将对Redis实例的引用传递给Gorilla / Mux处理程序

Question

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?

Answer 1

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.