[英]Is there a way to reuse data annotations?
Is there a way to implement the idea of a data domains (at a property level) inside of a class that is used as a model in a view in ASP.Net MVC 4? 有没有办法在ASP.Net MVC 4中的视图中用作模型的类内部实现数据域(在属性级别)的概念?
Consider this code: 考虑以下代码:
public class LoginProfileModel {
[DisplayName("Login ID")]
[Required(ErrorMessage = "Login ID is required.")]
public string LogonID { get; set; }
[DisplayName("Password")]
[Required(ErrorMessage = "Password cannot be blank.")]
[StringLength(20, MinimumLength = 3)]
[DataType(DataType.Password)]
public string Password { get; set; }
}
Here is a LoginProfileModel in for ASP.Net MVC 4. It uses a variety of metadata/data annotations so that I can create a clean view with this code: 这是ASP.Net MVC 4中的LoginProfileModel。它使用各种元数据/数据注释,以便我可以使用以下代码创建一个干净的视图:
@model myWebSite.Areas.People.Models.LoginProfileModel
@using ( Html.BeginForm( "Index" , "Login" ) ) {
@Html.ValidationSummary()
@Html.EditorForModel()
<input type="submit" value="Login" />
}
I use the idea of a "Login ID" and a "Password" in more than one view, and therefore, in more than one view model. 我在多个视图中使用“登录ID”和“密码”的概念,因此,在多个视图模型中使用。 I want to be able to define the attributes that a Password uses, or possibly the Password itself with all of it's data annotations in a single location so that I can reuse all those definitions where needed, rather than respecifying them every time they are used:
我希望能够在一个位置定义密码使用的属性,或者可能是密码本身以及所有这些数据注释,以便我可以在需要时重用所有这些定义,而不是每次使用时重新指定它们:
[DisplayName("Password")]
[Required(ErrorMessage = "Password cannot be blank.")]
[StringLength(20, MinimumLength = 3)]
[DataType(DataType.Password)]
public string Password { get; set; }
Is that possible some way? 这有可能吗?
The following attributes affect the validation process of your View. 以下属性会影响View的验证过程。
[Required(ErrorMessage = "Password cannot be blank.")]
[StringLength(20, MinimumLength = 3)]
For the Validation attributes, you can create a class like this: 对于Validation属性,您可以创建如下的类:
public class PasswordRuleAttribute : ValidationAttribute
{
public override bool IsValid(object value)
{
if (new RequiredAttribute { ErrorMessage = "Password cannot be blank." }.IsValid(value) && new StringLengthAttribute(20) { MinimumLength=3 }.IsValid(value) )
return true;
return false;
}
}
You can use it as follows: 您可以按如下方式使用它:
[PasswordRule]
public string Password{get;set;}
The other two attributes that you mentioned are Directly derived from the Attribute
class, and I don't think there's a way to consolidate them into a single attribute. 您提到的其他两个属性是直接从
Attribute
类派生的,我认为没有办法将它们合并为单个属性。
I'll update you with an edit soon. 我很快就会通过编辑为您更新。
So now we're left with: 所以现在我们离开了:
[DisplayName("Password")]
[DataType(DataType.Password)]
[PasswordRule]
public string Password{get;set;}
EDIT: 编辑:
According to this post: Composite Attribute , it's not possible to merge attributes. 根据这篇文章: 复合属性 ,不可能合并属性。
You can do this using a buddy class, which provides metadata for your view model. 您可以使用伙伴类来执行此操作,该类为视图模型提供元数据。 Like so:
像这样:
public partial class LogonMetaData
{
[DisplayName("Login ID")]
[Required(ErrorMessage = "Login ID is required.")]
public string LogonID { get; set; }
[DisplayName("Password")]
[Required(ErrorMessage = "Password cannot be blank.")]
[StringLength(20, MinimumLength = 3)]
[DataType(DataType.Password)]
public string Password { get; set; }
}
Then your view models: 然后你的视图模型:
using System.ComponentModel.DataAnnotations;
[MetadataType(typeof(LogonMetaData))]
public partial class FirstViewModel
{
public string LogonID { get; set; }
public string Password { get; set; }
}
using System.ComponentModel.DataAnnotations;
[MetadataType(typeof(LogonMetaData))]
public partial class SecondViewModel
{
public string LogonID { get; set; }
public string Password { get; set; }
}
Note the use of partial
in the class definitions. 注意在类定义中使用
partial
。 This is what allows this approach to work. 这是允许这种方法工作的原因。 One caveat, other than the obvious problem with DRY, is that I believe the metadata class has to reside in the same namespace as your view models, else it complains.
除了DRY的明显问题之外,一个警告是,我认为元数据类必须与视图模型位于相同的命名空间中,否则它会抱怨。 Other than that, this should do what you want.
除此之外,这应该做你想要的。
As a corollary to John H's answer, you could just use inheritance and make those view models that have the "idea of a LogonId and password" inherit from that base view model. 作为John H的答案的必然结果,您可以使用继承并使那些具有“LogonId和密码的概念”的视图模型继承自该基本视图模型。 This would solve the MetaData issues that were mentioned in the previous answer.
这将解决前一个答案中提到的MetaData问题。
public class LoginProfileModel {
[DisplayName("Login ID")]
[Required(ErrorMessage = "Login ID is required.")]
public string LogonID { get; set; }
[DisplayName("Password")]
[Required(ErrorMessage = "Password cannot be blank.")]
[StringLength(20, MinimumLength = 3)]
[DataType(DataType.Password)]
public string Password { get; set; }
}
public SomeOtherClassThatNeedsLoginInfo : LoginProfileModel{
public string Property {get;set;}
}
Now in the SomeOtherClassThatNeedsLoginInfo, those properties and their related DataAnnotations will be available to you. 现在,在SomeOtherClassThatNeedsLoginInfo中,您可以使用这些属性及其相关的DataAnnotations。
Another idea would be just to pass that LoginInfo as a property on your other view models. 另一个想法是将LoginInfo作为属性传递给其他视图模型。
public SomeOtherClassThatNeedsLoginInfo{
public string Property {get;set;}
public LoginProfileModel LoginModel {get;set;}
}
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