介紹

分層架構到這裡後，會發現有些地方明明是一樣的功能，卻還要重複編寫，像是CRUD這種功能，在這要說明如何將CRUD的部分抽離出來，使程式簡單化，不用寫重複的功能。

BaseModel

在SQLModel專案的Models資料夾下，新增BaseModel類別，裡面的內容是通常每個表都會使用的欄位，程式如下：

public abstract class BaseModel
{
	public DateTime CreateDate { get; set; }
	public DateTime ModifyDate { get; set; }

	public string CreatorId { get; set; }
	[ForeignKey("CreatorId")]
	public virtual ApplicationUser Creator { get; set; }
	
	public string ModifyId { get; set; }
	[ForeignKey("ModifyId")]
	public virtual ApplicationUser Modify { get; set; }
}

繼承BaseModel

在Project Model裡加入繼承BaseModel，在每次有新增Project的時候也會連BaseModel的內容一起新增，程式如下：

public class Project : BaseModel
{
	[Key]
	[Required]
	public Guid Id { get; set; }

	public string Name { get; set; }

	public virtual ICollection<Structure> Structure { get; set; }
}

Structure一樣也繼承BaseModel，記得要在下指令Add-Migration，再下Update-Database就新增好BaseModel了。

修改Repository

修改SQLModel專案的IRepository和GenericRepository，程式如下：

IRepository.cs 
public interface IRepository<TEntity>
{
	IUnitOfWork UnitOfWork { get; set; }

	Guid Create(TEntity entity);

	void Update(TEntity entity);

	Guid Delete(TEntity entity);

	IQueryable<TEntity> FindBy(Expression<Func<TEntity, bool>> predicate);

	IQueryable<TEntity> GetAll();

	TEntity GetById(Guid id);
}
GenericRepository.cs 
public class GenericRepository<TEntity> : IRepository<TEntity>
        where TEntity : BaseModel 
{
	public IDbSet<TEntity> DbSet { get; set; }
	public DbContext DbContext { get; set; }
	public IUnitOfWork UnitOfWork { get; set; }

	public GenericRepository(IUnitOfWork unitOfWork)
	{
		this.UnitOfWork = unitOfWork;
		this.DbContext = unitOfWork.Context;
		this.DbSet = DbContext.Set<TEntity>();
	}

	public virtual Guid Create(TEntity entity)
	{
		dynamic obj = DbSet.Add(entity);
		return obj.Id;
	}

	public void Update(TEntity entity)
	{
		DbSet.Attach(entity);
		DbContext.Entry(entity).State = EntityState.Modified;
		DbContext.Entry(entity).Property(x => x.CreateDate).IsModified = false;
		DbContext.Entry(entity).Property(x => x.CreatorId).IsModified = false;
	}

	public virtual Guid Delete(TEntity entity)
	{
		if (DbContext.Entry(entity).State == EntityState.Detached)
		{
			DbSet.Attach(entity);
		}
		dynamic obj = DbSet.Remove(entity);

		return obj.Id;
	}

	public virtual IQueryable<TEntity> FindBy(Expression<Func<TEntity, bool>> predicate)
	{
		return DbSet.Where(predicate);
	}

	public virtual IQueryable<TEntity> GetAll()
	{
		return DbSet;
	}

	public virtual TEntity GetById(Guid id)
	{
		return DbSet.Find(id);
	}
}

BaseService

在Service專案下，新增BaseService，在Nuget下載Microsoft.AspNet.WebApi.Client和Microsoft.AspNet.Identity.Core，Service會使用到這些參考，我們將BaseService利用泛型寫成可以傳入任何的Model，另外在這裡有用到IsNotEmptyOrNull是自己寫的一個StringHelper類別裡的方法，程式如下：

IBaseService.cs 
public interface IBaseService<TEntity>
{
	Guid Create(TEntity entity);
	bool Update(TEntity entity);
	bool UpdateOnly(TEntity entity);
	bool Delete(Guid id);
	IQueryable<TEntity> FindBy(Expression<Func<TEntity, bool>> predicate);
	IQueryable<TEntity> GetAll();
        TEntity GetById(Guid id);
}
BaseService.cs 
public abstract class BaseService<TEntity> : IBaseService<TEntity> where TEntity : BaseModel
{
	private readonly IUnitOfWork _unitOfWork;
	protected IRepository<TEntity> _repository { get; set; }

	public BaseService(IUnitOfWork unitOfWork, IRepository<TEntity> repository)
	{
		this._unitOfWork = unitOfWork;
		this._repository = repository;
	}

	public virtual Guid Create(TEntity entity)
	{
		string userId = HttpContext.Current.User.Identity.GetUserId();
		entity.CreatorId = entity.CreatorId.IsNotEmptyOrNull() ? entity.CreatorId : userId;
		entity.CreateDate = DateTime.Now;
		entity.ModifyId = userId;
		entity.ModifyDate = DateTime.Now;
		var result =  _repository.Create(entity);
		_repository.UnitOfWork.SaveChange();
		return result;
	}

	public virtual bool Update(TEntity entity)
	{
		bool result = false;
		if (null != entity)
		{
			entity.ModifyId = HttpContext.Current.User.Identity.GetUserId();
			entity.ModifyDate = DateTime.Now;
			_repository.Update(entity);
			_unitOfWork.SaveChange();
			result = true;
		}
		return result;
	}

	public virtual bool UpdateOnly(TEntity entity)
	{
		bool result = false;
		if (null != entity)
		{
			_repository.Update(entity);
			_unitOfWork.SaveChange();
			result = true;
		}
		return result;
	}

	public virtual bool Delete(Guid id)
	{
		var entity = _repository.GetById(id);
		var result = _repository.Delete(entity);
		_repository.UnitOfWork.SaveChange();
		return result == id;
	}

	public virtual IQueryable<TEntity> GetAll()
	{
		var result = _repository.GetAll();
		return result;
	}

	public virtual TEntity GetById(Guid id)
	{
		var result = _repository.GetById(id);
		return result;
	}

	public virtual IQueryable<TEntity> FindBy(Expression<Func<TEntity, bool>> predicate)
	{
		return _repository.FindBy(predicate);
	}
}
StringHelper.cs 
public static class StringHelper
{
	public static bool IsEmptyOrNull(this string input)
	{
		if (input == null || input.Equals(""))
		{
			return true;
		}
		else
		{
			return false;
		}
	}

	public static bool IsNotEmptyOrNull(this string input)
	{
		if (input == null || input.Equals(""))
		{
			return false;
		}
		else
		{
			return true;
		}
	}
}

修改ProjectService

接著要修改IProjectService和ProjectService，要繼承BaseService並在泛型裡加上使用的Model，繼承以後就不需要在每個Service寫CRUD這些重複的功能，程式如下：

IProjectService.cs 
public interface IProjectService : IBaseService<Project>
{        
}
ProjectService.cs 
public class ProjectService : BaseService<Project>, IProjectService
{
	public ProjectService(IUnitOfWork unitOfWork, IRepository<Project> repository)
		: base(unitOfWork, repository)
	{ }
}

StructureService就跟ProjectService差不多，去做修改就好了。都修改好之後，就可以執行了。到這裡會發現不用在每次新增新的Model後，在新的Service上還要寫CRUD這些功能了，只需要繼承BaseService就可以有這些功能，是不是方便很多！

程式碼已放上Github