我正在尝试为我的Entity Framework存储库创建一个非常通用的泛型存储库,该存储库具有基本的CRUD语句并使用接口。我先打了一个砖墙头,然后被打倒了。这是我的代码,使用实体框架模型在控制台应用程序中编写,其中包含一个名为Hurl的表。只需尝试通过其ID撤回对象。这是完整的应用程序代码。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using System.Linq.Expressions;
using System.Reflection;
using System.Data.Objects.DataClasses;
namespace GenericsPlay
{
class Program
{
static void Main(string[] args)
{
var hs = new HurlRepository(new hurladminEntity());
var hurl = hs.Load<Hurl>(h => h.Id == 1);
Console.Write(hurl.ShortUrl);
Console.ReadLine();
}
}
public interface IHurlRepository
{
T Load<T>(Expression<Func<T, bool>> expression);
}
public class HurlRepository : IHurlRepository, IDisposable
{
private ObjectContext _objectContext;
public HurlRepository(ObjectContext objectContext)
{
_objectContext = objectContext;
}
public ObjectContext ObjectContext
{
get
{
return _objectContext;
}
}
private Type GetBaseType(Type type)
{
Type baseType = type.BaseType;
if (baseType != null && baseType != typeof(EntityObject))
{
return GetBaseType(type.BaseType);
}
return type;
}
private bool HasBaseType(Type type, out Type baseType)
{
Type originalType = type.GetType();
baseType = GetBaseType(type);
return baseType != originalType;
}
public IQueryable<T> GetQuery<T>()
{
Type baseType;
if (HasBaseType(typeof(T), out baseType))
{
return this.ObjectContext.CreateQuery<T>("[" + baseType.Name.ToString() + "]").OfType<T>();
}
else
{
return this.ObjectContext.CreateQuery<T>("[" + typeof(T).Name.ToString() + "]");
}
}
public T Load<T>(Expression<Func<T, bool>> whereCondition)
{
return this.GetQuery<T>().Where(whereCondition).First();
}
public void Dispose()
{
if (_objectContext != null)
{
_objectContext.Dispose();
}
}
}
}
以下是我收到的错误:
System.Data.EntitySqlException was unhandled
Message="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly., near escaped identifier, line 3, column 1."
Source="System.Data.Entity"
Column=1
ErrorContext="escaped identifier"
ErrorDescription="'Hurl' could not be resolved in the current scope or context. Make sure that all referenced variables are in scope, that required schemas are loaded, and that namespaces are referenced correctly."
这是我试图从中提取此信息的地方。
http://blog.keithpatton.com/2008/05/29/Polymorphic+Repository+For+ADONet+Entity+Framework.aspx
答案 0 :(得分:7)
public IQueryable<T> GetQuery<T>()
{
Type baseType;
if (HasBaseType(typeof(T), out baseType))
{
return this.ObjectContext.CreateQuery<T>(String.Format("[{0}]", baseType.Name.ToString())).OfType<T>();
}
else
{
return this.ObjectContext.CreateQuery<T>(String.Format("[{0}]", typeof(T).Name.ToString()));
}
}
答案 1 :(得分:0)