我在 Go 中構(gòu)建了一個后端 API，它可以工作，但是我想將數(shù)據(jù)庫訪問層的代碼重構(gòu)為一個函數(shù)——慣用地。// Get the form data entered by client; FirstName, LastName, phone Number,// assign the person a unique i.d// check to see if that user isn't in the database already// if they are send an error message with the a 'bad' response code// if they aren't in db add to db and send a message with successfunc CreateStudentAccountEndpoint(response http.ResponseWriter, request *http.Request){ client, err := mongo.NewClient("mongodb://localhost:27017") if err != nil { log.Fatalf("Error connecting to mongoDB client Host: Err-> %v\n ", err) } ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second) defer cancel() err = client.Connect(ctx) if err != nil { log.Fatalf("Error Connecting to MongoDB at context.WtihTimeout: Err-> %v\n ", err) } response.Header().Set("Content-Type", "application/json") studentCollection := client.Database(dbName).Collection("students") _, err = studentCollection.InsertOne(context.Background(),data) if err != nil { response.WriteHeader(501) response.Write([]byte(`{ "message": "` + err.Error() + `" }`)) } // encoding json object for returning to the client jsonStudent, err := json.Marshal(student) if err != nil { http.Error(response, err.Error(), http.StatusInternalServerError) } response.Write(jsonStudent)}我知道我可以創(chuàng)建一個返回 (*mongoClient, err) 的方法，因為我稍后會在代碼中使用客戶端局部變量。但是我不知道如何實現(xiàn)該defer cancel()部分，因為它會在方法CreateStudenAccountEndpoint結(jié)束時執(zhí)行。但是我不知道如何defer在一個方法中實現(xiàn)這個部分，該方法將識別我希望延遲發(fā)生在調(diào)用數(shù)據(jù)庫訪問層方法的函數(shù)的末尾，而不是CreateStudentAccountEndpoint實際的數(shù)據(jù)庫訪問方法本身。
1 回答
胡子哥哥
TA貢獻1825條經(jīng)驗 獲得超6個贊
據(jù)我了解，連接應該長期存在并設置為構(gòu)造函數(shù)的一部分，即不是請求流的一部分。
這通?？雌饋硐襁@樣：
type BackendAPI struct {
client *mongo.Client
}
func NewBackendAPI(mongoURI string) (*BackendAPI, error) {
client, err := mongo.NewClient(mongoURI)
if err != nil {
return nil, err
}
ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
defer cancel()
err = client.Connect(ctx)
if err != nil {
return nil, err
}
return &BackendAPI{client}, nil
}
func (api *BackendAPI) func CreateStudentAccountEndpoint(response http.ResponseWriter, request *http.Request) {
response.Header().Set("Content-Type", "application/json")
// note the use of the long-lived api.client, which is connected already.
studentCollection := api.client.Database(dbName).Collection("students")
_, err = studentCollection.InsertOne(context.Background() ,data)
if err != nil {
response.WriteHeader(501)
response.Write([]byte(`{ "message": "` + err.Error() + `" }`))
return // at this point, the method should return
}
// encoding json object for returning to the client
jsonStudent, err := json.Marshal(student)
if err != nil {
http.Error(response, err.Error(), http.StatusInternalServerError)
}
response.Write(jsonStudent)
}
如果您擔心失去連接，您可以api.client.Ping在那里實現(xiàn)對 in 的調(diào)用，但在我看來，只有當您遇到您認為可以通過重新連接恢復的故障時才應嘗試這樣做。
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