.Net Core Web Api_笔记25_api结合EFCore数据库操作part3_产品分类数据的编辑与删除（EF的更新写法怎么这么多种！如何观察EF产生的SQL）

我们在上一篇的Show.html
已经完成了数据查询呈现
这里要多出操作（比方像是编辑、删除…）

在Show.html
加上对应client端 jQuery访问调用程序
以及扩充操作的相关链接

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <link href="../css/bootstrap/css/bootstrap.min.css" rel="stylesheet" />
    <script src="../js/jquery/jquery.min.js"></script>
</head>
<body style="margin:20px;">
    <table id="tbProductCategory" class="table table-bordered">
        <thead>
            <tr>
                <td nowrap>產品類別ID</td>
                <td nowrap>產品類別名稱</td>
                <td nowrap>操作</td>
            </tr>
        </thead>
        <tbody>
        </tbody>
    </table>

    <script type="text/javascript">
        $(function () {
            var tbody = $('#tbProductCategory tbody');
            $.ajax({
                type: 'get',
                url: '/api/pcategory/show',
                dataType: 'json',
                success: function (result) {
                    $.each(result, function (n, value) {
                        var tr_val = "";
                        tr_val += "<tr><td>" + value.cId + "</td>" +
                            "<td>" + value.cTitle + "</td>" +
                            "<td nowrap>" +
                            "<a href='Edit.html?id=" + value.cId + "'>編輯</a> " +
                            "<a href='javascript:Del(\"" + value.cId + "\")'>刪除</a>" + //傳 GUID 當參數 要用雙引號包覆 跳脫字元(\")
                            "</td></tr>";
                        tbody += tr_val;
                    });
                    $('#tbProductCategory').append(tbody);
                }
            });
        });

        function Del(id) {
            $.ajax({
                type: "delete",
                url: "/api/pcategory/delete?id=" + id,
                dataType: "json",
                success: function (result) {
                    if (result != "0") {
                        location.href = "Show.html";
                    }
                }
            });
        }


    </script>

</body>
</html>

编辑部分传入对应产品类别ID并进行页面跳转与后续资料回填
删除则针对特定产品类别ID直接呼叫HTTP Delete即可

扩充编辑用的 Action Method

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Net5EFCoreWebApiApp.Data;
using Net5EFCoreWebApiApp.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Net5EFCoreWebApiApp.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class PCategoryController : ControllerBase
    {        
        //Startup.cs中註冊EF服務後，就可在特定控制器藉由.net core預設DI，透過建構子去實踐存取ProductDbContext。
        private readonly ProductDbContext _dbContext;
        public PCategoryController(ProductDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        [HttpPost("Add")]
        public async Task<ActionResult<int>> AddProductCategory(PCategory pCategory)
        {
            if (pCategory == null)
                return NotFound();

            if (string.IsNullOrEmpty(pCategory.CTitle))
                return NotFound();

            pCategory.CId = Guid.NewGuid();
            _dbContext.PCategories.Add(pCategory);
            int RowCount = await _dbContext.SaveChangesAsync();
            return CreatedAtAction(nameof(AddProductCategory),RowCount);
        }

        [HttpGet("Show")]
        public async Task<ActionResult<List<PCategory>>> ShowProductCategory()
        {
            var categories = await _dbContext.PCategories.ToListAsync();
            return categories;
        }

        [HttpGet("GetById")]
        public async Task<ActionResult<PCategory>> GetSpecificCategoryById(string id)
        {
            if (string.IsNullOrWhiteSpace(id))
                return NotFound();

            var category = await _dbContext.PCategories.AsNoTracking()
                .FirstOrDefaultAsync(item=>item.CId==new Guid(id));
            return category;
        }

        [HttpPut("Update")]
        public async Task<ActionResult<int>> UpdateCategory(PCategory pCategory)
        {
            if (pCategory == null)
                return NotFound();

            if (string.IsNullOrEmpty(pCategory.CTitle))
                return NotFound();

            _dbContext.Entry(pCategory).State = EntityState.Modified;
            var count = await _dbContext.SaveChangesAsync();
            return count;
        }
    }
}

