新年首作ELinq+T4模版引擎制作多文件实体代码生成器

　　关于代码生成器的文章网上已经多的不能太多了，在6年前我写过两篇文章介绍代码生成器的，一篇主要代码生成器的7种模型架构设计思想：也谈代码生成器，另外一篇再谈代码生成器介绍了基于其中一种模型架构的实践文章，现在回顾一下6年前的文章拿到现在其设计思想也从不过时，呵呵自大了。好了废话不多说，今天给大家分享一下利用ELinq内置的数据库元数据模型和T4 模版引擎制作多文件实体代码生成器。（ELinq：是一个轻量简单易用的开源Linq ORM数据访问组件，支持Nullable类型和枚举类型，支持根据实体类自动建库建表建关系，支持根据数据库通过T4模版自动生成实体代码，对Linq 的谓词提供了完美的支持，旨在让绝大部份的主流数据库都使用 Linq 来进行程序开发，让开发人员访问数据库从SQL中解放出来，易学易用上手快，配置简单，并且提供了源代码下载，方便定制。支持多数据库，目前支持 Access、SQLServer、SqlCE、 SQLite、MySQL、ORACLE，未来还会支持更多的数据库）

　　本文使用以下工具：

VS2010 SP1
T4 模版引擎
ELinq 数据库元数据模型（借助ELinq强大的ORM框架，支持多种数据库）
SqlServer 数据库

操作步骤

创建控制台应用程序 Demo
通过Nuget添加ELinq 的引用：在Nuget控制台中输入：install-package ELinq, Nuget会自动的将你引用的库的这个库的依赖文件添加到你的项目引用中.

配置SqlServer数据库连接信息。添加App.Config 文件，并添加如下的配置信

<add name="Northwind" connectionString="Data Source=.;Initial Catalog=northwind;Persist Security Info=True;User ID=sa;Password="
providerName="System.Data.SqlClient" />

编译项目，保证ELinq已经输出到Bin目录下，为T4 模版准备

添加T4 文件，MultipleOutputHelper.ttinclude，该文件的作用是：生成多文件，获取当前活动项目的信息（配置文件路径，项目路径，数据路径，AppConfig等)

View Code

<#@ template language="C#" debug="True" hostspecific="True" #>
<#@ assembly name="System.Core"
#><#@ assembly name="EnvDTE"
#><#@ assembly name="System.Xml"
#><#@ assembly name="System.Xml.Linq"
#><#@ assembly name="System.Configuration" #>
<#@ import namespace="System"
#><#@ import namespace="System.CodeDom"
#><#@ import namespace="System.CodeDom.Compiler"
#><#@ import namespace="System.Collections.Generic"
#><#@ import namespace="System.IO"
#><#@ import namespace="System.Linq"
#><#@ import namespace="System.Reflection"
#><#@ import namespace="System.Text"
#><#@ import namespace="System.Xml.Linq"
#><#@ import namespace="Microsoft.VisualStudio.TextTemplating"
#><#@ import namespace="System.Configuration" #>
<#+
    public ConnectionStringSettings GetConnectionStringSettings(string connectionStringName){
        if (string.IsNullOrEmpty(connectionStringName))
            throw new ArgumentNullException("connectionStringName");
        var configFile = new ExeConfigurationFileMap();
        configFile.ExeConfigFilename = GetConfigPath();
        if (string.IsNullOrEmpty(configFile.ExeConfigFilename))
            throw new ArgumentNullException("The project does not contain App.config or Web.config file.");
        var config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration(configFile, ConfigurationUserLevel.None);
        var connSection = config.ConnectionStrings;
        var connectionStringSettings = connSection.ConnectionStrings[connectionStringName];
        if(connectionStringSettings == null)
            throw new ArgumentNullException("connectionStringName not exists");
        return connectionStringSettings;
    }
    public string GetConfigPath(){
        EnvDTE.Project project = GetCurrentProject();
        foreach (EnvDTE.ProjectItem item in project.ProjectItems){
            if (item.Name.Equals("App.config", StringComparison.InvariantCultureIgnoreCase) || item.Name.Equals("Web.config", StringComparison.InvariantCultureIgnoreCase))
            return GetProjectPath() + "\\" + item.Name;
        }
        return String.Empty;
    }
    public string GetProjectPath(){
        EnvDTE.Project project = GetCurrentProject();
        System.IO.FileInfo info = new System.IO.FileInfo(project.FullName);
        return info.Directory.FullName;
    }
    public string GetDataDirectory(){
        EnvDTE.Project project = GetCurrentProject();
        return System.IO.Path.GetDirectoryName(project.FileName) + "\\App_Data\\";
    }
    
    public EnvDTE.Project GetCurrentProject(){
        IServiceProvider _ServiceProvider = (IServiceProvider)Host;
        if (_ServiceProvider == null)
            throw new Exception("Host property returned unexpected value (null)");

