C#泛型约束与接口解耦API
在编写数据访问层时,我希望将面向公共的API与具体的db实现分离。例如,假设我想使用MongoDb或Cassandra作为我的备份存储 所以,我想要的是我的C#代码通过一个工厂方法等来利用iTingDao。工厂将与实际实现相对应 我有一些非常基本的接口和类示例来演示我希望实现的功能。不幸的是,这段代码生成了大量编译时错误,表示类没有实现接口的成员 以下内容定义了我的数据对象:C#泛型约束与接口解耦API,c#,generics,C#,Generics,在编写数据访问层时,我希望将面向公共的API与具体的db实现分离。例如,假设我想使用MongoDb或Cassandra作为我的备份存储 所以,我想要的是我的C#代码通过一个工厂方法等来利用iTingDao。工厂将与实际实现相对应 我有一些非常基本的接口和类示例来演示我希望实现的功能。不幸的是,这段代码生成了大量编译时错误,表示类没有实现接口的成员 以下内容定义了我的数据对象: public interface IBase { Object Id { get; set; } Dat
public interface IBase
{
Object Id { get; set; }
DateTime CreatedDate { get; set; }
}
public interface IBaseMongoDb : IBase
{
// Common MongoDb related things used by all concrete implementations
}
public interface IBaseCassandra : IBase
{
// Common Cassandra related things used by all concrete implementations
}
public interface IThing : IBase
{
String Name { get; set; }
}
public abstract class AbstractBase
{
public virtual Object Id { get; set; }
public DateTime CreatedDate { get; set; }
}
public abstract class AbstractMongoDbBase : AbstractBase
{
[BsonId]
public override Object Id { get; set; }
// Other specific MongoDb stuff
}
public abstract class AbstractCassandraBase : AbstractBase
{
// Cassandra related stuff
}
public class ThingMongoDbImpl : AbstractMongoDbBase, IThing, IBaseMongoDb
{
public String Name { get; set; }
}
public class ThingCassandraImpl : AbstractCassandraBase, IThing, IBaseCassandra
{
public String Name { get; set; }
}
MongoDb和Cassandra数据对象有单独的基本抽象,因为每个实现都有一个特定于另一个的公共特性(如注释等)
以下是数据访问接口:
public interface IDao<T>
{
T Save( T a_Value );
void Update( T a_Value );
void Delete( T a_Value );
T Find( Object a_Key );
}
public interface IThingDao : IDao<IThing>
{
IThing FindByName( String a_Name );
}
公共接口IDao
{
T保存(T a_值);
无效更新(T a_值);
无效删除(T a_值);
找不到(对象a_键);
}
公共接口:IThingDao:IDao
{
i使用FindByName(字符串a_名称);
}
以下是MongoDb和Cassandra的实现:
public abstract class AbstractMongoDbDao<T> where T : IBaseMongoDb, new()
{
public T Save( T a_Value )
{
// Save
return a_Value;
}
public void Update( T a_Value )
{
// Update
}
public void Delete( T a_Value )
{
// Delete
}
public T Find( Object a_Key )
{
return new T();
}
}
public class ThingDaoMongoDbImpl : AbstractMongoDbDao<ThingMongoDbImpl>, IThingDao
{
public IThing FindByName( String a_Name )
{
// Do the lookup and return value
return new ThingMongoDbImpl();
}
}
public abstract class AbstractCassandraDao<T> where T : IBaseCassandra, new()
{
public T Save( T a_Value )
{
// Save
return a_Value;
}
public void Update( T a_Value )
{
// Update
}
public void Delete( T a_Value )
{
// Delete
}
public T Find( Object a_Key )
{
return new T();
}
}
public class ThingDaoCassandraImpl : AbstractCassandraDao<ThingCassandraImpl>, IThingDao
{
public IThing FindByName( String a_Name )
{
// Do the lookup and return value
return new ThingCassandraImpl();
}
}
公共抽象类AbstractMongoDbDao,其中T:IBaseMongoDb,new()
{
公共T保存(T a_值)
{
//拯救
返回一个_值;
}
公共无效更新(T a_值)
{
//更新
}
公共无效删除(T a_值)
{
//删除
}
公共找不到(对象a_键)
{
返回新的T();
}
}
公共类thingdaomgodbimpl:AbstractMongoDbDao,IThingDao
{
public-IThing-FindByName(字符串a_名称)
{
//执行查找并返回值
返回新的ThingMongoDbImpl();
}
}
公共抽象类AbstractCassandrado,其中T:IBaseCassandra,new()
{
公共T保存(T a_值)
{
//拯救
返回一个_值;
}
公共无效更新(T a_值)
{
//更新
}
公共无效删除(T a_值)
{
//删除
}
公共找不到(对象a_键)
{
返回新的T();
}
}
公共类ThingDaoCassandraImpl:AbstractCassandrado,IThingDao
{
public-IThing-FindByName(字符串a_名称)
{
//执行查找并返回值
返回新内容cassandraimpl();
}
}
对于此代码,ThingDaoMongoDbImpl和ThingDaoCassandraImpl生成以下编译时错误:
Error 1 'generics.decouple.ThingDaoMongoDbImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Find(object)'. 'generics.decouple.AbstractMongoDbDao<generics.decouple.ThingMongoDbImpl>.Find(object)' cannot implement 'generics.decouple.IDao<generics.decouple.IThing>.Find(object)' because it does not have the matching return type of 'generics.decouple.IThing'.
