使用EF，采用DataBase 模式，实体类都是按照数据库的定义自动生成，我们似乎无法干预。如果要生成自定义的实体类，该怎么做呢？
思路是这样的：
1、我们要自定义生成的实体类，都是分部类（partial)，目的是对EF生成的实体类进行扩充；
2、扩充部分，预先写好在模板里，自动生成
3、每个实体类，都进行扩充
实施方法：
1、给VS2012安装两个插件：
Devart T4 Editor：为VS提供智能提示功能。T4 Toolbox：在生成多文件时很有用。2、新建文件夹T4，存放模板文件
1）创建T4 Toolbox模板文件EntityTemplate.tt，作用是生成多个实体类文件
代码如下：
<#+// <copyright file="Entity.tt" company="cqxm">// Copyright © . All Rights Reserved.// </copyright>public class Entity : CSharpTemplate{private string _className;public Entity(string className){_className = className;}public override string TransformText(){base.TransformText();#>namespace testEF{public partial class <#= _className #> : IEntity{public string _ID{get{return Id.ToString();}}}}<#+return this.GenerationEnvironment.ToString();}}#>2）创建T4模板文件EntityOutput.tt，调用前面写的EntityTemplate.tt，，真正生成各种实体类文件
<#@ template debug="false" hostspecific="false" language="C#" #><#@ assembly name="System.Core" #><#@ import namespace="System.IO" #><#@ import namespace="System.Linq" #><#@ import namespace="System.Text" #><#@ import namespace="System.Collections.Generic" #><#@ include file="EF.Utility.CS.ttinclude"#><#@ include file="T4Toolbox.tt" #><#@ include file="EntityTemplate.tt" #><#string curPath = Path.GetDirectoryName(Host.TemplateFile);string destPath = Path.Combine(curPath, @"..\Partial");//将各个扩充实体类文件生成到文件夹Partial下if(!Directory.Exists(destPath)){Directory.CreateDirectory(destPath);}const string inputFile = @"..\ShowMe.edmx";var textTransform = DynamicTextTransformation.Create(this);var itemCollection = new EdmMetadataLoader(textTransform.Host, textTransform.Errors).CreateEdmItemCollection(inputFile);foreach (var entity in GetItemsToGenerate<EntityType>(itemCollection)){//每个实体类都要自动生成扩充文件，是自动哦，参考文章里介绍的是手动输入实体类名称Entity template = new Entity(entity.Name);string fileName = string.Format(@"{0}\{1}.cs", destPath, entity.Name);template.Output.Encoding = Encoding.UTF8;if(File.Exists(fileName)){File.Delete(fileName);}template.RenderToFile(fileName);}#><#+/*以下代码都是为了获得EF自动生成的所有实体类名单，抄自 *.edmx\*.Context.tt。没办法，谁叫俺看不懂哪些代码呢*/public class EdmMetadataLoader{private readonly IDynamicHost _host;private readonly System.Collections.IList _errors;public EdmMetadataLoader(IDynamicHost host, System.Collections.IList errors){ArgumentNotNull(host, "host");ArgumentNotNull(errors, "errors");_host = host;_errors = errors;}public IEnumerable<GlobalItem> CreateEdmItemCollection(string sourcePath){ArgumentNotNull(sourcePath, "sourcePath");if (!ValidateInputPath(sourcePath)){return new EdmItemCollection();}var schemaElement = LoadRootElement(_host.ResolvePath(sourcePath));if (schemaElement != null){using (var reader = schemaElement.CreateReader()){IList<EdmSchemaError> errors;var itemCollection = MetadataItemCollectionFactory.CreateEdmItemCollection(new[] { reader }, out errors);ProcessErrors(errors, sourcePath);return itemCollection;}}return new EdmItemCollection();}public string GetModelNamespace(string sourcePath){ArgumentNotNull(sourcePath, "sourcePath");if (!ValidateInputPath(sourcePath)){return string.Empty;}var model = LoadRootElement(_host.ResolvePath(sourcePath));if (model == null){return string.Empty;}var attribute = model.Attribute("Namespace");return attribute != null ? attribute.Value : "";}private bool ValidateInputPath(string sourcePath){if (sourcePath == "$" + "edmxInputFile" + "$"){_errors.Add(new CompilerError(_host.TemplateFile ?? sourcePath, 0, 0, string.Empty,GetResourceString("Template_ReplaceVsItemTemplateToken")));return false;}return true;}public XElement LoadRootElement(string sourcePath){ArgumentNotNull(sourcePath, "sourcePath");var root = XElement.Load(sourcePath, LoadOptions.SetBaseUri | LoadOptions.SetLineInfo);return root.Elements().Where(e => e.Name.LocalName == "Runtime").Elements().Where(e => e.Name.LocalName == "ConceptualModels").Elements().Where(e => e.Name.LocalName == "Schema").FirstOrDefault()?? root;}private void ProcessErrors(IEnumerable<EdmSchemaError> errors, string sourceFilePath){foreach (var error in errors){_errors.Add(new CompilerError(error.SchemaLocation ?? sourceFilePath,error.Line,error.Column,error.ErrorCode.ToString(CultureInfo.InvariantCulture),error.Message){IsWarning = error.Severity == EdmSchemaErrorSeverity.Warning});}}public bool IsLazyLoadingEnabled(EntityContainer container){string lazyLoadingAttributeValue;var lazyLoadingAttributeName = MetadataConstants.EDM_ANNOTATION_09_02 + ":LazyLoadingEnabled";bool isLazyLoading;return !MetadataTools.TryGetStringMetadataPropertySetting(container, lazyLoadingAttributeName, out lazyLoadingAttributeValue)|| !bool.TryParse(lazyLoadingAttributeValue, out isLazyLoading)|| isLazyLoading;}}public static void ArgumentNotNull<T>(T arg, string name) where T : class{if (arg == null){throw new ArgumentNullException(name);}}private static readonly Lazy<System.Resources.ResourceManager> ResourceManager =new Lazy<System.Resources.ResourceManager>(() => new System.Resources.ResourceManager("System.Data.Entity.Design", typeof(MetadataItemCollectionFactory).Assembly), isThreadSafe: true);public static string GetResourceString(string resourceName){ArgumentNotNull(resourceName, "resourceName");return ResourceManager.Value.GetString(resourceName, null);}private const string ExternalTypeNameAttributeName = @":ExternalTypeName";public IEnumerable<T> GetItemsToGenerate<T>(IEnumerable<GlobalItem> itemCollection) where T: EdmType{return itemCollection.OfType<T>().Where(i => !i.MetadataProperties.Any(p => p.Name == ExternalTypeNameAttributeName)).OrderBy(i => i.Name);}#>生成各种实体类文件的方法很简单，只要保存一下这个EntityOutput.tt文件，各种实体类文件即可应声生成，很爽。
最后生成的文件如蓝线圈圈所示
分之百的把自己推销给自己。