        EnvDTE.DTE dte = (EnvDTE.DTE)_ServiceProvider.GetService(typeof(EnvDTE.DTE));
        if (dte == null)
            throw new Exception("Unable to retrieve EnvDTE.DTE");

        Array activeSolutionProjects = (Array)dte.ActiveSolutionProjects;
        if (activeSolutionProjects == null)
            throw new Exception("DTE.ActiveSolutionProjects returned null");

        EnvDTE.Project dteProject = (EnvDTE.Project)activeSolutionProjects.GetValue(0);
        if (dteProject == null)
            throw new Exception("DTE.ActiveSolutionProjects[0] returned null");

        return dteProject;
}
    // Manager class records the various blocks so it can split them up
class Manager {
    private class Block {
        public String Name;
        public int Start, Length;
        public bool IncludeInDefault;
    }

    private Block currentBlock;
    private List<Block> files = new List<Block>();
    private Block footer = new Block();
    private Block header = new Block();
    private ITextTemplatingEngineHost host;
    private StringBuilder template;
    protected List<String> generatedFileNames = new List<String>();

    public static Manager Create(ITextTemplatingEngineHost host, StringBuilder template) {
        return (host is IServiceProvider) ? new VSManager(host, template) : new Manager(host, template);
    }

    public void StartNewFile(String name) {
        if (name == null)
            throw new ArgumentNullException("name");
        CurrentBlock = new Block { Name = name };
    }

    public void StartFooter(bool includeInDefault = true) {
        CurrentBlock = footer;
        footer.IncludeInDefault = includeInDefault;
    }

    public void StartHeader(bool includeInDefault = true) {
        CurrentBlock = header;
        header.IncludeInDefault = includeInDefault;
    }

    public void EndBlock() {
        if (CurrentBlock == null)
            return;
        CurrentBlock.Length = template.Length - CurrentBlock.Start;
        if (CurrentBlock != header && CurrentBlock != footer)
            files.Add(CurrentBlock);
        currentBlock = null;
    }

    public virtual void Process(bool split, bool sync = true) {
        if (split) {
            EndBlock();
            String headerText = template.ToString(header.Start, header.Length);
            String footerText = template.ToString(footer.Start, footer.Length);
            String outputPath = Path.GetDirectoryName(host.TemplateFile);
            files.Reverse();
            if (!footer.IncludeInDefault)
                template.Remove(footer.Start, footer.Length);
            foreach(Block block in files) {
                String fileName = Path.Combine(outputPath, block.Name);
                String content = headerText + template.ToString(block.Start, block.Length) + footerText;
                generatedFileNames.Add(fileName);
                CreateFile(fileName, content);
                template.Remove(block.Start, block.Length);
            }
            if (!header.IncludeInDefault)
                template.Remove(header.Start, header.Length);
        }
    }

    protected virtual void CreateFile(String fileName, String content) {
        if (IsFileContentDifferent(fileName, content))
            File.WriteAllText(fileName, content);
    }

    public virtual String GetCustomToolNamespace(String fileName) {
        return null;
    }

    public virtual String DefaultProjectNamespace {
        get { return null; }
    }

    protected bool IsFileContentDifferent(String fileName, String newContent) {
        return !(File.Exists(fileName) && File.ReadAllText(fileName) == newContent);
    }

    private Manager(ITextTemplatingEngineHost host, StringBuilder template) {
        this.host = host;
        this.template = template;
    }

    private Block CurrentBlock {
        get { return currentBlock; }
        set {
            if (CurrentBlock != null)
                EndBlock();
            if (value != null)
                value.Start = template.Length;
            currentBlock = value;
        }
    }

