Pass SqlDataReader As Parameter

Question

I'm with the follow question: I have a method that returns a SqlDataReader, then I do a While in this SqlDataReader as you see bellow:

using (SqlDataReader objSqlDtReader = objDtAccess.GetDataReader()) 
{
    while(objSqlDtReader.Read()) 
    {
           UserEntitie objUserEntitie = new UserEntitie();
           objUserEntitie.Name = Convert.ToString(objSqlDtReader["name"])    
    }
}

So, I need to fill all my UserEntite with all data, Name, Email, Id. But I have many methods in User Class as (GetUserById, GetUserByEmai, GetAllUsers), and I have to fill a data again.

I need to create an private method that fill my UserEntitie and in each method I only call my method FillUser and return its. I think that I need to pass my SqlDataReader to my private method FillUser.

Any suggestions to do this?

Cant get where is the problem. You already decided what to do. — Renatas M.
– Renatas M., Commented May 30, 2012 at 12:27

akatakritos · Accepted Answer · 2012-05-30 12:25:50Z

2

You could do something like this:

class UserEntitie
{
    internal void FillFromSqlDataReader(SqlDataReader reader)
    {
        this.Name = Convert.ToString(reader["name"]);
        /* Fill your fields */
    }
}

Usage:

using (SqlDataReader objSqlDtReader = objDtAccess.GetDataReader()) 
{
    while(objSqlDtReader.Read()) 
    {
        UserEntitie objUserEntitie = new UserEntitie();
        objUserEntitie.FillFromSqlDataReader(objSqlDtReader);
        /* Add to a list or something */    
    }
}

answered May 30, 2012 at 12:25

akatakritos

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Comments

inksmithy · Accepted Answer · 2012-05-30 12:32:43Z

I'm using a similar sort of system, but instead of passing the SqlDataReader into the private object, I instead pass a SqlConnection into the object and have a private FillDetailsFromDb() method which performs the necessary work.

So, instead of passing an SqlDataReader, I'll have a parameterless constructor as well as a constructor which takes a SqlConnection as a parameter.

When I have created the object, I'll pass a parameter (in my case its a Guid) into the object and my private method uses the SqlConnection it was constructed with along with a fresh SqlCommand which takes the parameter I sent to the public method.

    private void FillDetailsFromDb(Guid p)
    {
        SqlCommand com = new SqlCommand();
        com.Connection = conn;

        com.CommandText = "spSelectProspectUsingLinkParameter";
        com.CommandType = CommandType.StoredProcedure;
        com.Parameters.AddWithValue("@linkparam", p);
        conn.Open();
        SqlDataReader rdr = com.ExecuteReader();
        ...
        etc
    }

This means the object can still exist as a discrete object and can be used in other places and the SqlDataReader doesn't have to be passed around, which I've found it doesn't like very much.

Incidentally, while I was exploring this problem myself, I found there was a good chance I would strike weird null values in translating the data from the datatypes in the database to the .Net datatypes. Using something like the following code, I managed to avoid the DBNull datatypes as well as utilise the column names in the database.

if (!rdr.IsDBNull(rdr.GetOrdinal("firstname")))
{
    Firstname = rdr.GetString(rdr.GetOrdinal("firstname"));
}

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