Entity Framework 的存储库和工作单元 T4 模板

引言

两周前，我写了重新审视实体框架中的仓库和工作单元模式这篇文章。 我觉得如果能有一个自动代码生成器来帮助我构建这些模式，而无需费力，那就太好了。 所以我坐下来创建了一个T4 模板，以自动生成我在文章中展示的相同模式。

代码

需要理解的一点是，提供的T4 模板并非万无一失，可能会出现错误（您可以根据需要更改实现）。 为了使用它，请将代码复制并粘贴到需要位于您的实体数据模型文件库中的.tt 文件中（T4 会在当前目录中搜索edmx 文件以自动生成类）。 另一种选择是从这里下载T4 模板。
这就是它

<#@ template debug="true" hostspecific="true" language="C#" #>
<#@ include file="EF.Utility.CS.ttinclude"#>
<#@ import namespace="System.IO" #>
<#@ output extension=".cs" #>
<#         
if(Errors.HasErrors)
{
    return String.Empty;
}

CodeGenerationTools code = new CodeGenerationTools(this)
	{FullyQualifySystemTypes = true, CamelCaseFields = false};
MetadataLoader loader = new MetadataLoader(this);

string open = "<";
string close = ">";
string SourceCsdlPath = FindEDMXFileName();
ReferenceCsdlPaths = new string[] {};
string namespaceName = code.VsNamespaceSuggestion();
ItemCollection = loader.CreateEdmItemCollection
	(SourceCsdlPath, ReferenceCsdlPaths.ToArray());
EntityContainer container = ItemCollection.GetItems<EntityContainer>().FirstOrDefault();
#>
using System;
using System.Collections.Generic;
using System.Data.Objects;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
 
namespace <#=namespaceName#>
{
    public interface IRepository<T> where T : class
    {    
        #region    Methods
    
        T GetById(int id);
        IEnumerable<T> GetAll();
        IEnumerable<T> Query(Expression<Func<T, bool>> filter);        
        void Add(T entity);
        void Remove(T entity);   
        
        #endregion
    }
    
    public abstract class Repository<T> : IRepository<T>
                                  where T : class
    {
        #region Members
 
        protected IObjectSet<T> _objectSet;
 
        #endregion
 
        #region Ctor
 
        public Repository(ObjectContext context)
        {
              _objectSet = context.CreateObjectSet<T>();
        }

        #endregion
 
        #region IRepository<T> Members
 
        public IEnumerable<T> GetAll()
        {
              return _objectSet;
        }
 
        public abstract T GetById(int id);
 
        public IEnumerable<T> Query(Expression<Func<T, bool>> filter)
        {
              return _objectSet.Where(filter);
        }
 
        public void Add(T entity)
        {
              _objectSet.AddObject(entity);
        }
 
        public void Remove(T entity)
        {
              _objectSet.DeleteObject(entity);
        }
 
        #endregion
      }
 
<#
    foreach (EntityType entity in 
	ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
    {        
#>
    
    public partial class <#= entity.Name #>Repository : 
		Repository<#=open#><#=entity.Name#><#=close#>
    {
        #region Ctor
 
        public <#= entity.Name #>Repository(ObjectContext context)
               : base(context)
        {
        }
 
        #endregion
 
        #region Methods
 
        public override <#= entity.Name #> GetById(int id)   
        {
            return _objectSet.SingleOrDefault(e => e.<#= 
		entity.KeyMembers.First().Name #> == id);
        }
 
        #endregion        
    }
<# 
    }        
#>
        
  public interface IUnitOfWork
  {
      #region    Methods
    
    <#
        foreach (EntitySet set in container.BaseEntitySets.OfType<EntitySet>())
        {    
    #>
        IRepository<#= open #><#= set.ElementType.Name #><#= close #> 
		<#= set.Name #> { get; }   
    <# 
        }
    #>
    void Commit();
    
    #endregion
  }
 
  public partial class UnitOfWork : IUnitOfWork
  {
    #region Members
 
    private readonly ObjectContext _context;
    <#
        foreach (EntitySet set in container.BaseEntitySets.OfType<EntitySet>())
        {    
    #>
    private <#= set.ElementType.Name #>Repository _<#= set.Name.ToLower() #>;
    <# 
        }
    #>    
    #endregion
 
    #region Ctor
 
    public UnitOfWork(ObjectContext context)
    {
      if (context == null)
      {
        throw new ArgumentNullException("context wasn't supplied");
      }
 
