main.go

package main

import (
	"net/http"

	"github.com/gin-gonic/gin"

	"github.com/prometheus/client_golang/prometheus/promhttp"
)

// album represents data about a record album.
type album struct {
    ID     string  `json:"id"`
    Title  string  `json:"title"`
    Artist string  `json:"artist"`
    Price  float64 `json:"price"`
}

// albums slice to seed record album data.
var albums = []album{
    {ID: "1", Title: "2001", Artist: "Dr. Dre", Price: 56.99},
    {ID: "2", Title: "Rumours", Artist: "Fleetwood Mac", Price: 67.99},
    {ID: "3", Title: "Dark side of the Moon", Artist: "Pink Floyd", Price: 39.99},
    {ID: "4", Title: "Songs from the Dead", Artist: "Queens of the Stone Age", Price: 56.99},
    {ID: "5", Title: "Foo Fighters", Artist: "Foo Fighters", Price: 30.99},
}

func main() {
    router := gin.Default()
    router.GET("/ping", getStatus)
    router.GET("/metrics", gin.WrapH(promhttp.Handler()))
    router.GET("/albums", getAlbums)
    router.GET("/albums/:id", getAlbumByID)
    router.POST("/albums", postAlbums)

    err := router.Run(":8080")
    if err != nil {
        println("Unable to start router.")
        return
    }
}

func getStatus(c *gin.Context) {
    c.IndentedJSON(http.StatusOK, "pong")
}

// getAlbums responds with the list of all albums as JSON.
func getAlbums(c *gin.Context) {
    c.IndentedJSON(http.StatusOK, albums)
}

// postAlbums adds an album from JSON received in the request body.
func postAlbums(c *gin.Context) {
    var newAlbum album

    // Call BindJSON to bind the received JSON to
    // newAlbum.
    if err := c.BindJSON(&newAlbum); err != nil {
        return
    }

    // Add the new album to the slice.
    albums = append(albums, newAlbum)
    c.IndentedJSON(http.StatusCreated, newAlbum)
}

// getAlbumByID locates the album whose ID value matches the id
// parameter sent by the client, then returns that album as a response.
func getAlbumByID(c *gin.Context) {
    id := c.Param("id")

    // Loop through the list of albums, looking for
    // an album whose ID value matches the parameter.
    for _, a := range albums {
        if a.ID == id {
            c.IndentedJSON(http.StatusOK, a)
            return
        }
    }
    c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}