Help with abstract/override RSS

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  NoBullMan

  Participant

  1019 Points

  780 Posts

  Help with abstract/override

  Dec 04, 2012 08:40 PM|LINK

  Trying to learn C# using abstract, override, ..., data layers...

  I created a DAL and a BLL folder and added the classes but a running into some problems. This is what I have (just one file example):

  DAL\Agent.cs

  namespace DAL
  {
      public class Agent
      {
          public override int AddAgent(PLAgent newAgent)   <---- DAL.Agent.AddAgent(...): no suitable method found to override         {
              OracleCommand oraCmd = new OracleCommand();
              ....
              ExecuteOraNonQuery(oraCmd, this.ConnectionString);
          }
      }
  }

  DAL\AgentProvider.cs

  namespace DAL
  {
      public abstract class AgentProvider : DataAccess
      {
          public abstract int AddAgent(PLAgent newAgent);      }
  }

  BLL/AddAgent

  namespace BLL
  {
      public class PLAgent
      {
          public static int AddAgent(PLAgent newAgent)
          {           
              return Agent.AddAgent(newAgent);
          }
      }
  }
  

  Can you tell me why I get these errors?

  Thanks.

  • Edited by NoBullMan on Dec 04, 2012 08:41 PM
  • Edited by NoBullMan on Dec 04, 2012 09:10 PM
  • Edited by NoBullMan on Dec 04, 2012 09:10 PM
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  Careed

  All-Star

  18764 Points

  3637 Posts

  Re: Help with abstract/override

  Dec 04, 2012 09:22 PM|LINK

  In your Agent class, it is not inheriting from any other (except for System.Object), so you cannot override a method that doesn't have a method to override, i.e., a method for its hierarchy that has been marked as virtual.

  It would appear that the Agent class needs to inherit from the AgentProvider class, but I'm not completely certain.

  Christopher Reed, MCT, MCPD, MCTS, Microsoft Specialist, MTA
  "The oxen are slow, but the earth is patient."
• • Reply
  

  NoBullMan

  Participant

  1019 Points

  780 Posts

  Re: Help with abstract/override

  Dec 05, 2012 05:29 PM|LINK

  Thanks Careed. That got rid of the error but now I have a different problem which has to do with property/method access. This is a simplified version of two files in DAL and one in BLL folders:

  AgentProvider.cs in DAL:

  using BLL;
  
  namespace DAL
  {
      public abstract class AgentProvider : DataAccess
      {
  	public abstract int AddAgent(PLAgent newAgent);
  	....
      }
  }

  Agent.cs in DAL:

  using BLL;
  
  namespace DAL
  {
      public class Agent : AgentProvider
      {
  	public override int AddAgent(PLAgent newAgent)
  	{
  	    Oracle queries to add an agent to database
  	    can access "newAgent.AgentName"
          }
      }
  }

  Agent.cs in BLL:

  using DAL;
  
  namespace BLL
  {
      public class PLAgent
      {
          public int AgentID;
  	public string AgentName;
          ....
          public static int AddAgent(PLAgent newAgent)
  	{
  	    return Agent.AddAgent(newAgent); <----  Problem!
  	}
      }
  }
  Cannot access Agent.AddAgent method of DAL. When I type "Agent." intellisense just shows "Equals" and "referenceEqulas". Can only do PLAgent.AddAgent(newAgent) but it is just the same method I am already in!

   

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  NoBullMan

  Participant

  1019 Points

  780 Posts

  Re: Help with abstract/override

  Dec 05, 2012 06:27 PM|LINK

  I solved the access issue using the following method in AgentProvider.cs file. What I am not sure is if I have to do this for every xxxProvider.cs file (I have dozen or so) or if this can be made into a generic method:

  public static DataAccess GetDataAccess()
          {
              string dataAccessStringType = "DAL.AgentProvider";
              Type dataAccessType = Type.GetType(dataAccessStringType);
  
              if (dataAccessType == null)
              {
                  throw (new NullReferenceException("DataAccessType can not be found"));
              }
              Type tp = Type.GetType("DAL.AgentProvider");
  
              if (!tp.IsAssignableFrom(dataAccessType))
              {
                  throw (new ArgumentException("DataAccessType does not inherits from DAL.AgentProvider"));
              }
              DataAccess dc = (DataAccess)Activator.CreateInstance(dataAccessType);
              return (dc);
          }

   

  And then in Agent.cs (BLL folder):

  public static int AddAgent(PLAgent newAgent)
  {
      Agent DALLayer = Agent.GetDataAccess();
      return DALLayer.AddAgent();
  }
  

  
  
  

  • Marked as answer by Angie xu - MSFT on Dec 11, 2012 06:35 AM