将可以为两种不同类型的对象传递给C＃中的函数

Question

I want to have a function that receives either an sqlDataAdapter or a regular oleDataAdapter as on object parameter let's call it dbAdapter. I then want to use dbAdapter to access rows that are associated with whichever data adapter was passed to the function. Is this possible? I wanted to avoid passing a parameter to tell which one to use and then have an if statement with a set of almost identical code for each case. So, hypothetically, the function would be something like:

private void LoadRow(object dbAdapter, int theRow)
  {
     txtID.Text = dbAdapter.Rows[theRow]["ID"].ToString();

  }

and the call would look something like:

LoadRow(sqlDbAdapter, 1);

Or

LoadRow(oleDbAdapter, 1);

Where sqlDbAdapter is declared as an SqlDataAdapter and oleDbAdapter is declared as an OleDataAdapter.

I guess I could pass the function a value indicating which one to use and then an if statement to create which ever data adapter to use to the same variable name....like:

if (adapterType = "sql")
  {
     SqlDataAdapter dbAdapter = new SqlDataAdapter;
  }
else
  {
     OleDataAdapter dbAdapter = new OleDataAdapter;
  }

I think all the commands and other parameters of each adapter type are the same.... But I would like to pass the object by reference if that is possible...

Please give me your ideas and suggestions....

Thanks!

Valhalla

Answer 1

If you have to do it this way, I'd use extension methods:

public static string LoadRow(this SqlDataAdapter adapter, int theRow)
{
    //return something you need
}

public static string LoadRow(this OleDataAdapter adapter, int theRow)
{
    //return something you need
}

Usage would be like:

myOleDataAdapter.LoadRow(9);
mySqlDataAdapter.LoadRow(5;

Edit - To answer the critics, if IDbDataAdapter has everything in it that you need, you can do this instead because both of the adapters you are trying to use implement it.

public static string LoadRow(this IDbDataAdapter adapter, int theRow)
{
    //return something you need
}

Answer 2

A solution would be:

private void LoadRow(DbDataAdapter dbAdapter, int theRow){
    DataSet dataSet = new DataSet();
    dbAdapter.Fill(dataSet);
    txtID.Text = dataSet.Tables["myTable"].Rows[theRow]["ID"].ToString();
}

But use it carefully since the .Fill() method could result slow if used many times on a large data set. My advice is to fill the data set just once and use it as much as possible and then release it, or if it isn't meant to become too large, keep it in memory and refresh it when you think it's apportune.

Answer 3

一个简单的方法是重载该方法，只需两次创建它，一个对象是SqlDataAdapter，另一次将其创建为OleDataAdapter。