Error 2 'generics.decouple.ThingDaoMongoDbImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Delete(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 95 18 Z
Error 3 'generics.decouple.ThingDaoMongoDbImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Update(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 95 18 Z
Error 4 'generics.decouple.ThingDaoMongoDbImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Save(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 95 18 Z
Error 5 'generics.decouple.ThingDaoCassandraImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Find(object)'. 'generics.decouple.AbstractCassandraDao<generics.decouple.ThingCassandraImpl>.Find(object)' cannot implement 'generics.decouple.IDao<generics.decouple.IThing>.Find(object)' because it does not have the matching return type of 'generics.decouple.IThing'.
Error 6 'generics.decouple.ThingDaoCassandraImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Delete(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 126 18 Z
Error 7 'generics.decouple.ThingDaoCassandraImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Update(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 126 18 Z
Error 8 'generics.decouple.ThingDaoCassandraImpl' does not implement interface member 'generics.decouple.IDao<generics.decouple.IThing>.Save(generics.decouple.IThing)' C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\Generics.cs 126 18 Z
错误1“generics.decouple.ThingDaoMongoDbImpl”未实现接口成员“generics.decouple.IDao.Find(object)”。”generics.decouple.AbstractMongoDbDao.Find(对象)“无法实现”generics.decouple.IDao.Find(对象)”,因为它没有匹配的返回类型“generics.decouple.IThing”。
错误2“generics.decouple.ThingDaoMongoDbImpl”未实现接口成员“generics.decouple.IDao.Delete(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 95 18 Z
错误3“generics.decouple.ThingDaoMongoDbImpl”未实现接口成员“generics.decouple.IDao.Update(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 95 18 Z
错误4“generics.decouple.ThingDaoMongoDbImpl”未实现接口成员“generics.decouple.IDao.Save(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 95 18 Z
错误5“generics.decouple.ThingDaoCassandraImpl”未实现接口成员“generics.decouple.IDao.Find(object)”。”generics.decouple.AbstractCassandrado.Find(对象)“无法实现”generics.decouple.IDao.Find(对象)”,因为它没有匹配的返回类型“generics.decouple.IThing”。
错误6“generics.decouple.ThingDaoCassandraImpl”未实现接口成员“generics.decouple.IDao.Delete(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 126 18 Z
错误7“generics.decouple.ThingDaoCassandraImpl”未实现接口成员“generics.decouple.IDao.Update(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 126 18 Z
错误8“generics.decouple.ThingDaoCassandraImpl”未实现接口成员“generics.decouple.IDao.Save(generics.decouple.IThing)”C:\Projects\EDC\modules\EXCHANGES\CAD2CAD.Net\Z\generics.cs 126 18 Z
有什么建议可以让它工作吗
谢谢这里有很多似乎不正确的地方,这对于一个简单的答案来说可能太宽泛了。例如,在
AbstractMongoDbDao
类中,方法获取并返回参数T,该参数仅限于ibasMongoDB
。这就是你的意思吗?要保存并返回一个IBaseMongoDb
?或者您想要像公共TValue保存(TValue value){…}
?@RonBeyer谢谢您的回答。是的,我想用IBaseMongoDb进行约束,因为这些数据对象中有特定于MongoDb的东西,比如BSON注释。我看到了很多重复的代码IBase->IBaseMongoDb
和AbstractBase->AbstractMongoDbBase
都具有相同的属性,在ThingMongoDbImpl
中实现和描述。你不知道是什么让你这么做的吗?但这些重复是可以避免的。当你有抽象类时,也要避免在接口中使用属性。谢谢你的回答。这两个抽象道都有你所指的方法。这就是为什么我把它们放在抽象类中,所有其他子类都会自动获取它们。那不对吗?不,不对。查看我的更新。必须实现接口
public class ThingDaoMongoDbImpl : AbstractMongoDbDao<ThingMongoDbImpl>, IThingDao
{
public IThing FindByName( String a_Name )
{
// Do the lookup and return value
return new ThingMongoDbImpl();
}
T Save( T a_Value ) { //implement it
}
void Update( T a_Value ) {
//implement it here
}
void Delete( T a_Value ) { // implement it here}
T Find( Object a_Key ) { //implement it}
}
public class ThingCassandraImpl : AbstractCassandraBase, IThing, IBaseCassandra, IThingDao
{
public String Name { get; set; }
public IThing Save(IThing a_Value)
{
throw new NotImplementedException();
}
public void Update(IThing a_Value)
{
throw new NotImplementedException();
}
public void Delete(IThing a_Value)
{
throw new NotImplementedException();
}
public IThing Find(object a_Key)
{
throw new NotImplementedException();
}
public IThing FindByName(string a_Name)
{
throw new NotImplementedException();
}
}
public abstract class AbstractCassandraDao<T> where T : IBaseCassandra,IThingDao, new()
{
public T Save(T a_Value)
{
// Save
return a_Value;
}
public void Update(T a_Value)
{
// Update
}
public void Delete(T a_Value)
{
// Delete
}
public T Find(Object a_Key)
{
return new T();
}
}
public class ThingDaoCassandraImpl : AbstractCassandraDao<ThingCassandraImpl>
{
public IThing FindByName(String a_Name)
{
// Do the lookup and return value
return new ThingCassandraImpl();
}
public IThing Save(IThing a_Value)
{
throw new NotImplementedException();
}
public void Update(IThing a_Value)
{
throw new NotImplementedException();
}
public void Delete(IThing a_Value)
{
throw new NotImplementedException();
}
public IThing Find(object a_Key)
{
throw new NotImplementedException();
}
}