具有不同 Sql Table 的动态下拉列表作为视图 MVC C#

Question

我有一个 SQL 服务器 table 作为 CRUD 命令的来源。 table2_ID 列来自 table2（外键）。现在，在编辑和创建 Table1 条目时，我想要 Table1 中的 table_ID 列的下拉列表，选项为：Table2 的 Name，然后必须将 ID 保存为值。

控制器中从 Table2 获取数据（名称和 ID）的代码是什么样的？以及在视图中将数据显示为下拉列表并将名称作为选项并将 ID 作为值的代码是什么样的？

表 1:

number	table2_ID	date
11	2	12.12.2021
32	3	13.12.2021

表2

ID	name
2	axis
3	bot

    / GET: Table1/Edit/5
        public async Task<IActionResult> Edit(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }        
 
            var table1 = await _context.Table1.FindAsync(id);
            if (table1 == null)
            {
                return NotFound();
            }
            return View(table1);
        }

    [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("number, table2_ID, date")]       Table1 table1)
        {
            if (ModelState.IsValid)
            {
                _context.Add(table1);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }
            return View(table1);
        }
    //Create view 
<div class="row">
    <div class="col-md-4">
        <form asp-action="Create">
            <div class="form-group">
                <label asp-for="number" class="control-label"></label>
                <input asp-for="number" class="form-control" />
                <span asp-validation-for="number" class="text-danger"></span>
            </div>
 
            <div class="form-group">
                <label asp-for="table2_ID" class="control-label"></label> 
                <input asp-for="table2_ID" class="form-control" />
                <span asp-validation-for="table2_ID" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="date" class="control-label"></label>
                <input asp-for="date" class="form-control" />
                <span asp-validation-for="date" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>

Answer 1

What does the code in the controller look like to get the data from Table2 (name and ID)?

您可以得到如下表2的数据：

var data = _context.Table2.ToList();

and what does the code look like in the view to show the data as a dropdown with name as an option and id as a value

您需要先将下拉列表值存储在 ViewBag:

 ViewBag.table2= new SelectList(data,"ID","name");

并使用如下 ViewBag：

<select asp-for="Table2_ID" asp-items="@ViewBag.table2" class="form-control">
     <option selected disabled value="">--- Choose ---</option>
</select>

整个工作演示：

型号：

public class Table1 { 
    public int ID { get; set; } 
    public DateTime date { get; set; } 
    public string Table2_ID { get; set; } 
}
public class Table2 { 
    public int ID { get; set; } 
    public string name { get; set; } 
}

查看：

@model Table1

<div class="row">
    <div class="col-md-4">
        <form asp-action="Create">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="date" class="control-label"></label>
                <input asp-for="date" class="form-control" />
                <span asp-validation-for="date" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="Table2_ID" class="control-label"></label>
                <select asp-for="Table2_ID" asp-items="@ViewBag.table2"   class="form-control">
                        <option selected disabled value="">--- Choose ---</option>
                </select>
                <span asp-validation-for="Table2_ID" class="text-danger"></span>
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-primary" />
            </div>
        </form>
    </div>
</div>

控制器：

// GET: Table1/Create
public IActionResult Create()
{
    ViewBag.table2 = new SelectList(_context.Table2.ToList(), "ID", "name");

    return View();
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("ID,date,Table2_ID")] Table1 table1)
{
    if (ModelState.IsValid)
    {
        _context.Add(table1);
        await _context.SaveChangesAsync();
        return RedirectToAction(nameof(Index));
    }
    ViewBag.table2 = new SelectList(_context.Table2.ToList(), "ID", "name",table1.Table2_ID);
    return View(table1);
}

数据库上下文：

public class MyContext : DbContext
{
    public MyContext(DbContextOptions<MyContext> options)
        : base(options)
    {
    }

    public DbSet<Table1> Table1 { get; set; }
    public DbSet<Table2> Table2 { get; set; }     
}

结果：

具有不同 Sql Table 的动态下拉列表作为视图 MVC C#

Dynamic Dropdown with different Sql Table as the View MVC C#

html

c#

model-view-controller

drop-down-menu

asp.net-core-mvc