Context

Context adalah salah satu konkuresi pattern yang bertujuan untuk mengcancel jika menemui sebuah routine yang waktu eksekusinya lama. Karena operasi yang berjalan lama memang seharusnya diberi deadline. Jalan untuk meng-handle pembatalan adalah dengan melempar context.Context to fungsi yang mengetahui proses untuk mengecek pembatalan terminasi dini.

• Tambahkan argumen context.Context ke semua fungsi di models/user.go

• Passing ctx variable ke db.QueryContext, db.QueryRowContext, db.PrepareContext and stmt.ExecContext di file models/user.go

package models

import (
    "context"
    "database/sql"
    "essentials/libraries/api"
)

// User : struct of User
type User struct {
    ID       uint64
    Username string
    Password string
    Email    string
    IsActive bool
}

// List of users
func (u *User) List(ctx context.Context, db *sql.DB) ([]User, error) {
    var list []User
    const q = `SELECT id, username, password, email, is_active FROM users`

    rows, err := db.QueryContext(ctx, q)
    if err != nil {
        return list, err
    }

    defer rows.Close()

    for rows.Next() {
        var user User
        if err := rows.Scan(&user.ID, &user.Username, &user.Password, &user.Email, &user.IsActive); err != nil {
            return list, err
        }
        list = append(list, user)
    }

    return list, rows.Err()
}

// Create new user
func (u *User) Create(ctx context.Context, db *sql.DB) error {
    const query = `
        INSERT INTO users (username, password, email, is_active, created, updated)
        VALUES (?, ?, ?, 0, NOW(), NOW())
    `
    stmt, err := db.PrepareContext(ctx, query)

    if err != nil {
        return err
    }

    defer stmt.Close()

    res, err := stmt.ExecContext(ctx, u.Username, u.Password, u.Email)
    if err != nil {
        return err
    }

    id, err := res.LastInsertId()
    if err != nil {
        return err
    }

    u.ID = uint64(id)

    return nil
}

// Get user by id
func (u *User) Get(ctx context.Context, db *sql.DB) error {
    const q string = `SELECT id, username, password, email, is_active FROM users`
    err := db.QueryRowContext(ctx, q+" WHERE id=?", u.ID).Scan(&u.ID, &u.Username, &u.Password, &u.Email, &u.IsActive)

    if err == sql.ErrNoRows {
        err = api.ErrNotFound(err, "")
    }

    return err
}

// Update user by id
func (u *User) Update(ctx context.Context, db *sql.DB) error {
    const q string = `UPDATE users SET is_active = ? WHERE id = ?`
    stmt, err := db.PrepareContext(ctx, q)
    if err != nil {
        return err
    }

    defer stmt.Close()

    _, err = stmt.ExecContext(ctx, u.IsActive, u.ID)
    return err
}

// Delete user by id
func (u *User) Delete(ctx context.Context, db *sql.DB) error {
    const q string = `DELETE FROM users WHERE id = ?`
    stmt, err := db.PrepareContext(ctx, q)
    if err != nil {
        return err
    }

    defer stmt.Close()

    _, err = stmt.ExecContext(ctx, u.ID)
    return err
}

• Pass nilai dari r.Context() dari file controllers/users.go pada setiap kali memanggil method di models/user.go

package controllers

import (
    "database/sql"
    "essentials/libraries/api"
    "essentials/models"
    "essentials/payloads/request"
    "essentials/payloads/response"
    "essentials/usecases"
    "log"
    "net/http"
    "strconv"

    "github.com/julienschmidt/httprouter"
)

// Users : struct for set Users Dependency Injection
type Users struct {
    Db  *sql.DB
    Log *log.Logger
}

// List : http handler for returning list of users
func (u *Users) List(w http.ResponseWriter, r *http.Request) {
    user := new(models.User)
    list, err := user.List(r.Context(), u.Db)
    if err != nil {
        u.Log.Println("get user list", err)
        api.ResponseError(w, err)
        return
    }

    var respList []response.UserResponse
    for _, l := range list {
        var resp response.UserResponse
        resp.Transform(&l)
        respList = append(respList, resp)
    }

    api.ResponseOK(w, respList, http.StatusOK)
}

// Create new user
func (u *Users) Create(w http.ResponseWriter, r *http.Request) {

    uc := usecases.UserUsecase{Log: u.Log, Db: u.Db}
    resp, err := uc.Create(r)
    if err != nil {
        api.ResponseError(w, err)
        return
    }

    api.ResponseOK(w, resp, http.StatusCreated)
}

// View user by id
func (u *Users) View(w http.ResponseWriter, r *http.Request) {
    paramID := r.Context().Value(api.Ctx("ps")).(httprouter.Params).ByName("id")
    id, err := strconv.Atoi(paramID)
    if err != nil {
        u.Log.Println("convert param to id", err)
        api.ResponseError(w, err)
        return
    }

    user := new(models.User)
    user.ID = uint64(id)
    err = user.Get(r.Context(), u.Db)
    if err != nil {
        u.Log.Println("Get User", err)
        api.ResponseError(w, err)
        return
    }

    resp := new(response.UserResponse)
    resp.Transform(user)
    api.ResponseOK(w, resp, http.StatusOK)
}

// Update user by id
func (u *Users) Update(w http.ResponseWriter, r *http.Request) {
    paramID := r.Context().Value(api.Ctx("ps")).(httprouter.Params).ByName("id")
    id, err := strconv.Atoi(paramID)
    if err != nil {
        u.Log.Println("convert param to id", err)
        api.ResponseError(w, err)
        return
    }

    user := new(models.User)
    user.ID = uint64(id)
    err = user.Get(r.Context(), u.Db)
    if err != nil {
        u.Log.Println("Get User", err)
        api.ResponseError(w, err)
        return
    }

    userRequest := new(request.UserRequest)
    err = api.Decode(r, &userRequest)
    if err != nil {
        u.Log.Printf("error decode user: %s", err)
        api.ResponseError(w, err)
        return
    }

    userUpdate := userRequest.Transform(user)
    err = userUpdate.Update(r.Context(), u.Db)
    if err != nil {
        u.Log.Printf("error update user: %s", err)
        api.ResponseError(w, err)
        return
    }

    resp := new(response.UserResponse)
    resp.Transform(userUpdate)
    api.ResponseOK(w, resp, http.StatusOK)
}

// Delete user by id
func (u *Users) Delete(w http.ResponseWriter, r *http.Request) {
    paramID := r.Context().Value(api.Ctx("ps")).(httprouter.Params).ByName("id")
    id, err := strconv.Atoi(paramID)
    if err != nil {
        u.Log.Println("convert param to id", err)
        api.ResponseError(w, err)
        return
    }

    user := new(models.User)
    user.ID = uint64(id)
    err = user.Get(r.Context(), u.Db)
    if err != nil {
        u.Log.Println("Get User", err)
        api.ResponseError(w, err)
        return
    }

    err = user.Delete(r.Context(), u.Db)
    if err != nil {
        u.Log.Println("Delete User", err)
        api.ResponseError(w, err)
        return
    }
    api.ResponseOK(w, nil, http.StatusNoContent)
}

• Pass nilai dari r.Context() dari file usecases/user_usecase.go pada setiap kali memanggil method di models/user.go

package usecases

import (
    "database/sql"
    "errors"
    "essentials/libraries/api"
    "essentials/payloads/request"
    "essentials/payloads/response"
    "log"
    "net/http"

    "golang.org/x/crypto/bcrypt"
)

// UserUsecase struct
type UserUsecase struct {
    Log *log.Logger
    Db  *sql.DB
}

// Create new user
func (u *UserUsecase) Create(r *http.Request) (response.UserResponse, error) {
    var userRequest request.NewUserRequest
    var res response.UserResponse

    err := api.Decode(r, &userRequest)
    if err != nil {
        u.Log.Printf("error decode user: %s", err)
        return res, err
    }

    if userRequest.Password != userRequest.RePassword {
        err = api.ErrBadRequest(errors.New("Password not match"), "")
        u.Log.Printf("error : %s", err)
        return res, err
    }

    pass, err := bcrypt.GenerateFromPassword([]byte(userRequest.Password), bcrypt.DefaultCost)
    if err != nil {
        u.Log.Printf("error generate password: %s", err)
        return res, err
    }

    userRequest.Password = string(pass)

    user := userRequest.Transform()

    err = user.Create(r.Context(), u.Db)
    if err != nil {
        u.Log.Printf("error call create user: %s", err)
        return res, err
    }

    res.Transform(user)
    return res, nil
}

• Pada unit test, pass nilai dari context.Background() di file tests/user_tes.go setiap memanggil method di models/user.go

package tests

import (
    "context"
    "database/sql"
    "essentials/libraries/api"
    "essentials/models"
    "testing"

    _ "github.com/go-sql-driver/mysql"
    "github.com/google/go-cmp/cmp"
)

func TestUser(t *testing.T) {
    db, teardown := NewUnit(t)
    defer teardown()

    u := User{Db: db}
    t.Run("CRUD", u.Crud)
    t.Run("List", u.List)
}

// User struct for test users
type User struct {
    Db *sql.DB
}

//Crud : unit test  for create get and delete user function
func (u *User) Crud(t *testing.T) {
    ctx := context.Background()

    u0 := models.User{
        Username: "Aladin",
        Email:    "[email protected]",
        Password: "1234",
        IsActive: false,
    }

    err := u0.Create(ctx, u.Db)
    if err != nil {
        t.Fatalf("creating user u0: %s", err)
    }

    u1 := models.User{
        ID: u0.ID,
    }

    err = u1.Get(ctx, u.Db)
    if err != nil {
        t.Fatalf("getting user u1: %s", err)
    }

    if diff := cmp.Diff(u1, u0); diff != "" {
        t.Fatalf("fetched != created:\n%s", diff)
    }

    u1.IsActive = false
    err = u1.Update(ctx, u.Db)
    if err != nil {
        t.Fatalf("update user u1: %s", err)
    }

    u2 := models.User{
        ID: u1.ID,
    }

    err = u2.Get(ctx, u.Db)
    if err != nil {
        t.Fatalf("getting user u2: %s", err)
    }

    if diff := cmp.Diff(u1, u2); diff != "" {
        t.Fatalf("fetched != updated:\n%s", diff)
    }

    err = u2.Delete(ctx, u.Db)
    if err != nil {
        t.Fatalf("delete user u2: %s", err)
    }

    u3 := models.User{
        ID: u2.ID,
    }

    err = u3.Get(ctx, u.Db)

    apiErr, ok := err.(*api.Error)
    if !ok || apiErr.Err != sql.ErrNoRows {
        t.Fatalf("getting user u3: %s", err)
    }
}

//List : unit test for user list function
func (u *User) List(t *testing.T) {
    ctx := context.Background()

    u0 := models.User{
        Username: "Aladin",
        Email:    "[email protected]",
        Password: "1234",
        IsActive: false,
    }

    err := u0.Create(ctx, u.Db)
    if err != nil {
        t.Fatalf("creating user u0: %s", err)
    }

    var user models.User
    users, err := user.List(ctx, u.Db)
    if err != nil {
        t.Fatalf("listing users: %s", err)
    }
    if exp, got := 1, len(users); exp != got {
        t.Fatalf("expected users list size %v, got %v", exp, got)
    }
}

• Kita bisa mengetesnya dengan membuat time.Sleep()