    private class VSManager: Manager {
        private EnvDTE.ProjectItem templateProjectItem;
        private EnvDTE.DTE dte;
        private Action<String> checkOutAction;
        private Action<IEnumerable<String>> projectSyncAction;

        public override String DefaultProjectNamespace {
            get {
                return templateProjectItem.ContainingProject.Properties.Item("DefaultNamespace").Value.ToString();
            }
        }

        public override String GetCustomToolNamespace(string fileName) {
            return dte.Solution.FindProjectItem(fileName).Properties.Item("CustomToolNamespace").Value.ToString();
        }

        public override void Process(bool split, bool sync) {
            if (templateProjectItem.ProjectItems == null)
                return;
            base.Process(split, sync);
            if (sync)
                projectSyncAction.EndInvoke(projectSyncAction.BeginInvoke(generatedFileNames, null, null));
        }

        protected override void CreateFile(String fileName, String content) {
            if (IsFileContentDifferent(fileName, content)) {
                CheckoutFileIfRequired(fileName);
                File.WriteAllText(fileName, content);
            }
        }

        internal VSManager(ITextTemplatingEngineHost host, StringBuilder template)
            : base(host, template) {
            var hostServiceProvider = (IServiceProvider) host;
            if (hostServiceProvider == null)
                throw new ArgumentNullException("Could not obtain IServiceProvider");
            dte = (EnvDTE.DTE) hostServiceProvider.GetService(typeof(EnvDTE.DTE));
            if (dte == null)
                throw new ArgumentNullException("Could not obtain DTE from host");
            templateProjectItem = dte.Solution.FindProjectItem(host.TemplateFile);
            checkOutAction = (String fileName) => dte.SourceControl.CheckOutItem(fileName);
            projectSyncAction = (IEnumerable<String> keepFileNames) => ProjectSync(templateProjectItem, keepFileNames);
        }

        private static void ProjectSync(EnvDTE.ProjectItem templateProjectItem, IEnumerable<String> keepFileNames) {
            var keepFileNameSet = new HashSet<String>(keepFileNames);
            var projectFiles = new Dictionary<String, EnvDTE.ProjectItem>();
            var originalFilePrefix = Path.GetFileNameWithoutExtension(templateProjectItem.get_FileNames(0)) + ".";
            foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems)
                projectFiles.Add(projectItem.get_FileNames(0), projectItem);

            // Remove unused items from the project
            foreach(var pair in projectFiles)
                if (!keepFileNames.Contains(pair.Key) && !(Path.GetFileNameWithoutExtension(pair.Key) + ".").StartsWith(originalFilePrefix))
                    pair.Value.Delete();

            // Add missing files to the project
            foreach(String fileName in keepFileNameSet)
                if (!projectFiles.ContainsKey(fileName))
                    templateProjectItem.ProjectItems.AddFromFile(fileName);
        }

        private void CheckoutFileIfRequired(String fileName) {
            var sc = dte.SourceControl;
            if (sc != null && sc.IsItemUnderSCC(fileName) && !sc.IsItemCheckedOut(fileName))
                checkOutAction.EndInvoke(checkOutAction.BeginInvoke(fileName, null, null));
        }
    }
} #>

