如何使用[override modelmetadata]事件[动态]添加自定义属性？

本文介绍了如何使用[override modelmetadata]事件[动态]添加自定义属性？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 亲爱的， 我想做一些奇怪的工作： 动态地向我的模型类添加属性没有直接在模型类的每个属性上添加这些属性。 整个故事是： 我有一个使用Code首先使用域驱动设计的MVC项目，所以我有以下内容： 核心类：员工存在于DDD.Core项目中 模型类：EmployeeModel存在于DDDApp项目中[主应用程序] 现在，我希望Model类[EmployeeModel]具有核心类[Employee]的映射属性。 注意： 为了不破坏设计，我不应该在DDDApp中添加DDD.Core的引用。 我尝试了什么： 其实我在这方面取得了很大的进步： /> 在 global.asax 文件中我已经加载了所有DDD.Core类 Dears,I want to do some weird job which is: adding attributes dynamically to my model class without adding these attributes directly on each property in the model class.the whole story is:I have an MVC project using Code first with domain driven design so i have the following:Core Class : Employee exists in DDD.Core ProjectModel Class : EmployeeModel exists in DDDApp Project [main App]Now, i wants Model class [EmployeeModel] to have the mapped attributes of core class [Employee].Note: To not break down the design, i should not add reference of DDD.Core in DDDApp.What I have tried:Actually i made a good progress in that:In global.asax File i have loaded all of the DDD.Core classesstring webRootPath = HttpContext.Current.Server.MapPath("~"); string docPath = Path.GetFullPath(Path.Combine(webRootPath, "..\\DDD.Core\\bin\\Debug\\DDD.Core.dll")); Assembly DDDCore = Assembly.LoadFile(docPath); Application["DDDCoreAssembly"] = DDDCore; 在我继承的 DataAnnotationsModelMetadataProvider类中，我做了以下代码： In DataAnnotationsModelMetadataProvider class which i inherit, i did the following code:public class MetadataProvider : DataAnnotationsModelMetadataProvider { protected override ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType, Func<object> modelAccessor, Type modelType, string propertyName) { //All DDD.Core Asembly which contains the core classes Assembly DDDCoreAssembly = HttpContext.Current.Application["DDDCoreAssembly"] as Assembly; if (containerType != null) { //Get the Core Class Employee for example. Type coreModelType = DDDCoreAssembly.GetTypes().Single(x => x.Name == containerType.Name.Replace("Model", "")); //Get Employee Class Property MemberInfo coreClassProperty = coreModelType.GetProperty(propertyName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (coreClassProperty != null) { //Get All Attributes of CoreClass Property object[] coreClassPropertyAttributes = coreClassProperty.GetCustomAttributes(true); foreach (var item in coreClassPropertyAttributes) { if (item.GetType() == typeof(RequiredAttribute)) { RequiredAttribute ra = new RequiredAttribute(); //######################### //Now, I can't add this attribute to the property dynamically (Any Ideas) //######################### } else if (item.GetType() == typeof(StringLengthAttribute)) { StringLengthAttribute sla = new StringLengthAttribute(((System.ComponentModel.DataAnnotations.StringLengthAttribute)(item)).MaximumLength); sla.MinimumLength = ((System.ComponentModel.DataAnnotations.StringLengthAttribute)(item)).MinimumLength; sla.ErrorMessage = "el length ya ged3an"; //######################### //Now, I can't add this attribute to the property dynamically (Any Ideas) //######################### } else if (item.GetType() == typeof(RegularExpressionAttribute)) { } } } } var result = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName); //************************* //This Part of Code is used for localization //************************* if (string.IsNullOrEmpty(result.DisplayName) && containerType != null && propertyName != null) { var keyForDisplayValue = string.Format("{0}_{1}", containerType.Name, propertyName); var translatedValue = MCITemplateV4.Properties.Resources.ResourceManager.GetObject(keyForDisplayValue) as string; if (!string.IsNullOrEmpty(translatedValue)) { result.DisplayName = translatedValue; } } return result; } } 我无法添加最后一步，即添加属性动态属性？ 那么任何人都能帮助我吗？!!!! I just can't add the final step which is adding attributes to the properties dynamically?So Can any one help me with that?!!!!推荐答案 听起来不可能 - 至少我想不出办法来做... 无论如何有些想法： 你的意思是你不能添加对你的核心DLL的引用？无论如何，当你反思时，你会给它一个硬编码参考（更好的依赖），不是吗？ 你为什么不使用任何标准模式出于这种问题？ *创建一个包装器并在那里添加属性（如果可以的话，将比向原始类添加属性的代码更多） *使用一些二进制重写器和AOP（在本机.NET中尚未提供，但我听说过一些第三方产品（代码签约等）） *生成具有属性的类以节省打字工作（我认为这是大多数工具所做的，使用T4来定义代码生成器） *编写一些VS（IDE）扩展来添加或（预）处理模型文件并添加属性编译。 *如果只是你正在使用这些属性（我不认为是这种情况，你似乎计划使用验证器）你可以为你的模型类型操作TypeDescriptor（其中属性可以动态添加AFAI K） 所以也许你可以找到另一种方式（我曾经用T4为整个模型类解决了类似的问题） 祝你的项目好运！Sounds impossible - at least I can't think about a way to do it...Anyway some thoughts:What do you mean you can't add a reference to your core dll? But you crate a "hardcoded" reference (better dependency) to it anyway when reflecting, don't you?Why don't you use any of the "Standard Patterns" for this kind of Problem? * create a wrapper and add the attributes there (would be more code than adding the attributes to the original classes, if you can) * Use some binary rewriter and AOP (not yet available in native .NET, but I heard about some 3rd Party products (codecontracts etc.)) * Generate the classes with the attributes to save typing work (I think this is what most Tools do, use T4 to define the code Generator) * Write some VS (IDE) Extension to add or (pre-)process the model files and add the attributes before compilation.* If only you are consuming the attributes (I don't think this is the case, it seems you plan use by a validator) you can manipulate the TypeDescriptor for your model types (where Attributes can be added dynamically AFAIK)so maybe you can find another way (I did once solve a similar problem with T4 generated templates for the whole model class)Good luck with your Project! 这篇关于如何使用[override modelmetadata]事件[动态]添加自定义属性？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！