如何从 Go 中解释 PostgreSQL 错误消息？

Question

我如何解析 SQL 约束错误，特别是由 Go 中的 UNIQUE、FOREIGN KEY、NOT NULL、ON DELETE RESTRICT 等约束引起的错误？

例如插入一个可能具有相同电子邮件的新用户，该电子邮件在数据库中定义为 UNIQUE 字段。 Go 中解析约束错误，return 浏览器客户端错误。

Answer 1

有关如何解释来自 github.com/lib/pq 的错误的信息，请参阅 http://godoc.org/github.com/lib/pq#Error.

这是我的做法：

// ShowError sends an appropriate error message.
func ShowError(w http.ResponseWriter, r *http.Request, err error) {
    switch e := err.(type) {
    case *pq.Error:
        switch e.Code {
        case "23502":
            // not-null constraint violation
            http.Error(w, fmt.Sprint("Some required data was left out:\n\n", e.Message), http.StatusForbidden)
            return

        case "23503":
            // foreign key violation
            switch r.Method {
            case "DELETE":
                http.Error(w, fmt.Sprint("This record can’t be deleted because another record refers to it:\n\n", e.Detail), http.StatusForbidden)
                return
            }

        case "23505":
            // unique constraint violation
            http.Error(w, fmt.Sprint("This record contains duplicated data that conflicts with what is already in the database:\n\n", e.Detail), http.StatusForbidden)
            return

        case "23514":
            // check constraint violation
            http.Error(w, fmt.Sprint("This record contains inconsistent or out-of-range data:\n\n", e.Message), http.StatusForbidden)
            return

        default:
            msg := e.Message
            if d := e.Detail; d != "" {
                msg += "\n\n" + d
            }
            if h := e.Hint; h != "" {
                msg += "\n\n" + h
            }
            http.Error(w, msg, http.StatusInternalServerError)
            return
        }

    case *strconv.NumError:
        http.Error(w, fmt.Sprintf(`"%s" is not a valid number.`, e.Num), http.StatusBadRequest)
        return

    default:
        switch err {
        case sql.ErrNoRows:
            http.NotFound(w, r)
            return
        }
    }

    http.Error(w, err.Error(), http.StatusInternalServerError)
}

如何从 Go 中解释 PostgreSQL 错误消息？

How do I interpret PostgreSQL error messages from within Go?

sql

postgresql

constraints

go