      _context = context;
    }
 
    #endregion
 
    #region IUnitOfWork Members
 
    <#
        foreach (EntitySet set in container.BaseEntitySets.OfType<EntitySet>())
        {    
    #>
    public IRepository<#= open #><#= set.ElementType.Name #><#= close #> <#= set.Name #>
    {
        get
        {
            if (_<#= set.Name.ToLower() #> == null)
            {
                _<#= set.Name.ToLower() #> = new <#= 
		set.ElementType.Name #>Repository(_context);
            }
            return _<#= set.Name.ToLower() #>;
        }
    }
    <# 
        }
    #>    
    
    public void Commit()
    {
      _context.SaveChanges();
    }
 
    #endregion
  }
}
<#+
public string SourceCsdlPath{ get; set; }
public EdmItemCollection ItemCollection{ get; set; }
public IEnumerable<string> ReferenceCsdlPaths{ get; set; }
 
string FindEDMXFileName()
{            
    string[] entityFrameworkFiles = Directory.GetFiles
		(Host.ResolvePath(string.Empty), "*.edmx");
    if(entityFrameworkFiles.Length > 0)
    {
        return entityFrameworkFiles[0];
    }
    
    return string.Empty;
}
#>

这是我在我的测试edmx 文件上运行T4 模板后生成的代码

using System;
using System.Collections.Generic;
using System.Data.Objects;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
 
namespace ConsoleApplication1
{
    public interface IRepository<T> where T : class
    {    
        #region    Methods
    
        T GetById(int id);
        IEnumerable<T> GetAll();
        IEnumerable<T> Query(Expression<Func<T, bool>> filter);        
        void Add(T entity);
        void Remove(T entity);   
        
        #endregion
    }
    
    public abstract class Repository<T> : IRepository<T>
                                  where T : class
    {
        #region Members
 
        protected IObjectSet<T> _objectSet;
 
        #endregion
 
        #region Ctor
 
        public Repository(ObjectContext context)
        {
              _objectSet = context.CreateObjectSet<T>();
        }
 
        #endregion
 
        #region IRepository<T> Members
 
        public IEnumerable<T> GetAll()
        {
              return _objectSet;
        }
 
        public abstract T GetById(int id);
 
        public IEnumerable<T> Query(Expression<Func<T, bool>> filter)
        {
              return _objectSet.Where(filter);
        }
 
        public void Add(T entity)
        {
              _objectSet.AddObject(entity);
        }
 
        public void Remove(T entity)
        {
              _objectSet.DeleteObject(entity);
        }
 
        #endregion
      }
 
    public partial class CourseRepository : Repository<Course>
    {
        #region Ctor

        public CourseRepository(ObjectContext context)
               : base(context)
        {
        }
 
        #endregion
 
        #region Methods
 
        public override Course GetById(int id)   
        {
            return _objectSet.SingleOrDefault(e => e.CourseID == id);
        }
 
        #endregion        
    }
    
    public partial class DepartmentRepository : Repository<Department>
    {
        #region Ctor
 
        public DepartmentRepository(ObjectContext context)
               : base(context)
        {
        }
 
        #endregion
 
        #region Methods
 
        public override Department GetById(int id)   
        {
            return _objectSet.SingleOrDefault(e => e.DepartmentID == id);
        }
 
        #endregion        
    }
    
    public partial class EnrollmentRepository : Repository<Enrollment>
    {
        #region Ctor
 
        public EnrollmentRepository(ObjectContext context)
               : base(context)
        {
        }
 
        #endregion
 
        #region Methods
 
        public override Enrollment GetById(int id)   
        {
            return _objectSet.SingleOrDefault(e => e.EnrollmentID == id);
        }
 
        #endregion        
    }
    
    public partial class PersonRepository : Repository<Person>
    {
        #region Ctor
 
        public PersonRepository(ObjectContext context)
               : base(context)
        {
        }
 
        #endregion
 
        #region Methods
 
        public override Person GetById(int id)   
        {
            return _objectSet.SingleOrDefault(e => e.PersonID == id);
        }
 
        #endregion        
    }
        
  public interface IUnitOfWork
  {
      #region    Methods
    
            IRepository<Course> Courses { get; }   
            IRepository<Department> Departments { get; }   
            IRepository<Enrollment> Enrollments { get; }   
            IRepository<Person> People { get; }   
        void Commit();
    
    #endregion
  }
 
  public partial class UnitOfWork
  {
    #region Members
 
    private readonly ObjectContext _context;
        private CourseRepository _courses;
        private DepartmentRepository _departments;
        private EnrollmentRepository _enrollments;
        private PersonRepository _people;
        
    #endregion
 
    #region Ctor
 
    public UnitOfWork(ObjectContext context)
    {
      if (context == null)
      {
        throw new ArgumentNullException("context wasn't supplied");
      }
 
      _context = context;
    }
 
    #endregion
 
    #region IUnitOfWork Members
 
        public IRepository<Course> Courses
    {
        get
        {
            if (_courses == null)
            {
                _courses = new CourseRepository(_context);
            }
            return _courses;
        }
    }
        public IRepository<Department> Departments
    {
        get
        {
            if (_departments == null)
            {
                _departments = new DepartmentRepository(_context);
            }
            return _departments;
        }
    }
        public IRepository<Enrollment> Enrollments
    {
        get
        {
            if (_enrollments == null)
            {
                _enrollments = new EnrollmentRepository(_context);
            }
            return _enrollments;
        }
    }
        public IRepository<Person> People
    {
        get
        {
            if (_people == null)
            {
                _people = new PersonRepository(_context);
            }
            return _people;
        }
    }
            
    public void Commit()
    {
      _context.SaveChanges();
    }
 
    #endregion
  }
}

尽情享用！