go-rel/gin-example

package handler

import (
    "errors"
    "fmt"
    "strconv"

    "github.com/gin-gonic/gin"
    "github.com/go-rel/gin-example/todos"
    "github.com/go-rel/rel"
    "github.com/go-rel/rel/where"
    "go.uber.org/zap"
)

type ctx int

const (
    loadKey string = "todosLoadKey"
)

// Todos for todos endpoints.
type Todos struct {
    repository rel.Repository
    todos      todos.Service
}

// Index handle GET /.
func (t Todos) Index(c *gin.Context) {
    var (
        result []todos.Todo
        filter = todos.Filter{
            Keyword: c.Query("keyword"),
        }
    )

    if str := c.Query("completed"); str != "" {
        completed := str == "true"
        filter.Completed = &completed
    }

    t.todos.Search(c, &result, filter)
    render(c, result, 200)
}

// Create handle POST /
func (t Todos) Create(c *gin.Context) {
    var (
        todo todos.Todo
    )

    if err := c.ShouldBindJSON(&todo); err != nil {
        logger.Warn("decode error", zap.Error(err))
        render(c, ErrBadRequest, 400)
        return
    }

    if err := t.todos.Create(c, &todo); err != nil {
        render(c, err, 422)
        return
    }

    c.Header("Location", fmt.Sprint(c.Request.RequestURI, "/", todo.ID))
    render(c, todo, 201)
}

// Show handle GET /{ID}
func (t Todos) Show(c *gin.Context) {
    var (
        todo = c.MustGet(loadKey).(todos.Todo)
    )

    render(c, todo, 200)
}

// Update handle PATCH /{ID}
func (t Todos) Update(c *gin.Context) {
    var (
        todo    = c.MustGet(loadKey).(todos.Todo)
        changes = rel.NewChangeset(&todo)
    )

    if err := c.ShouldBindJSON(&todo); err != nil {
        logger.Warn("decode error", zap.Error(err))
        render(c, ErrBadRequest, 400)
        return
    }

    if err := t.todos.Update(c, &todo, changes); err != nil {
        render(c, err, 422)
        return
    }

    render(c, todo, 200)
}

// Destroy handle DELETE /{ID}
func (t Todos) Destroy(c *gin.Context) {
    var (
        todo = c.MustGet(loadKey).(todos.Todo)
    )

    t.todos.Delete(c, &todo)
    render(c, nil, 204)
}

// Clear handle DELETE /
func (t Todos) Clear(c *gin.Context) {
    t.todos.Clear(c)
    render(c, nil, 204)
}

// Load is middleware that loads todos to context.
func (t Todos) Load(c *gin.Context) {
    var (
        id, _ = strconv.Atoi(c.Param("ID"))
        todo  todos.Todo
    )

    if err := t.repository.Find(c, &todo, where.Eq("id", id)); err != nil {
        if errors.Is(err, rel.ErrNotFound) {
            render(c, err, 404)
            c.Abort()
            return
        }
        panic(err)
    }

    c.Set(loadKey, todo)
    c.Next()
}

// Mount handlers to router group.
func (t Todos) Mount(router *gin.RouterGroup) {
    router.GET("/", t.Index)
    router.POST("/", t.Create)
    router.GET("/:ID", t.Load, t.Show)
    router.PATCH("/:ID", t.Load, t.Update)
    router.DELETE("/:ID", t.Load, t.Destroy)
    router.DELETE("/", t.Clear)
}

// NewTodos handler.
func NewTodos(repository rel.Repository, todos todos.Service) Todos {
    return Todos{
        repository: repository,
        todos:      todos,
    }
}