【发布时间】：2020-09-03 03:27:21
【问题描述】：
我正在为 Uni 的 ASP.NET 类创建一个简单的 MVC 项目。 它由一个模型类（BikeAds）、控制器（BikeAdsController）和视图（创建、删除、详细信息、编辑、索引）组成，并使用 mdf 文件作为数据库。
控制器和视图是自动生成的（我选择了“带有视图的 MVC 控制器，使用实体框架”）。
我在尝试创建新条目时遇到了问题。当我填写“创建”表单并单击“提交”按钮时，它会清除输入字段中的所有数据并且不会提交表单 - 验证不允许空字段。当我删除 [Required] 验证时，我得到了一个 SQL 异常（数据库中不允许 null）。
我不明白问题的原因在哪里。
控制器：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using bikes_ads.Data;
using bikes_ads.Models;
namespace bikes_ads.Controllers
{
public class BikeAdsController : Controller
{
private readonly BikesAdvertsDbContext _context;
public BikeAdsController(BikesAdvertsDbContext context)
{
_context = context;
}
// GET: BikeAds
public async Task<IActionResult> Index()
{
return View(await _context.Adverts.ToListAsync());
}
// GET: BikeAds/Details/5
public async Task<IActionResult> Details(int? id)
{
if (id == null)
{
return NotFound();
}
var bikeAd = await _context.Adverts
.FirstOrDefaultAsync(m => m.Id == id);
if (bikeAd == null)
{
return NotFound();
}
return View(bikeAd);
}
// GET: BikeAds/Create
public IActionResult Create()
{
return View();
}
**// POST: BikeAds/Create
// To protect from overposting attacks, enable the specific properties you want to bind to, for
// more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("Id")] BikeAd bikeAd)
{
if (ModelState.IsValid)
{
_context.Add(bikeAd);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
return View(bikeAd);
}**
// GET: BikeAds/Edit/5
public async Task<IActionResult> Edit(int? id)
{
if (id == null)
{
return NotFound();
}
var bikeAd = await _context.Adverts.FindAsync(id);
if (bikeAd == null)
{
return NotFound();
}
return View(bikeAd);
}
// POST: BikeAds/Edit/5
// To protect from overposting attacks, enable the specific properties you want to bind to, for
// more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Edit(int id, [Bind("Id")] BikeAd bikeAd)
{
if (id != bikeAd.Id)
{
return NotFound();
}
if (ModelState.IsValid)
{
try
{
_context.Update(bikeAd);
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!BikeAdExists(bikeAd.Id))
{
return NotFound();
}
else
{
throw;
}
}
return RedirectToAction(nameof(Index));
}
return View(bikeAd);
}
// GET: BikeAds/Delete/5
public async Task<IActionResult> Delete(int? id)
{
if (id == null)
{
return NotFound();
}
var bikeAd = await _context.Adverts
.FirstOrDefaultAsync(m => m.Id == id);
if (bikeAd == null)
{
return NotFound();
}
return View(bikeAd);
}
// POST: BikeAds/Delete/5
[HttpPost, ActionName("Delete")]
[ValidateAntiForgeryToken]
public async Task<IActionResult> DeleteConfirmed(int id)
{
var bikeAd = await _context.Adverts.FindAsync(id);
_context.Adverts.Remove(bikeAd);
await _context.SaveChangesAsync();
return RedirectToAction(nameof(Index));
}
private bool BikeAdExists(int id)
{
return _context.Adverts.Any(e => e.Id == id);
}
}
}
创建表单：
@model bikes_ads.Models.BikeAd
@{
ViewData["Title"] = "Create";
}
<h1>Create</h1>
<h4>BikeAd</h4>
<hr />
<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="Title" class="control-label"></label>
<input asp-for="Title" class="form-control" />
<span asp-validation-for="Title" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Category" class="control-label"></label>
<input asp-for="Category" class="form-control" />
<span asp-validation-for="Category" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="ShortDescription" class="control-label"></label>
<input asp-for="ShortDescription" class="form-control" />
<span asp-validation-for="ShortDescription" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="LongDescription" class="control-label"></label>
<input asp-for="LongDescription" class="form-control" />
<span asp-validation-for="LongDescription" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="SellerName" class="control-label"></label>
<input asp-for="SellerName" class="form-control" />
<span asp-validation-for="SellerName" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="SellerPhoneNumber" class="control-label"></label>
<input asp-for="SellerPhoneNumber" class="form-control" />
<span asp-validation-for="SellerPhoneNumber" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Price" class="control-label"></label>
<input asp-for="Price" class="form-control" />
<span asp-validation-for="Price" class="text-danger"></span>
</div>
<div class="form-group">
<input type="submit" value="Create" class="btn btn-primary" />
</div>
</form>
</div>
</div>
<div>
<a asp-action="Index">Back to List</a>
</div>
@section Scripts {
@{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}
模型类：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.ComponentModel.DataAnnotations;
namespace bikes_ads.Models
{
public class BikeAd
{
[Key]
public int Id { get; set; }
[Required]
[MaxLength(50)]
public string Title { get; set; }
[Required]
public string Category { get; set; }
[Required]
[MaxLength(100)]
public string ShortDescription { get; set; }
[Required]
[MaxLength(500)]
public string LongDescription { get; set; }
[Required]
public string SellerName { get; set; }
[Required]
public string SellerPhoneNumber { get; set; }
[Required]
public double Price { get; set; }
public BikeAd(int id, string title, string category, string shortDescription, string longDescription, string sellerName, string sellerPhoneNumber, double price)
{
Id = id;
Title = title;
Category = category;
ShortDescription = shortDescription;
LongDescription = longDescription;
SellerName = sellerName;
SellerPhoneNumber = sellerPhoneNumber;
Price = price;
}
public BikeAd()
{
}
}
}
【问题讨论】：
标签： c# asp.net asp.net-mvc visual-studio entity-framework