请注意到，这个Validate()方法调用了另一个GetRuleViolations()方法。如果存在任何校验错误，那么该Validate()方法即抛出一个RuleViolationException型异常。
在论坛应用程序中，该Validate()方法是在ForumRepository中被调用的。在把一个新消息添加到数据库中之前,在Message类上调用这个Validate()方法，如下所示：
public Message AddMessage(Message messageToAdd)
{
messageToAdd.Validate();
_dataContext.Insert(messageToAdd);
return messageToAdd;
}
{
messageToAdd.Validate();
_dataContext.Insert(messageToAdd);
return messageToAdd;
}
如果存在一个校验错误，那么将抛出一个RuleViolationException型异常，并且永不会把相应的消息插入到数据库中。
该ForumRepository应用于论坛控制器内。当你提交一个表单用以创建一个新的论坛消息时，ForumController.Create(FormCollection collecction)方法即被调用。列表6中提供了论坛控制器完整的实现代码。
列表6–ForumController.cs
using System;
using System.Web.Mvc;
using MvcForums.Models;
using Microsoft.Web.Mvc;
using MvcForums.Models.Entities;
using MvcValidation;
namespace MvcForums.Controllers
{
public class ForumController : Controller
{
private IForumRepository _repository;
public ForumController()
: this(new ForumRepository())
{ }
public ForumController(IForumRepository repository)
{
_repository = repository;
}
public ActionResult Index()
{
ViewData.Model = _repository.SelectThreads();
return View("Index");
}
[AcceptVerbs("GET")]
public ActionResult Create()
{
return View("Create");
}
[AcceptVerbs("Post")]
public ActionResult Create(FormCollection form)
{
var messageToCreate = new Message();
try
{
UpdateModel(messageToCreate, new[] { "Author", "ParentThreadId", "ParentMessageId", "Subject", "Body" });
_repository.AddMessage(messageToCreate);
}
catch (RuleViolationException rex)
{
Validation.UpdateModelStateWithViolations(rex, ViewData.ModelState);
return View("Create", messageToCreate);
}
catch (Exception ex)
{
ViewData.ModelState.AddModelError("message", null, "Could not save message.");
return View("Create", messageToCreate);
}
// Redirect
return RedirectToAction("Index");
}
public ActionResult Thread(int threadId)
{
ViewData.Model = _repository.SelectMessages(threadId);
return View("Thread");
}
}
}
using System.Web.Mvc;
using MvcForums.Models;
using Microsoft.Web.Mvc;
using MvcForums.Models.Entities;
using MvcValidation;
namespace MvcForums.Controllers
{
public class ForumController : Controller
{
private IForumRepository _repository;
public ForumController()
: this(new ForumRepository())
{ }
public ForumController(IForumRepository repository)
{
_repository = repository;
}
public ActionResult Index()
{
ViewData.Model = _repository.SelectThreads();
return View("Index");
}
[AcceptVerbs("GET")]
public ActionResult Create()
{
return View("Create");
}
[AcceptVerbs("Post")]
public ActionResult Create(FormCollection form)
{
var messageToCreate = new Message();
try
{
UpdateModel(messageToCreate, new[] { "Author", "ParentThreadId", "ParentMessageId", "Subject", "Body" });
_repository.AddMessage(messageToCreate);
}
catch (RuleViolationException rex)
{
Validation.UpdateModelStateWithViolations(rex, ViewData.ModelState);
return View("Create", messageToCreate);
}
catch (Exception ex)
{
ViewData.ModelState.AddModelError("message", null, "Could not save message.");
return View("Create", messageToCreate);
}
// Redirect
return RedirectToAction("Index");
}
public ActionResult Thread(int threadId)
{
ViewData.Model = _repository.SelectMessages(threadId);
return View("Thread");
}
}
}
注意，这里存在两个Create()方法。第一个Create()方法仅当发生一次HTTP GET操作时才被调用。这个行为返回的表单将用于创建一个新的消息
