Question

我有此代码：

func GetAll(c *gin.Context) {

var veiculos model.Veiculo

rows, err := db.Query("SELECT * FROM vei_veiculo")
if err != nil {
    fmt.Println("[GetAll] erro ao abrir o query db inteiro")
}
defer rows.Close()
for rows.Next() {
    err := rows.Scan(&veiculos)
    if err != nil {
        fmt.Println("[GetAll] erro ao scanear uma linha'")
    }
}
fmt.Println(veiculos)}

我的结构名称是model.Veiculo，我想将其全部打印一次。扫描查询行时似乎出现错误。我做错了什么？

Answer 1

假设您正在使用database/sql，则函数签名为func (rs *Rows) Scan(dest ...interface{}) error。

您需要对结构的每个成员进行扫描，类似于：

err := rows.Scan(&veiculos.ID, &veiculos.Name, &veiculos.Description)

Answer 2

要将每一行扫描到自己的结构，我建议采用类似的方法：

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
)

type Person struct {
    FirstName string
    LastName  string
    Email     string
}

func main() {
    db, err := sql.Open("mysql", "dsn...")
    if err != nil {
        log.Fatalln(err)
    }
    defer db.Close()

    people := []Person{}

    rows, err := db.Query("SELECT * FROM people")
    if err != nil {
        log.Fatalln(err)
    }

    for rows.Next() {
        person := Person{}
        if err := rows.Scan(&person.FirstName, &person.LastName, &person.Email); err != nil {
            log.Fatalln(err)
        }
        people = append(people, person)
    }

    fmt.Printf("%+v\n", people)
}

或者，https://github.com/jmoiron/sqlx库作为将SQL查询数据编组到结构的解决方案之一而存在。我个人更喜欢这种方法，因为它的行为更像是Unmarshal函数：

package main

import (
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
    "github.com/jmoiron/sqlx"
)

type Person struct {
    FirstName string `db:"first_name"`
    LastName  string `db:"last_name"`
    Email     string `db:"email"`
}

func main() {
    db, err := sqlx.Connect("mysql", "dsn...")
    if err != nil {
        log.Fatalln(err)
    }

    people := []Person{}

    if err := db.Select(&people, "SELECT * FROM people"); err != nil {
        log.Fataln(err)
    }

    fmt.Printf("%+v\n", people)
}

采用以下两种方法之一，即可轻松使用json.Marshal people变量和中提琴的方法！

祝你好运！

如何查询倍数行并解析为json？

2 个答案: