Asp.net MVC源码分析--Model Validation(Server端)实现(1)

一.MVC Validation 用法:
在Asp.net MVC 框架中如果需要对Model 对象加入验证,我们可以在Model的属性上标记所有继承于ValidationAttribute的Attribute特性.
例如下面的代码中,StringLength/Range/Compare 都是继承于ValidationAttribute类.
public class LogOnModel
    {
        [Required]
        [StringLength(10)]
        public string UserName { get; set; }

        [Required]
        [Range(5,10)]
        public string Password { get; set; }

[Compare("NewPassword", ErrorMessage = "The new password and confirmation password do not match.")]
public string ConfirmPassword { get; set; }

        [Display(Name = "Remember me?")]
        public bool RememberMe { get; set; }
    }
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在Action 中我们可以调用 ValidateModel 方法对Model对象进行验证,如果验证没有通过则会抛出InvalidOperationException异常，同时ModelState.IsValid状态为false
   [HttpPost]
        public ActionResult LogOn(LogOnModel model, string returnUrl)
        {
            this.ValidateModel(model);
            if (ModelState.IsValid)
            {
                if (MembershipService.ValidateUser(model.UserName, model.Password))
                {
                    FormsService.SignIn(model.UserName, model.RememberMe);
                    if (Url.IsLocalUrl(returnUrl))
                    {
                        return Redirect(returnUrl);
                    }
                    else
                    {
                        return RedirectToAction("Index", "Home");
                    }
                }
                else
                {
                    ModelState.AddModelError("", "The user name or password provided is incorrect.");
                }
            }

            // If we got this far, something failed, redisplay form
            return View(model);
        }
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这里需要注意的是如果我们不调用ValidateModel 方法Action上的Model对象默认也是能够验证的，这是因为在绑定对象阶段DefaultModelBinder.BindComplexElementalModel方法中MVC触发了验证的方法。
DefaultModelBinder.cs
internal void BindComplexElementalModel(ControllerContext controllerContext, ModelBindingContext bindingContext, object model) {
            // need to replace the property filter + model object and create an inner binding context
            ModelBindingContext newBindingContext = CreateComplexElementalModelBindingContext(controllerContext, bindingContext, model);

            // validation
            if (OnModelUpdating(controllerContext, newBindingContext)) {
                BindProperties(controllerContext, newBindingContext);
                OnModelUpdated(controllerContext, newBindingContext);
            }
        }
protected virtual void OnModelUpdated(ControllerContext controllerContext, ModelBindingContext bindingContext) {
            Dictionary<string, bool> startedValid = new Dictionary<string, bool>(StringComparer.OrdinalIgnoreCase);

foreach (ModelValidationResult validationResult in ModelValidator.GetModelValidator(bindingContext.ModelMetadata, controllerContext).Validate(null)) {
string subPropertyName = CreateSubPropertyName(bindingContext.ModelName, validationResult.MemberName);

                if (!startedValid.ContainsKey(subPropertyName)) {
                    startedValid[subPropertyName] = bindingContext.ModelState.IsValidField(subPropertyName);
                }

                if (startedValid[subPropertyName]) {
                    bindingContext.ModelState.AddModelError(subPropertyName, validationResult.Message);
                }
            }
        }
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二.ValidateModel方法源码分析
下面我们看一下MVC 是如何实现ValidateModel方法验证的.
1 protected internal void ValidateModel(object model) {
2             ValidateModel(model, null /* prefix */);
3     &n

补充：Web开发 , ASP.Net ,