Edite.html对应client端 jQuery存取呼叫程序

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title></title>    
    <link href="../css/bootstrap/css/bootstrap.min.css" rel="stylesheet" />
    <script src="../js/jquery/jquery.min.js"></script>
</head>
<body>
    <div style="padding:20px;border:1px solid #0094ff;width:600px;margin:30px;">
        <h3>產品分類編輯</h3>
        <hr />
        <div class="form-horizontal">
            <div class="form-group col-4">
                <label>產品類別</label>
                <input type="text" class="form-control" id="CTitle">
            </div>            
            <div class="form-group">
                <div class="col-md-2 col-md-10">
                    <button type="submit" id="btnSubmit" class="btn btn-primary">Submit</button>
                </div>
                <div>
                    <span id="msg" class="bg-danger"></span>
                </div>
            </div>
        </div>
    </div>

    <script type="text/javascript">
        //var query = window.location.search;
        //console.log("window.location.search:" + query);
        //window.location.search:?id=ffd2823a-f739-4678-98b6-a4d7dfc482fa
        //var query0 = window.location.search.substring(0);
        //console.log("window.location.search.substring(0):" + query0);
        //window.location.search.substring(0):?id=ffd2823a-f739-4678-98b6-a4d7dfc482fa
        //var query1 = window.location.search.substring(1);
        //console.log("window.location.search.substring(1):" + query1);
        //window.location.search.substring(1):id=ffd2823a-f739-4678-98b6-a4d7dfc482fa

        function getQueryGetParams(variable) {
            var query = window.location.search.substring(1);
            var vars = query.split("&");
            for (var idxVar = 0; idxVar < vars.length; idxVar++) {
                var pair = vars[idxVar].split("=");
                if (pair[0] == variable)
                    return pair[1];
            }
            return "";
        }

        $(function () {
            var id = getQueryGetParams("id");
            $.ajax({
                type: "get",
                url: "/api/PCategory/getbyid?id=" + id,
                dataType: "json",
                success: function (result) {
                    $("#CTitle").val(result.cTitle);
                }
            });
        });

        $('#btnSubmit').click(function () {
            var id = getQueryGetParams("id");
            $.ajax({
                type: 'put',
                url: "/api/PCategory/update",
                dataType: "text",
                data: JSON.stringify({
                    CId: id,
                    CTitle: $("#CTitle").val()
                }),
                contentType: 'application/json',
                success: function (result) {
                    if (result == "1") {
                        $('#msg').text('成功更新');
                    }
                }
            });
        });


    </script>


</body>
</html>

分别为
GET类型
的 GetSpecificCategoryById
用来帮我们把资料查询用来后续回填至画面上

和PUT类型的
UpdateCategory
用来呼叫后端进行编辑的更新

运行效果
画面By CategoryID 回填

更改之前

执行编辑更新后

https://ithelp.ithome.com.tw/upload/images/20220113/20107452eS6rgQAeMa.png

扩充删除用的 Action Method

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using Net5EFCoreWebApiApp.Data;
using Net5EFCoreWebApiApp.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Net5EFCoreWebApiApp.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class PCategoryController : ControllerBase
    {        
        //Startup.cs中註冊EF服務後，就可在特定控制器藉由.net core預設DI，透過建構子去實踐存取ProductDbContext。
        private readonly ProductDbContext _dbContext;
        public PCategoryController(ProductDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        [HttpPost("Add")]
        public async Task<ActionResult<int>> AddProductCategory(PCategory pCategory)
        {
            if (pCategory == null)
                return NotFound();

            if (string.IsNullOrEmpty(pCategory.CTitle))
                return NotFound();

            pCategory.CId = Guid.NewGuid();
            _dbContext.PCategories.Add(pCategory);
            int RowCount = await _dbContext.SaveChangesAsync();
            return CreatedAtAction(nameof(AddProductCategory),RowCount);
        }

        [HttpGet("Show")]
        public async Task<ActionResult<List<PCategory>>> ShowProductCategory()
        {
            var categories = await _dbContext.PCategories.ToListAsync();
            return categories;
        }

        [HttpGet("GetById")]
        public async Task<ActionResult<PCategory>> GetSpecificCategoryById(string id)
        {
            if (string.IsNullOrWhiteSpace(id))
                return NotFound();

            var category = await _dbContext.PCategories.AsNoTracking()
                .FirstOrDefaultAsync(item=>item.CId==new Guid(id));
            return category;
        }

        [HttpPut("Update")]
        public async Task<ActionResult<int>> UpdateCategory(PCategory pCategory)
        {
            if (pCategory == null)
                return NotFound();

            if (string.IsNullOrEmpty(pCategory.CTitle))
                return NotFound();

            _dbContext.Entry(pCategory).State = EntityState.Modified;
            var count = await _dbContext.SaveChangesAsync();
            return count;
        }