  1 <#@ template language="C#" debug="True" hostspecific="True" #>
  2 <#@ assembly name="System.Core"
  3 #><#@ assembly name="EnvDTE"
  4 #><#@ assembly name="System.Xml"
  5 #><#@ assembly name="System.Xml.Linq"
  6 #><#@ assembly name="System.Configuration" #>
  7 <#@ import namespace="System"
  8 #><#@ import namespace="System.CodeDom"
  9 #><#@ import namespace="System.CodeDom.Compiler"
 10 #><#@ import namespace="System.Collections.Generic"
 11 #><#@ import namespace="System.IO"
 12 #><#@ import namespace="System.Linq"
 13 #><#@ import namespace="System.Reflection"
 14 #><#@ import namespace="System.Text"
 15 #><#@ import namespace="System.Xml.Linq"
 16 #><#@ import namespace="Microsoft.VisualStudio.TextTemplating"
 17 #><#@ import namespace="System.Configuration" #>
 18 <#+
 19     public ConnectionStringSettings GetConnectionStringSettings(string connectionStringName){
 20         if (string.IsNullOrEmpty(connectionStringName))
 21             throw new ArgumentNullException("connectionStringName");
 22         var configFile = new ExeConfigurationFileMap();
 23         configFile.ExeConfigFilename = GetConfigPath();
 24         if (string.IsNullOrEmpty(configFile.ExeConfigFilename))
 25             throw new ArgumentNullException("The project does not contain App.config or Web.config file.");
 26         var config = System.Configuration.ConfigurationManager.OpenMappedExeConfiguration(configFile, ConfigurationUserLevel.None);
 27         var connSection = config.ConnectionStrings;
 28         var connectionStringSettings = connSection.ConnectionStrings[connectionStringName];
 29         if(connectionStringSettings == null)
 30             throw new ArgumentNullException("connectionStringName not exists");
 31         return connectionStringSettings;
 32     }
 33     public string GetConfigPath(){
 34         EnvDTE.Project project = GetCurrentProject();
 35         foreach (EnvDTE.ProjectItem item in project.ProjectItems){
 36             if (item.Name.Equals("App.config", StringComparison.InvariantCultureIgnoreCase) || item.Name.Equals("Web.config", StringComparison.InvariantCultureIgnoreCase))
 37             return GetProjectPath() + "\\" + item.Name;
 38         }
 39         return String.Empty;
 40     }
 41     public string GetProjectPath(){
 42         EnvDTE.Project project = GetCurrentProject();
 43         System.IO.FileInfo info = new System.IO.FileInfo(project.FullName);
 44         return info.Directory.FullName;
 45     }
 46     public string GetDataDirectory(){
 47         EnvDTE.Project project = GetCurrentProject();
 48         return System.IO.Path.GetDirectoryName(project.FileName) + "\\App_Data\\";
 49     }
 50     
 51     public EnvDTE.Project GetCurrentProject(){
 52         IServiceProvider _ServiceProvider = (IServiceProvider)Host;
 53         if (_ServiceProvider == null)
 54             throw new Exception("Host property returned unexpected value (null)");
 55 
 56         EnvDTE.DTE dte = (EnvDTE.DTE)_ServiceProvider.GetService(typeof(EnvDTE.DTE));
 57         if (dte == null)
 58             throw new Exception("Unable to retrieve EnvDTE.DTE");
 59 
 60         Array activeSolutionProjects = (Array)dte.ActiveSolutionProjects;
 61         if (activeSolutionProjects == null)
 62             throw new Exception("DTE.ActiveSolutionProjects returned null");
 63 
 64         EnvDTE.Project dteProject = (EnvDTE.Project)activeSolutionProjects.GetValue(0);
 65         if (dteProject == null)
 66             throw new Exception("DTE.ActiveSolutionProjects[0] returned null");
 67 
 68         return dteProject;
 69 }
 70     // Manager class records the various blocks so it can split them up
 71 class Manager {
 72     private class Block {
 73         public String Name;
 74         public int Start, Length;
 75         public bool IncludeInDefault;
 76     }
 77 
 78     private Block currentBlock;
 79     private List<Block> files = new List<Block>();
 80     private Block footer = new Block();
 81     private Block header = new Block();
 82     private ITextTemplatingEngineHost host;
 83     private StringBuilder template;
 84     protected List<String> generatedFileNames = new List<String>();
 85 
 86     public static Manager Create(ITextTemplatingEngineHost host, StringBuilder template) {
 87         return (host is IServiceProvider) ? new VSManager(host, template) : new Manager(host, template);
 88     }
 89 
 90     public void StartNewFile(String name) {
 91         if (name == null)
 92             throw new ArgumentNullException("name");
 93         CurrentBlock = new Block { Name = name };
 94     }
 95 
 96     public void StartFooter(bool includeInDefault = true) {
 97         CurrentBlock = footer;
 98         footer.IncludeInDefault = includeInDefault;
 99     }
100 
101     public void StartHeader(bool includeInDefault = true) {
102         CurrentBlock = header;
103         header.IncludeInDefault = includeInDefault;
104     }
105 
106     public void EndBlock() {
107         if (CurrentBlock == null)
108             return;
109         CurrentBlock.Length = template.Length - CurrentBlock.Start;
110         if (CurrentBlock != header && CurrentBlock != footer)
111             files.Add(CurrentBlock);
112         currentBlock = null;
113     }
114 
115     public virtual void Process(bool split, bool sync = true) {
116         if (split) {
117             EndBlock();
118             String headerText = template.ToString(header.Start, header.Length);
119             String footerText = template.ToString(footer.Start, footer.Length);
