我有一些关于自定义模型绑定,模型状态和数据注释的问题.
1)如果我的模型上有数据注释,那么在自定义模型绑定器中进行验证是否是多余的,因为这就是我认为的数据注释点.
2)为什么我的控制器将模型状态视为有效,即使它不是,主要是我使Name属性为null或太短.
3)将自定义模型绑定器视为构造方法是否可行,因为这是他们提醒我的.
首先是我的模型.
public class Projects
{
[Key]
[required]
public Guid ProjectGuid { get; set; }
[required]
public string AccountName { get; set; }
[required(ErrorMessage = "Project name required")]
[StringLength(128,ErrorMessage = "Project name cannot exceed 128 characters")]
[MinLength(3,ErrorMessage = "Project name must be at least 3 characters")]
public string Name { get; set; }
[required]
public long TotalTime { get; set; }
}
然后我使用自定义模型绑定器绑定模型的某些属性.请不要介意它只是试图让它运行然后重构它是快速和肮脏的.
public class ProjectModelBinder : IModelBinder
{
public object BindModel(ControllerContext controllerContext,ModelBindingContext bindingContext)
{
if (controllerContext == null)
{
throw new ArgumentNullException("controllerContext");
}
if (bindingContext == null)
{
throw new ArgumentNullException("bindingContext");
}
var p = new Project();
p.ProjectGuid = System.Guid.NewGuid();
p.AccountName = controllerContext.HttpContext.User.Identity.Name;
p.Name = controllerContext.HttpContext.Request.Form.Get("Name");
p.TotalTime = 0;
//
// Is this redundant because of the data annotations?!?!
//
if (p.AccountName == null)
bindingContext.ModelState.AddModelError("Name","Name is required");
if (p.AccountName.Length < 3)
bindingContext.ModelState.AddModelError("Name","Minimum length is 3 characters");
if (p.AccountName.Length > 128)
bindingContext.ModelState.AddModelError("Name","Maximum length is 128 characters");
return p;
}
}
现在我的控制器动作.
[HttpPost]
public ActionResult CreateProject([ModelBinder(typeof(ProjectModelBinder))]Project project)
{
//
// For some reason the model state comes back as valid even when I force an error
//
if (!ModelState.IsValid)
return Content(Boolean.FalseString);
//_projectRepository.CreateProject(project);
return Content(Boolean.TrueString);
}
编辑
我在另一个stackoverflow问题上找到了一些代码,但我不确定在哪个点上我会将以下值注入此possible solution.
创建新对象时我想要注入的内容：
var p = new Project();
p.ProjectGuid = System.Guid.NewGuid();
p.AccountName = controllerContext.HttpContext.User.Identity.Name;
p.Name = controllerContext.HttpContext.Request.Form.Get("Name");
p.TotalTime = 0;
public class ProjectModelBinder : DefaultModelBinder
{
public override object BindModel(ControllerContext controllerContext,ModelBindingContext bindingContext)
{
if (bindingContext.ModelType == typeof(Project))
{
ModelBindingContext newBindingContext = new ModelBindingContext()
{
ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(
() => new Project(),// construct a Project object,typeof(Project) // using the Project Metadata
),ModelState = bindingContext.ModelState,ValueProvider = bindingContext.ValueProvider
};
// call the default model binder this new binding context
return base.BindModel(controllerContext,newBindingContext);
}
else
{
return base.BindModel(controllerContext,bindingContext);
}
}
}
}
解决方法
如果从DefaultModelBinder继承,覆盖BindModel方法,调用base.BindModel方法然后进行手动更改(设置guid,帐户名和总时间),您会发现事情更容易.
1)完成验证是多余的.您可以编写代码来反映验证元数据,就像默认情况一样,或者只是删除数据注释验证,因为您没有在模型绑定器中使用它.
2)我不知道,似乎是正确的,您应该单步执行代码并确保自定义绑定器填充所有适用的规则.
3)这是一个肯定的工厂,但不是一个构造函数.
编辑：你不能更接近解决方案,只需在模型工厂函数中设置所需的属性
public class ProjectModelBinder : DefaultModelBinder
{
public override object BindModel(ControllerContext controllerContext,ModelBindingContext bindingContext)
{
if (bindingContext.ModelType == typeof(Project))
{
ModelBindingContext newBindingContext = new ModelBindingContext()
{
ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(
() => new Project() // construct a Project object
{
ProjectGuid = System.Guid.NewGuid(),AccountName = controllerContext.HttpContext.User.Identity.Name,// don't set name,thats the default binder's job
TotalTime = 0,},typeof(Project) // using the Project Metadata
),ValueProvider = bindingContext.ValueProvider
};
// call the default model binder this new binding context
return base.BindModel(controllerContext,newBindingContext);
}
else
{
return base.BindModel(controllerContext,bindingContext);
}
}
}
或者您可以替代地覆盖CreateModel方法：
protected override object CreateModel(ControllerContext controllerContext,ModelBindingContext bindingContext,System.Type modelType)
{
if (modelType == typeof(Project))
{
Project model = new Project()
{
ProjectGuid = System.Guid.NewGuid(),thats the default binder's job
TotalTime = 0,};
return model;
}
throw new NotSupportedException("You can only use the ProjectModelBinder on parameters of type Project.");
}