        [HttpDelete("Delete")]
        public ActionResult<int> DeleteCategory(string id)
        {
            if (string.IsNullOrWhiteSpace(id))
                return NotFound();
            var category = _dbContext.PCategories.Find(new Guid(id));
            if (category == null)
                return NotFound();
            _dbContext.PCategories.Remove(category);
            return _dbContext.SaveChanges();
        }
    }
}

运行效果

https://ithelp.ithome.com.tw/upload/images/20220113/20107452ofmUqygJcA.png

删除这边的API访问我们采用同步的方式确保不会因为entity取到null造成null例外错误

在此会发现Entity Framework的更新写法怎么跟之前
在EntityFramework Core笔记（2）_CodeFirst配置_搭配MVC应用的开发_编辑、删除
所写的方式不一
样事实上在EntityFramework中有很多种更新的写法

在之前文章的.net core MVC这边
的更新我们采用的是直接

context. Update（实体）;
context. SaveChanges（）;-或 context. SaveChangesAsync();

https://ithelp.ithome.com.tw/upload/images/20220113/201074522xPPkWWb2b.png

而在.net core WebAPI这边
我们采用的是

context. Entry（实体）. State = EntityState.Modified;
context. SaveChanges（）;-或 context. SaveChangesAsync();

若想观察EF Core产生的SQL
指令我们可以到Startup.cs
引入using Microsoft.Extensions.Logging;
并调整ConfigureServices

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<MyTestDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("MyTestDbConn"))
               .UseLoggerFactory(LoggerFactory.Create(builder => builder.AddConsole()))                       
    );
    services.AddControllersWithViews();
}

再次執行編輯就可以觀察的到當執行SaveChange時候EF 底層實際執行的 SQL script
在輸出視窗中記得調整為你的.net core應用才看的到

預設是沒有帶實際參數值的版本

這裡只要啟動敏感資料log機制即可

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<MyTestDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("MyTestDbConn"))
               .UseLoggerFactory(LoggerFactory.Create(builder => builder.AddConsole()))
               .EnableSensitiveDataLogging()
    );
    services.AddControllersWithViews();
}

https://ithelp.ithome.com.tw/upload/images/20220113/20107452wzAlLOfjVF.png

在MVC這裡用的
context.Update(實體);
對應SQL語句

Executed DbCommand (4ms) [Parameters=[@p3='abffc939-0413-4e71-9565-7c48de43f8db', @p0='33', @p1='Ted' (Size = 4000), @p2='True'], CommandType='Text', CommandTimeout='30']
      SET NOCOUNT ON;
      UPDATE [Students] SET [Age] = @p0, [Name] = @p1, [Sex] = @p2
      WHERE [Id] = @p3;
      SELECT @@ROWCOUNT;

https://ithelp.ithome.com.tw/upload/images/20220113/20107452lknqt1ZHcY.png

https://ithelp.ithome.com.tw/upload/images/20220113/20107452z5ugcByExv.png

在WebAPI这里用的
context. Entry（实体）. State = EntityState.Modified;
对应SQL语句

Executed DbCommand (11ms) [Parameters=[@p1='f46104c4-7672-4db6-9d75-a1f038a16216', @p0='平板電腦' (Size = 100)], CommandType='Text', CommandTimeout='30']
      SET NOCOUNT ON;
      UPDATE [PCategories] SET [CTitle] = @p0
      WHERE [CId] = @p1;
      SELECT @@ROWCOUNT;

在执行到state变更的该句之前事实上
都还是处于Detached的状态

直到被标记为Modified后
才会被变更追踪

EF中EntityState共分为如下几种

namespace Microsoft.EntityFrameworkCore
{
    //
    // 摘要:
    //     The state in which an entity is being tracked by a context.
    public enum EntityState
    {
        //
        // 摘要:
        //     The entity is not being tracked by the context.
        Detached = 0,
        //
        // 摘要:
        //     The entity is being tracked by the context and exists in the database. Its property
        //     values have not changed from the values in the database.
        Unchanged = 1,
        //
        // 摘要:
        //     The entity is being tracked by the context and exists in the database. It has
        //     been marked for deletion from the database.
        Deleted = 2,
        //
        // 摘要:
        //     The entity is being tracked by the context and exists in the database. Some or
        //     all of its property values have been modified.
        Modified = 3,
        //
        // 摘要:
        //     The entity is being tracked by the context but does not yet exist in the database.
        Added = 4
    }
}

直接改之前MVC里面Update写法