120             String outputPath = Path.GetDirectoryName(host.TemplateFile);
121             files.Reverse();
122             if (!footer.IncludeInDefault)
123                 template.Remove(footer.Start, footer.Length);
124             foreach(Block block in files) {
125                 String fileName = Path.Combine(outputPath, block.Name);
126                 String content = headerText + template.ToString(block.Start, block.Length) + footerText;
127                 generatedFileNames.Add(fileName);
128                 CreateFile(fileName, content);
129                 template.Remove(block.Start, block.Length);
130             }
131             if (!header.IncludeInDefault)
132                 template.Remove(header.Start, header.Length);
133         }
134     }
135 
136     protected virtual void CreateFile(String fileName, String content) {
137         if (IsFileContentDifferent(fileName, content))
138             File.WriteAllText(fileName, content);
139     }
140 
141     public virtual String GetCustomToolNamespace(String fileName) {
142         return null;
143     }
144 
145     public virtual String DefaultProjectNamespace {
146         get { return null; }
147     }
148 
149     protected bool IsFileContentDifferent(String fileName, String newContent) {
150         return !(File.Exists(fileName) && File.ReadAllText(fileName) == newContent);
151     }
152 
153     private Manager(ITextTemplatingEngineHost host, StringBuilder template) {
154         this.host = host;
155         this.template = template;
156     }
157 
158     private Block CurrentBlock {
159         get { return currentBlock; }
160         set {
161             if (CurrentBlock != null)
162                 EndBlock();
163             if (value != null)
164                 value.Start = template.Length;
165             currentBlock = value;
166         }
167     }
168 
169     private class VSManager: Manager {
170         private EnvDTE.ProjectItem templateProjectItem;
171         private EnvDTE.DTE dte;
172         private Action<String> checkOutAction;
173         private Action<IEnumerable<String>> projectSyncAction;
174 
175         public override String DefaultProjectNamespace {
176             get {
177                 return templateProjectItem.ContainingProject.Properties.Item("DefaultNamespace").Value.ToString();
178             }
179         }
180 
181         public override String GetCustomToolNamespace(string fileName) {
182             return dte.Solution.FindProjectItem(fileName).Properties.Item("CustomToolNamespace").Value.ToString();
183         }
184 
185         public override void Process(bool split, bool sync) {
186             if (templateProjectItem.ProjectItems == null)
187                 return;
188             base.Process(split, sync);
189             if (sync)
190                 projectSyncAction.EndInvoke(projectSyncAction.BeginInvoke(generatedFileNames, null, null));
191         }
192 
193         protected override void CreateFile(String fileName, String content) {
194             if (IsFileContentDifferent(fileName, content)) {
195                 CheckoutFileIfRequired(fileName);
196                 File.WriteAllText(fileName, content);
197             }
198         }
199 
200         internal VSManager(ITextTemplatingEngineHost host, StringBuilder template)
201             : base(host, template) {
202             var hostServiceProvider = (IServiceProvider) host;
203             if (hostServiceProvider == null)
204                 throw new ArgumentNullException("Could not obtain IServiceProvider");
205             dte = (EnvDTE.DTE) hostServiceProvider.GetService(typeof(EnvDTE.DTE));
206             if (dte == null)
207                 throw new ArgumentNullException("Could not obtain DTE from host");
208             templateProjectItem = dte.Solution.FindProjectItem(host.TemplateFile);
209             checkOutAction = (String fileName) => dte.SourceControl.CheckOutItem(fileName);
210             projectSyncAction = (IEnumerable<String> keepFileNames) => ProjectSync(templateProjectItem, keepFileNames);
211         }
212 
213         private static void ProjectSync(EnvDTE.ProjectItem templateProjectItem, IEnumerable<String> keepFileNames) {
214             var keepFileNameSet = new HashSet<String>(keepFileNames);
215             var projectFiles = new Dictionary<String, EnvDTE.ProjectItem>();
216             var originalFilePrefix = Path.GetFileNameWithoutExtension(templateProjectItem.get_FileNames(0)) + ".";
217             foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems)
218                 projectFiles.Add(projectItem.get_FileNames(0), projectItem);
219 
220             // Remove unused items from the project
221             foreach(var pair in projectFiles)
222                 if (!keepFileNames.Contains(pair.Key) && !(Path.GetFileNameWithoutExtension(pair.Key) + ".").StartsWith(originalFilePrefix))
223                     pair.Value.Delete();
224 
225             // Add missing files to the project
226             foreach(String fileName in keepFileNameSet)
227                 if (!projectFiles.ContainsKey(fileName))
228                     templateProjectItem.ProjectItems.AddFromFile(fileName);
229         }
230 
231         private void CheckoutFileIfRequired(String fileName) {
232             var sc = dte.SourceControl;
233             if (sc != null && sc.IsItemUnderSCC(fileName) && !sc.IsItemCheckedOut(fileName))
234                 checkOutAction.EndInvoke(checkOutAction.BeginInvoke(fileName, null, null));
235         }
236     }
237 } #>

添加T4文件:NorthwindContext.tt

View Code

<#@ template debug="True" hostspecific="True" language="C#" #>
<#@ Include File="MultipleOutputHelper.ttinclude" #>
<#@ Assembly Name="$(TargetDir)NLite.dll" #>
<#@ Assembly Name="$(TargetDir)ELinq.dll" #>
<#@ Assembly Name="System.Data" #>
<#@ Import Namespace="NLite.Data" #>
<#@ Import Namespace="NLite.Data.CodeGeneration" #>
<#@ output extension=".cs" #>
<#
    var @namespace = "NLite.Data.CodeGenerationDemo";
    var connectionStringName = "Northwind";
    var dbContextName = Host.TemplateFile.Split('\\')[Host.TemplateFile.Split('\\').Length - 1].TrimEnd('.', 't');
    var connectionStringSetting = GetConnectionStringSettings(connectionStringName);
    var connectionString = connectionStringSetting.ConnectionString;
    var dbProviderName = connectionStringSetting.ProviderName;
    var dbConfiguration = DbConfiguration.Configure(connectionString, dbProviderName);
    var databaseSchema = dbConfiguration.Schema;
    var manager = Manager.Create(Host, GenerationEnvironment);
    manager.StartHeader();
#>
using System;
using System.Collections.Generic;
using System.Linq;
using NLite.Data;
namespace <#= @namespace #>
{
<#
    manager.EndBlock();
#>
    using NLite.Reflection;

    public partial class <#= dbContextName #>:DbContext
    {
        //连接字符串名称：基于Config文件中连接字符串的配置
        const string connectionStringName = "<#= connectionStringName #>";

        //构造dbConfiguration 对象
        static DbConfiguration dbConfiguration;

        static <#= dbContextName #>()
        {
             dbConfiguration = DbConfiguration
                  .Configure(connectionStringName)
                  .SetSqlLogger(() =>SqlLog.Debug)
                  .AddFromAssemblyOf<<#= dbContextName #>>(t=>t.HasAttribute<TableAttribute>(false))
                  ;
        }

        public <#= dbContextName #>():base(dbConfiguration){}
        
<#foreach (var tb in databaseSchema.Tables.Union(databaseSchema.Views)){#>
        public IDbSet<<#=NamingConversion.Default.ClassName(tb.TableName)  #>> <#= NamingConversion.Default.QueryableName(tb.TableName) #> { get; private set; }
<#}#>
    }
<#foreach (var tb in databaseSchema.Tables){
        manager.StartNewFile(NamingConversion.Default.ClassName(tb.TableName) + ".generated.cs");#>
    [Table("<#= tb.TableName #>")]
    public partial class <#= NamingConversion.Default.ClassName( tb.TableName) #> 
    {
<#foreach (var col in tb.PrimaryKeys){#>    
        [Id("<#= col.ColumnName#>",IsDbGenerated=<#= col.IsGenerated.ToString().ToLower() #>)]
        public <#= NamingConversion.Default.DataType(col) #> <#= NamingConversion.Default.PropertyName(col.ColumnName) #> { get;set; }
<#}#> 
<#foreach (var col in tb.Columns){#>
        [Column("<#= col.ColumnName#>")]
        public <#= NamingConversion.Default.DataType(col) #> <#= NamingConversion.Default.PropertyName(col.ColumnName) #> { get;set; }
<#}#> 
<#foreach (var fk in tb.ForeignKeys){#>
        [ManyToOne(ThisKey="<#= NamingConversion.Default.PropertyName( fk.ThisKey.ColumnName) #>",OtherKey="<#= NamingConversion.Default.PropertyName(fk.OtherKey.ColumnName) #>")]
        public <#= NamingConversion.Default.ClassName(fk.OtherTable.TableName) #> <#= NamingConversion.Default.ManyToOneName(fk) #> { get;set; }
<#}#> 
<#foreach (var fk in tb.Children){#>
        [OneToMany(ThisKey="<#= NamingConversion.Default.PropertyName( fk.ThisKey.ColumnName) #>",OtherKey="<#= NamingConversion.Default.PropertyName(fk.OtherKey.ColumnName) #>")]
        public IList<<#= NamingConversion.Default.ClassName(fk.OtherTable.TableName) #>> <#= NamingConversion.Default.QueryableName(fk.OtherTable.TableName) #> { get;set; }
<#}#> 
    }
<# } manager.EndBlock();
 foreach (var tb in databaseSchema.Views){
     manager.StartNewFile(NamingConversion.Default.ClassName(tb.TableName) + ".generated.cs");#>
    [Table("<#= tb.TableName #>",Readonly=true)]
    public partial class <#= NamingConversion.Default.ClassName( tb.TableName) #> 
    {
<#foreach (var col in tb.Columns){#>
        [Column("<#= col.ColumnName#>")]
        public <#= col.Type.Name #> <#= NamingConversion.Default.PropertyName(col.ColumnName) #> { get;set; }
<#}#> 
    }
<# 
    } manager.EndBlock();
    manager.StartFooter();
#>
}
<#
 manager.EndBlock();
 manager.Process(true);
#>

保存一下NorthwindContext.tt 文件，系统会自动创建实体、实体间的关系（一对多，多对一)和DbContext，见下图

　　8. 运行代码查看

补充

　　1. ELinq 数据库Schema元数据结构图（只要配置好了DbConfiguration对象，只需要调用其Schema属性就会自动得到如下Schema数据

2. ELinq 还提供了表名到类名、列名到属性等转换约定，针对特殊情况可以自行定制

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NLite.Data.Schema;

namespace NLite.Data.CodeGeneration
{

     /// <summary>
    /// 命名约定
    /// </summary>
    public static class NamingConversion
    {
        /// <summary>
        /// 缺省命名约定
        /// </summary>
        public static readonly INamingConversion Default = new DefaultNamingConversion();
    }

    /// <summary>
    /// 命名约定
    /// </summary>
    public interface INamingConversion
    {
        /// <summary>
        /// 表名转集合名
        /// </summary>
        /// <param name="tableName"></param>
        /// <returns></returns>
        string QueryableName(string tableName);
        /// <summary>
        /// 表名转类名
        /// </summary>
        /// <param name="tableName"></param>
        /// <returns></returns>
        string ClassName(string tableName);

        /// <summary>
        /// 列名转字段名
        /// </summary>
        /// <param name="columnName"></param>
        /// <returns></returns>
        string FieldName(string columnName);

        /// <summary>
        /// 列名属性名转
        /// </summary>
        /// <param name="columnName"></param>
        /// <returns></returns>
        string PropertyName(string columnName);

        /// <summary>
        /// 得到类的数据类型
        /// </summary>
        /// <param name="col"></param>
        /// <returns></returns>
        string DataType(IColumnSchema col);

        /// <summary>
        /// 得到外键对应的导航属性名称
        /// </summary>
        /// <param name="fk"></param>
        /// <returns></returns>
        string ManyToOneName(IForeignKeySchema fk);
    }
}

　　3. 默认情况下自定义DbContext名称和T4模版文件的名称一致

　　 4. 如何修该代码生成的命名空间以及数据库配置

总结

　　最后附上Demo代码，大家可以修改一下配置文件，即可支持其它数据库的代码生成，也可以修改T4 模版DIY 自己的代码生成器！随后会发布基于Nuget安装方式的T4 模版代码生成器包，供大家方便使用、

技术支持：

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新年伊始，祝大家春节愉快，万事如意，谢谢大家的阅读，麻烦大伙点一下推荐，再次谢谢大家。 ^_^

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原文地址：https://www.cnblogs.com/netcasewqs/p/2912838.html