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How to interact with JSON data using SQL in Golang?

Jun 03, 2024 am 11:47 AM
sql golang

在 Golang 中通过 SQL 与 JSON 数据交互共有以下步骤:使用 json.Unmarshal 函数将 JSON 数据解析为 Go 结构体,实现 JSON 到结构体的转换。使用 database/sql 包访问和操作 SQL 数据库,执行诸如插入、查询等操作。结合上述步骤,可以在 Go 中构建基于 SQL 和 JSON 的应用,实现用户注册和登录等功能。

如何在 Golang 中使用 SQL 与 JSON 数据交互?

如何在 Golang 中使用 SQL 与 JSON 数据交互

Golang 提供了强大的库和包,使使用 SQL 与 JSON 数据交互变得轻而易举。以下是如何在 Golang 中实现 SQL 与 JSON 交互:

使用 json.Unmarshal

json.Unmarshal 函数可将 JSON 数据解析为 Golang 结构体。例如:

type User struct {
    ID      int64  `json:"id"`
    Name    string `json:"name"`
    Email   string `json:"email"`
    Created int64  `json:"created"`
}

var jsonString = `{
    "id": 1,
    "name": "John Doe",
    "email": "john@example.com",
    "created": 1587398123
}`

var user User
err := json.Unmarshal([]byte(jsonString), &user)
if err != nil {
    fmt.Println("Error:", err)
}
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使用 database/sql

database/sql 包提供了访问和操作 SQL 数据库的功能。示例如下:

import (
    "database/sql"
    "log"
)

func main() {
    db, err := sql.Open("postgres", "user:password@host:port/dbname")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    jsonValue := "{ \"name\": \"Joe\", \"age\": 30 }"

    // 从 JSON 中创建 SQL struct
    type User struct {
        Name string
        Age  int
    }
    user := User{Name: "Joe", Age: 30}

    // 将 SQL struct 转换为 JSON
    userJSON, err := json.Marshal(user)
    if err != nil {
        log.Fatal(err)
    }

    // 使用 JSONB 类型插入 JSON 值
    _, err = db.Exec("INSERT INTO users (name, age) VALUES ($1, $2)", jsonValue, user.Age)
    if err != nil {
        log.Fatal(err)
    }

    // 查询 JSON 值
    rows, err := db.Query("SELECT * FROM users")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    for rows.Next() {
        var name string
        var age int
        var jsonString string
        if err := rows.Scan(&name, &age, &jsonString); err != nil {
            log.Fatal(err)
        }

        println(name, age, jsonString)
    }
}
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实战案例:用户注册与登录

我们可以利用 Go 的 SQL 与 JSON 交互能力构建一个简单的用户注册和登录 API:

注册 API

func register(w http.ResponseWriter, r *http.Request) {
    var user User

    if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
        http.Error(w, "Invalid JSON", http.StatusBadRequest)
        return
    }

    // 将 JSON 转换为 SQL struct
    sqlUser := sqlx.Named("name", user.Name).Named("password", user.Password)

    // SQL 查询插入
    query := `INSERT INTO users (name, password) VALUES (:name, :password)`

    if _, err := db.NamedExec(query, sqlUser); err != nil {
        http.Error(w, "Could not register user", http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "User registered successfully")
}
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登录 API

func login(w http.ResponseWriter, r *http.Request) {
    var user User

    if err := json.NewDecoder(r.Body).Decode(&user); err != nil {
        http.Error(w, "Invalid JSON", http.StatusBadRequest)
        return
    }

    // SQL 查询
    query := `SELECT * FROM users WHERE name = $1 AND password = $2`

    var result User
    if err := db.Get(&result, query, user.Name, user.Password); err != nil {
        http.Error(w, "Invalid user credentials", http.StatusUnauthorized)
        return
    }

    // 将 SQL struct 转换为 JWT 令牌
    tokenString, err := createJWT(result)
    if err != nil {
        http.Error(w, "Could not create JWT", http.StatusInternalServerError)
        return
    }

    fmt.Fprintf(w, "User authenticated. Token: %s", tokenString)
}
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