我正在嘗試運行這個簡單的查詢來回傳 id，根據作者的說法，我們使用 QueryRow 函式，好的，但是這個查詢結果回傳了一個期望 2 個 args 但在這里某處收到 3 個錯誤。
查詢模型.go
type WidgetetModel struct {
DB *pgxpool.Pool
}
func (m *WidgetModel) Insert(title, content, expires string) (int, error) {
stmt := `INSERT INTO widgets (title, content, created, expires) VALUES($1, $2, NOW(), NOW() INTERVAL '$3 day') RETURNING id;`
var id int
err := m.DB.QueryRow(context.Background(), stmt, title, content, expires).Scan(&id)
if err != nil {
if errors.Is(err, sql.ErrNoRows) {
return 0, models.ErrNoRecord
} else {
return 0, err
}
}
return 0, nil
}
處理程式.go
func (app *application) createWidget(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
w.Header().Set("Allow", http.MethodPost)
app.clientError(w, http.StatusMethodNotAllowed) // Use the clientError() helper.
return
}
title := "Widget 1"
content := "Some content here..."
expires := "7"
id, err := app.widgets.Insert(title, content, expires)
if err != nil {
app.serverError(w, err) <-- line 57
return
}
http.Redirect(w, r, fmt.Sprintf("/widget?id=%v", id), http.StatusSeeOther)
}
main.go
我只是在這里使用一個結構來為我的處理程式注入依賴項。
dbPool, err := openDB(*dsn)
if err != nil {
errorLog.Fatal(err)
}
defer dbPool.Close()
app := &application{
errorLog: errorLog,
infoLog: infoLog,
snippets: &postgresql.WidgetModel{DB: dbPool},
}
///
func openDB(dsn string) (*pgxpool.Pool, error) {
pool, err := pgxpool.Connect(context.Background(), dsn)
if err != nil {
return nil, err
}
if err = pool.Ping(context.Background()); err != nil {
return nil, err
}
return pool, nil
}
錯誤輸出
go run ./cmd/web
INFO 2022/02/20 17:19:30 Starting server on :4000
ERROR 2022/02/20 17:19:38 handlers.go:57: expected 2 arguments, got 3
goroutine 34 [running]:
runtime/debug.Stack()
/usr/local/go/src/runtime/debug/stack.go:24 0x88
main.(*application).serverError(0x1400008e000, {0x1005c7be8, 0x1400009a1c0}, {0x1005bf2c0, 0x14000094120})
/Users/spencerlong/Desktop/Golang/Snippetts/cmd/web/helpers.go:12 0x44
main.(*application).createSnippet(0x1400008e000, {0x1005c7be8, 0x1400009a1c0}, 0x140000c8000)
/Users/spencerlong/Desktop/Golang/Snippetts/cmd/web/handlers.go:57 0x200
net/http.HandlerFunc.ServeHTTP(0x14000094020, {0x1005c7be8, 0x1400009a1c0}, 0x140000c8000)
/usr/local/go/src/net/http/server.go:2046 0x40
net/http.(*ServeMux).ServeHTTP(0x14000092000, {0x1005c7be8, 0x1400009a1c0}, 0x140000c8000)
/usr/local/go/src/net/http/server.go:2424 0x18c
net/http.serverHandler.ServeHTTP({0x1400009a000}, {0x1005c7be8, 0x1400009a1c0}, 0x140000c8000)
/usr/local/go/src/net/http/server.go:2878 0x444
net/http.(*conn).serve(0x140000b0000, {0x1005ca280, 0x14000096180})
/usr/local/go/src/net/http/server.go:1929 0xb6c
created by net/http.(*Server).Serve
/usr/local/go/src/net/http/server.go:3033 0x4b8
幫手.go
func (app *application) serverError(w http.ResponseWriter, err error) {
trace := fmt.Sprintf("%s\n%s", err.Error(), debug.Stack())
app.errorLog.Output(2, trace)
http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
}
uj5u.com熱心網友回復：
從您收到的錯誤中：
expected 2 arguments, got 3
我懷疑$3在 SQL 引號內的查詢中不會被解釋為引數。另外據我所知，這不是在 postgres 中使用引數間隔的正確方法。正確的方法是寫interval '1 day' * $1
所以我認為如果您將代碼更改為：
stmt := `INSERT INTO widgets (title, content, created, expires) VALUES($1, $2, NOW(), NOW() INTERVAL '1 day' * $3) RETURNING id;`
它會起作用的。但請確保將expires引數更改為 int 型別。
uj5u.com熱心網友回復：
'$3 day'
您不能將查詢引數作為字串文字的一部分傳遞。
嘗試將所有INTERVAL '$3 day'部分替換為引數。像這個。
func (m *WidgetModel) Insert(title, content, expires string) (int, error) {
stmt := `
INSERT INTO widgets (title, content, created, expires)
VALUES ($1, $2, NOW(), NOW() $3)
RETURNING id;`
var id int
expiresDays, err := strconv.ParseInt(expires, 10, 32)
if err != nil {
return 0, err
}
expiresInterval := pgtype.Interval{
Days: int32(expiresDays),
Status: pgtype.Present}
err = m.DB.QueryRow(context.Background(), stmt, title, content,
expiresInterval).Scan(&id)
if err != nil {
if errors.Is(err, sql.ErrNoRows) {
return 0, models.ErrNoRecord
} else {
return 0, err
}
}
return 0, nil
}
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