Comment créer une liste déplaçable à l'aide de Go et React

CREATE TABLE items (
    id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(255) NOT NULL,
    position INT NOT NULL,
    PRIMARY KEY (id)
);

package main

import (
    "github.com/gin-gonic/gin"
    "github.com/jinzhu/gorm"
    _ "github.com/jinzhu/gorm/dialects/mysql"
)

type Item struct {
    ID       int    `gorm:"primary_key" json:"id"`
    Name     string `gorm:"not null" json:"name"`
    Position int    `gorm:"not null" json:"position"`
}

func main() {
    // 初始化Gin框架
    r := gin.Default()

    // 连接MySQL数据库
    db, err := gorm.Open("mysql", "{username}:{password}@/{database_name}?charset=utf8&parseTime=True&loc=Local")
    if err != nil {
        panic("无法连接到数据库")
    }
    defer db.Close()

    // 自动迁移schema
    db.AutoMigrate(&Item{})

    // 添加CORS中间件
    r.Use(corsMiddleware())

    // 定义API路由
    api := r.Group("/api")
    {
        api.GET("/items", listItems)
        api.PUT("/items/:id", updateItem)
    }

    // 启动服务
    r.Run(":8080")
}

// 列出所有项
func listItems(c *gin.Context) {
    db := c.MustGet("db").(*gorm.DB)

    var items []Item
    db.Find(&items)

    c.JSON(200, items)
}

// 更新单个项目
func updateItem(c *gin.Context) {
    db := c.MustGet("db").(*gorm.DB)

    // 从URL参数获得项目的ID
    id := c.Param("id")

    // 从请求体得到项目的其他项（名称和位置）
    var input Item
    if err := c.BindJSON(&input); err != nil {
        c.JSON(400, gin.H{"error": err.Error()})
        return
    }

    // 更新数据库
    var item Item
    if db.First(&item, id).RecordNotFound() {
        c.JSON(404, gin.H{"error": "项目未找到"})
        return
    }

    item.Name = input.Name
    item.Position = input.Position

    if err := db.Save(&item).Error; err != nil {
        c.JSON(400, gin.H{"error": "更新项目失败"})
        return
    }

    c.JSON(200, item)
}

// 添加CORS中间件
func corsMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        c.Writer.Header().Set("Access-Control-Allow-Origin", "*")
        c.Writer.Header().Set("Access-Control-Allow-Methods", "GET, PUT, POST, DELETE, OPTIONS")
        c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type")
        c.Writer.Header().Set("Access-Control-Max-Age", "86400")
        if c.Request.Method == "OPTIONS" {
            c.AbortWithStatus(200)
            return
        }
        c.Next()
    }
}

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import { DragDropContext, Droppable, Draggable } from 'react-beautiful-dnd';

export default function ItemList() {
    const [items, setItems] = useState([]);

    useEffect(() => {
        axios.get('http://localhost:8080/api/items').then((response) => {
            setItems(response.data);
        });
    }, []);

    function onDragEnd(result) {
        const { destination, source, draggableId } = result;
        if (!destination) {
            return;
        }
        if (
            destination.droppableId === source.droppableId &&
            destination.index === source.index
        ) {
            return;
        }

        const item = items.find((i) => i.id === parseInt(draggableId));
        const newItems = [...items];
        newItems.splice(source.index, 1);
        newItems.splice(destination.index, 0, item);

        axios
            .put(`http://localhost:8080/api/items/${draggableId}`, {
                name: item.name,
                position: destination.index,
            })
            .then(() => {
                setItems(newItems);
            });
    }

    return (
        <DragDropContext onDragEnd={onDragEnd}>
            <Droppable droppableId="itemList">
                {(provided) => (
                    <ul
                        {...provided.droppableProps}
                        ref={provided.innerRef}
                        className="item-list"
                    >
                        {items.map((item, index) => {
                            return (
                                <Draggable
                                    key={item.id}
                                    draggableId={item.id.toString()}
                                    index={index}
                                >
                                    {(provided) => (
                                        <li
                                            {...provided.draggableProps}
                                            {...provided.dragHandleProps}
                                            ref={provided.innerRef}
                                            className="item"
                                        >
                                            {item.name}
                                        </li>
                                    )}
                                </Draggable>
                            );
                        })}
                        {provided.placeholder}
                    </ul>
                )}
            </Droppable>
        </DragDropContext>
    );
}