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Add TreeNodes dynamically

Posted on 2008-10-23
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Last Modified: 2013-12-17
I have a tree veiw with multiple levels, populated from a database.  The first level is the country the builds the car.

foreach (DataRow dr in concepts.Rows)
                    {
                        if (!treeView1.Nodes.ContainsKey(dr["country_id"].ToString()))
                        {
                            treeView1.Nodes.Add(dr["country_id"].ToString(), dr["country_name"].ToString());
                        }
                    }

//The second level is the make of the car

foreach (DataRow dr in concepts.Rows)
                    {
                        TreeNode[] nodes = treeView1.Nodes.Find(dr["country_id"].ToString(), true);
                        if (nodes.Length > 0)
                        {
                            TreeNode node = nodes[0];
                            if (!node.Nodes.ContainsKey(dr["make_id"].ToString()))
                            {
                                node.Nodes.Add(dr["make_id"].ToString(), dr["make_name"].ToString());
                            }
                        }
                    }

//The third level is the car dealership

foreach (DataRow dr in concepts.Rows)
                    {
                        TreeNode[] nodes = treeView1.Nodes.Find(dr["make_id"].ToString(), true);
                        if (nodes.Length > 0)
                        {
                            TreeNode node = nodes[0];
                            if (!node.Nodes.ContainsKey(dr["dealer_id"].ToString()))
                            {
                                node.Nodes.Add(dr["dealer_id"].ToString(), dr["year"].ToString());
                            }
                        }
                    }

//and the final level is the model

foreach (DataRow dr in concepts.Rows)
                    {
                        TreeNode[] nodes = treeView1.Nodes.Find(dr["dealer_id"].ToString(), true);
                        if (nodes.Length > 0)
                        {
                            TreeNode node = nodes[0];
                            if (!node.Nodes.ContainsKey(dr["dealer_id"].ToString()))
                            {
                                TreeNode newNode = new TreeNode();
                                newNode.Text = dr["model"].ToString();
                                node.Nodes.Add(newNode);
                            }
                        }
                    }

My problem is in the last two nodes.  No matter what dealer has the car,  all models are added to the first dealer in the tree.  I think it has to due with the schema of my database.  I have five tables.

1) country: PK countryID
2) make: PK make_id, FK countryID
3)model: PK model_id FK dealer_id
4) car properties: PK car_id, FK model_id, FK car_id
5) dealer: dealer_id

How do I get the code to add the appropriate car to the appropriate dealer node without changing the schema structure?
0
Comment
Question by:MichelleLacy
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4 Comments
 
LVL 7

Expert Comment

by:dctuck
ID: 22786926
If you are using an integer as the primary key for tables, each table's first record will have an Identity of 1, so your TreeNode will also have a key of 1 for the first item in each section (hope that makes sense!)
The way I would do it, is to append the ID of the item with the type of item it is, for example, for a make, you could use:
node.Nodes.Add("make_" + dr["make_id"].ToString(), dr["make_name"].ToString());
and for a dealer:
node.Nodes.Add("dealer_" + dr["dealer_id"].ToString(), dr["year"].ToString());
This means the TreeView can differentiate between the different types, so when you search, you have to make sure you use something like:
if (!node.Nodes.ContainsKey("dealer_" + dr["dealer_id"].ToString()))
{
     node.Nodes.Add("dealer_" + dr["dealer_id"].ToString(), dr["year"].ToString());
}
And so on. Hope that helps
Daniel
0
 

Author Comment

by:MichelleLacy
ID: 22787469
sorry there is a couple of typos in the code "year" should be "location".  and the table schema is
1) country: PK countryID
2) make: PK make_id, FK countryID
3) model: PK model_id FK dealer_id
4) car properties: PK car_id, FK model_id, FK make_id
5) dealer: dealer_id
However, my primary key are not integers, they are alpha-numeric, so the code can differientiate between for example a model id and the dealer id.
Is there a way that I can add a condition that tells it to not only look for the dealer id for the mdoel, but also one node up from that, the make_id.   So that it has pass both conditions (be the right make as well be present at a specific dealership?
0
 

Author Comment

by:MichelleLacy
ID: 22792939
I tried a couple of different approaches to solving this problem.  I tried nesting the foreach loops for the last two queries, then I tried with the last three queries so that in order to add a model node, the method would first have to find the make as well as the dealer.  Neither approach worked.  
After looking at my schema model, there is not a direct relationship between my make table and my dealer table.  So there does not appear to be a straightforward way to build a tree with 1st node being country, then make, then dealer, then model.  So I changed the layout of my tree view and got rid of the dealer node altogether.  I added dealer in a separate control drop down box that the users could filter on to narrow down what is shown in the tree.
0
 

Accepted Solution

by:
MichelleLacy earned 0 total points
ID: 22792941

I tried a couple of different approaches to solving this problem.  I tried nesting the foreach loops for the last two queries, then I tried with the last three queries so that in order to add a model node, the method would first have to find the make as well as the dealer.  Neither approach worked.  
After looking at my schema model, there is not a direct relationship between my make table and my dealer table.  So there does not appear to be a straightforward way to build a tree with 1st node being country, then make, then dealer, then model.  So I changed the layout of my tree view and got rid of the dealer node altogether.  I added dealer in a separate control drop down box that the users could filter on to narrow down what is shown in the tree.
0

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