使用 Gorilla Mux 和 CockroachDB 编写可维护 RESTful API（下）

package main
import (
  "encoding/json"
  "net/http"
  "mybook/model"
  "github.com/gorilla/mux"
  "gorm.io/gorm"
)
type Server struct {
  db *gorm.DB
}
type UpdateBook struct {
  Price       float64 `json:"price"`
  Description string  `json:"decription"`
  Category    string  `json:"category"`
}
func NewServer(db *gorm.DB) *Server {
  return &Server{db: db}
}
func (s *Server) RegisterRouter(router *mux.Router) {
  router.HandleFunc("/books", s.getBooks)
  router.HandleFunc("/book/{id}", s.getBook).Methods("GET")
  router.HandleFunc("/book", s.createBook).Methods("POST")
  router.HandleFunc("/book/{id}", s.updateBook).Methods("PUT")
  router.HandleFunc("/book/{id}", s.deleteBook).Methods("DELETE")
}
func (s *Server) getBooks(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json;charset=UTF-8")
  var books []model.Book
  if err := s.db.Find(&books).Error; err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  w.WriteHeader(http.StatusOK)
  json.NewEncoder(w).Encode(books)
}
func (s *Server) createBook(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json; charset=UTF-8")
  var book model.Book
  if err := json.NewDecoder(r.Body).Decode(&book); err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  newBook := model.Book{Price: book.Price, Description: book.Description, Category: book.Category}
  if err := s.db.Create(newBook).Error; err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  w.WriteHeader(http.StatusOK)
  json.NewEncoder(w).Encode(newBook)
}
func (s *Server) getBook(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json; charset=UTF-8")
  var book model.Book
  vars := mux.Vars(r)
  id := vars["id"]
  if err := s.db.Where("id = ?", id).First(&book).Error; err != nil {
    http.Error(w, err.Error(), http.StatusNotFound)
    return
  }
  w.WriteHeader(http.StatusOK)
  json.NewEncoder(w).Encode(book)
}
func (s *Server) updateBook(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json; charset=UTF-8")
  var updateBook UpdateBook
  var book model.Book
  vars := mux.Vars(r)
  id := vars["id"]
  if err := json.NewDecoder(r.Body).Decode(&updateBook); err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  if err := s.db.Where("id = ?", id).First(&book).Error; err != nil {
    http.Error(w, err.Error(), http.StatusNotFound)
    return
  }
  if err := s.db.Model(&book).Updates(&model.Book{
    Price:       updateBook.Price,
    Description: updateBook.Description,
    Category:    updateBook.Category}).Error; err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  w.WriteHeader(http.StatusOK)
  json.NewEncoder(w).Encode(book)
}
func (s *Server) deleteBook(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json; charset=UTF-8")
  var book model.Book
  vars := mux.Vars(r)
  id := vars["id"]
  if err := s.db.Where("id = ?", id).First(&book).Error; err != nil {
    http.Error(w, err.Error(), http.StatusNotFound)
    return
  }
  if err := s.db.Delete(&book).Error; err != nil {
    http.Error(w, err.Error(), http.StatusInternalServerError)
    return
  }
  w.WriteHeader(http.StatusOK)
  json.NewEncoder(w).Encode("Book Deleted Successfully!")
}

package main
import (
  "log"
  "net/http"
  "github.com/gorilla/mux"
  "mybook/model"
)
func main() {
  db, err := model.SetupDB()
  if err != nil {
    log.Println("Failed setting up database")
  }
  router := mux.NewRouter()
  server := NewServer(db)
  server.RegisterRouter(router)
  log.Fatal(http.ListenAndServe(":8000", router))
}