How do I display non-normalized data in a hierarchical structure?

Question

My issue is that I want to display data in a hierarchal structure as so:

• Democrat
  
  • County Clerk
    • Candidate 1
    • Candidate 2

Answer 1

If you can modify the stored procedure, I would recommend a result set in the form of an adjacency list:

ID    Name          ParentID
1     Democrat      NULL
2     County Clerk  1
3     Magistrate    1
4     Candidate 1   2
5     Candidate 2   2
6     Candidate 1   3
7     Candidate 2   3
8     Candidate 3   3

It reduces the amount of data retrieved, and allows you to program recursively against the parent-child relationships. You simply start at the root. This approach avoids the hassle of using nested Repeaters by directly building the string literal in a StringBuilder.

StringBuilder sb = new StringBuilder();
DataTable dt = new DataTable();
someDataAdapter.Fill(dt);

// find the roots:
DataRow[] roots = dt.Select("parentId is null");

sb.Append("
");
foreach (DataRow child in roots)
{
    WriteNode(child, sb);
}
sb.Append("
");


// recursively write out each node
public static void WriteNode(DataRow row, StringBuilder sb) {
    sb.Append("
"); 
    sb.Append(row["Name"]);

    // find children rows...
    DataRow[] children = row.Table.Select("parentId = " + row["id"].ToString());
        if (children.Length > 0)
        {
            sb.Append("
");
            foreach (DataRow child in children)
            {
                WriteNode(child, sb);
            }
            sb.Append("
");
        }

        sb.Append("
");
    }