Question

In my below code , I have a list of AccessId, that is store in tag of nodes of tree.
How can I checked nodes (or childnodes) that tag of them is in my list ?

List<AccessFieldSet> AccessList = new List<AccessFieldSet>();
private void GetRolesAccessData(Int32 RolesId)
{            
    C_RolesUsers Db = new C_RolesUsers();
    AccessList = Db.GetRolesAccessData(RolesId);
    foreach (AccessFieldSet Afs in AccessList)
    {
        foreach (TreeNode node in TreeRoles.Nodes)
        {
            if (node.Tag == Afs.AccessId.ToString())
            {
                //Check Node is true ?
            }
            GetTagChildren(node);
        }
    }
}

private void GetTagChildren(TreeNode Node)
{
    TreeNode ChNode = null;
    //TreeFieldSet nodeCat = (TreeFieldSet)Node.Tag;
    //Int32 nodeCat = (Int32)Node.Tag;
    foreach (AccessFieldSet Afs in AccessList)
    {
        if (Afs.AccessId.ToString() == Node.Tag)
        {
            //Check Node is true ?
            GetTagChildren(ChNode);
        }
    }
}

I edit my code to :

List<AccessFieldSet> AccessList = new List<AccessFieldSet>();
private void GetRolesAccessData(Int32 RolesId)
{            
    C_RolesUsers Db = new C_RolesUsers();
    AccessList = Db.GetRolesAccessData(RolesId);
    for (int i = 0; i < TreeRoles.Nodes.Count; i++)
    {
        CheckedSelectedNodes(i, TreeRoles.Nodes, AccessList);
    }
}

private void CheckedSelectedNodes(Int32 i, TreeNodeCollection nodes, List<AccessFieldSet> AccessList)
{
    TreeNode node = nodes[i];
    for (int j = 0; j < AccessList.Count; j++)
    {
        foreach (AccessFieldSet Afs in AccessList)
        {
            if ((int)node.Tag == Afs.AccessId)
            {
                node.Checked = true;
            }
        }
    }
}

With new code, I can checked nodes that node’s tag is in AccessList. How can I change code for ChildNodes(Childs of nodes)?

Answer 1

You can use recursion to do this quite elegantly.

List<AccessFieldSet> accessList = new List<AccessFieldSet>(); 

private void GetRolesAccessData(Int32 RolesId) 
{             
    C_RolesUsers Db = new C_RolesUsers(); 
    accessList = Db.GetRolesAccessData(RolesId);
    foreach (TreeNode node in TreeRoles.Nodes)
    {
        CheckNodeRecursively(node, accessList);
    } 
} 

private void CheckNodeRecursively(TreeNode node, List<AccessFieldSet> accessList) 
{
    // Note: You don't need the for loop through 'j'.
    foreach (AccessFieldSet afs in accessList) 
    { 
        if ((int)node.Tag == afs.AccessId) 
        { 
            node.Checked = true; 
        } 
    }
    foreach (TreeNode childNode in node.Nodes)
    {
        CheckNodeRecursively(childNode, accessList);
    }
} 

If you find yourself doing this sort of thing often, you can factor out the recursion into a utility method and use Action to just vary the “act-on-each-node” logic. For example:

public static void ActOnAllRecursively(this TreeNodeCollection nodes, Action<TreeNode> action)
{
    foreach (TreeNode node in nodes)
    {
        ActOnRecursively(node, action);
    }
}

public static void ActOnRecursively(this TreeNode node, Action<TreeNode> action)
{
    action(node);
    foreach (TreeNode node in node.Nodes)
    {
        ActOnRecursively(node);
    }
}

Then your code just looks like this:

List<AccessFieldSet> accessList = new List<AccessFieldSet>(); 

private void GetRolesAccessData(Int32 RolesId) 
{             
    C_RolesUsers Db = new C_RolesUsers(); 
    accessList = Db.GetRolesAccessData(RolesId);
    TreeRoles.Nodes.ActOnAllRecursively((node) =>
    {
        foreach (AccessFieldSet afs in accessList) 
        { 
            if ((int)node.Tag == afs.AccessId) 
            { 
                node.Checked = true; 
            } 
        } 
    });
}

And finally, you could go crazy with LINQ and write your app-specific code in a declarative style:

List<AccessFieldSet> accessList = new List<AccessFieldSet>(); 

private void GetRolesAccessData(Int32 RolesId) 
{             
    C_RolesUsers Db = new C_RolesUsers(); 
    accessList = Db.GetRolesAccessData(RolesId);
    TreeRoles.Nodes.ActOnAllRecursively((node) =>
    {
        node.Checked = accessList.Any(afs => afs.AccessId == (int)node.Tag);
    });
}