handler()
return func(c *gin.Context) {
h.ServeHTTP(c.Writer, c.Request)
}
}
func main() {
cpuTemp.Set(65.3)
r := gin.New()
r.GET("/", func(c *gin.Context) {
c.JSON(200, "Hello world!")
})
r.GET("/metrics", prometheusHandler())
r.Run()
}
Or we always can switch to Prometheus middleware - https://github.com/zsais/go-gin-prometheus
Use gin wrapper
router.GET("/metrics", gin.WrapH(promhttp.Handler()))
I am using prometheus with other library https://github.com/Depado/ginprom:
package main
import (
"github.com/Depado/ginprom"
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Subsystem("gin"),
ginprom.Path("/metrics"),
)
r.Use(p.Instrument())
r.GET("/hello/:id", func(c *gin.Context) {})
r.GET("/world/:id", func(c *gin.Context) {})
r.Run("127.0.0.1:8080")
}
I'm trying to get my hands dirty while playing with some Gorilla/Mux and Go-Redis but I'm facing a little implementation problem here.
Essentially I have a project structured like the following:
Where redismanager.go handles the initialization of a Redis Client:
package redismanager
import (
"fmt"
"github.com/go-redis/redis"
)
func InitRedisClient() redis.Client {
client := redis.NewClient(&redis.Options{
Addr : "localhost:6379",
Password: "",
DB : 0, //default
})
pong, err := client.Ping().Result()
if( err != nil ){
fmt.Println("Cannot Initialize Redis Client ", err)
}
fmt.Println("Redis Client Successfully Initialized . . .", pong)
return *client
}
Where main.go calls redismanager.InitRedisClient and initializes mux.Handlers:
package main
import (
"github.com/gorilla/mux"
"github.com/go-redis/redis"
"net/http"
"fmt"
"log"
"encoding/json"
"io/ioutil"
"../redismanager"
"../api"
)
type RedisInstance struct {
RInstance *redis.Client
}
func main() {
//Initialize Redis Client
client := redismanager.InitRedisClient()
//Get current redis instance to get passed to different Gorilla-Mux Handlers
redisHandler := &RedisInstance{RInstance:&client}
//Initialize Router Handlers
r := mux.NewRouter()
r.HandleFunc("/todo", redisHandler.AddTodoHandler).
Methods("POST")
fmt.Println("Listening on port :8000 . . .")
// Bind to a port and pass our router in
log.Fatal(http.ListenAndServe(":8000", r))
}
Now, I can easily define and let work properly AddTodoHandler in the same file like:
func (c *RedisInstance) AddTodoHandler(w http.ResponseWriter, r *http.Request) {
. . . doSomething
}
But, to make things a bit more modular, I'm trying to move all of these RouteHandlers inside their respective files in api package. In order to make that, I need to pass a reference to redisHandler but I'm having some difficulties when trying to make that with an Handler inside api package.
For instance, If in the main I add:
r.HandleFunc("/todo/{id}", api.GetTodoHandler(&client)).
Methods("GET")
with gettodo.go
package api
import (
"net/http"
"github.com/gorilla/mux"
"fmt"
"encoding/json"
"github.com/go-redis/redis"
)
func GetTodoHandler(c *RedisInstance) func (w http.ResponseWriter, r *http.Request) {
func (w http.ResponseWriter, r *http.Request) {
. . . doSomething
}
}
It works nicely.
I'm still pretty new to Go and haven't found any cleaner solution to that even after several researches and reads.
Is my approach correct or are there any better ones?
Write a function that converts a function with the Redis instance argument to an HTTP handler:
func redisHandler(c *RedisInstance,
f func(c *RedisInstance, w http.ResponseWriter, r *http.Request)) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { f(c, w, r) })
}
Write your API handlers like this:
func AddTodoHandler(c *RedisInstance, w http.ResponseWriter, r *http.Request) {
...
}
Add to the mux like this:
r.Handler("/todo", redisHandler(client, api.AddTodoHandler)).Methods("POST")
where client is the Redis instance.
I would recommend using an App struct which initializes DB and Routes. And all Redis methods will be called inside.
e.g. type App struct{Routes *mux.Router, DB *DB_TYPE}
And which will have App.initializeRoutes method.
type App struct {
Router *mux.Router
DB *redis.NewClient
}
func (a *App) Run(addr string) {
log.Fatal(http.ListenAndServe(":8000", a.Router))
}
func (a *App) Initialize(addr, password string, db int) error {
// Connect postgres
db, err := redis.NewClient(&redis.Options{
Addr: addr,
Password: password,
DB: db,
})
if err != nil {
return err
}
// Ping to connection
err = db.Ping()
if err != nil {
return err
}
// Set db in Model
a.DB = db
a.Router = mux.NewRouter()
a.initializeRoutes()
return nil
}
func (a *App) initializeRoutes() {
a.Router.HandleFunc("/todo", a.AddTodoHandler).Methods("POST")
a.Router.HandleFunc("/todo/{id}", a.GetTodoHandler).Methods("GET")
}
// AddTodoHandler has access to DB, in your case Redis
// you can replace the steps for Redis.
func (a *App) AddTodoHandler() {
//has access to DB
a.DB
}
Hope you get the point, you can even extract out the Model work into a separate Struct and then pass it inside func's
r.HandleFunc("/todo/{id}", redisHandler.api.GetTodoHandler).Methods("GET")
Your redisHandler, as defined in main, has no api field, so this naturally doesn't compile.
If you re-defined your RedisInstance type in the api package, and you defined the handler methods on that type in the method-specific files, then you can initialize your redisHandler using that api.RedisInstance type and you can delete the main.RedisInstance type definition:
package main
import (
"github.com/gorilla/mux"
"github.com/go-redis/redis"
"net/http"
"fmt"
"log"
"encoding/json"
"io/ioutil"
"../redismanager"
"../api"
)
func main() {
//Initialize Redis Client
client := redismanager.InitRedisClient()
//Get current redis instance to get passed to different Gorilla-Mux Handlers
redisHandler := &api.RedisInstance{RInstance:&client}
//Initialize Router Handlers
r := mux.NewRouter()
r.HandleFunc("/todo", redisHandler.AddTodoHandler).Methods("POST")
r.HandleFunc("/todo/{id}", redisHandler.GetTodoHandler).Methods("GET")
fmt.Println("Listening on port :8000 . . .")
// Bind to a port and pass our router in
log.Fatal(http.ListenAndServe(":8000", r))
}