Databases
StackOverflow2013
Postsdbo
POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
    primarykey
    data
    text
    <p>I am using Delphi2010 and trying to wrap my head around using VirtualStringTree.</p> <p>I've been trying to get it to work with objects and was having no luck until I followed Philipp Frenzel's Virtual TreeView tutorial which I found on the soft-gems.net web site. What I've come up with so far works but I don't think I'm handling the subnodes (i.e. childnodes) correctly.</p> <p>The only thing I've been able to get working is to link the whole object in again for each child and then just display the field I need - but it just feels so wrong.</p> <p>Suggestions/feedback much appreciated.</p> <hr> <p>I have list of objects that I'm trying to hookup with VirtualStringTree where I'm trying to achieve something like this where one of the fields will act as the label to the parent and the rest of the fields show up as childnodes. </p> <ul> <li>Robert Lane <ul> <li>Male </li> <li>35</li> <li>Los Angeles</li> <li>Brunette</li> </ul></li> <li>Jane Doe <ul> <li>Female</li> <li>19</li> <li>Denver</li> <li>Redhead</li> </ul></li> </ul> <p>This how my class is set up. </p> <pre><code>type PTreeData = ^TTreeData; TTreeData = record FObject : TObject; end; TCustomerNode = class(TObject) private fName: string; fSex: string; fAge: integer; fHair: string; //... public property Name: string read fName write fName; //... end; </code></pre> <p>Once I populate the objects I add them to another class (CustomerObjectList) based off of TList which is mentioned below. </p> <p>Here is where I connect VirtualStringTree with my object list</p> <pre><code>procedure TfrmMain.btnLoadDataClick(Sender: TObject); var i, j : integer; CustomerDataObject: TCustomerNode; RootXNode, XNode: PVirtualNode; Data: PTreeData; begin vstree.NodeDataSize := SizeOf( TTreeData ); vstree.BeginUpdate; for i := 0 to CustomerObjectList.Count - 1 do begin CustomerDataObject := CustomerObjectList[i]; //load data for parent node RootXNode := vstree.AddChild(nil); Data := vstree.GetNodeData(RootXNode); Data^.FObject:= PINodeSource; //now add children for rest of fields //Isn't there a better way to do this? for j := 1 to NUMBERofFIELDS -1 do //first field is label for parent so -1 begin XNode := vstree.AddChild(RootXNode); Data := vstree.GetNodeData(XNode); Data^.FObject:= PINodeSource; end; end; vstree.EndUpdate; end; procedure TfrmMain.vstreeGetText(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex; TextType: TVSTTextType; var CellText: string); var Data : PTreeData; begin Data := vstObjects.GetNodeData(Node); ////if Node.ChildCount = 0 then //edit - oops typo! if Node.ChildCount &gt; 0 then begin CellText := TCustomerNode(Data.FObject).Name; exit; end; //handle childnodes case Node.Index of 0: CellText := TCustomerNode(Data.FObject).Sex; 1: CellText := IntToStr(TCustomerNode(Data.FObject).Age); 2: CellText := TCustomerNode(Data.FObject).Hair; 3: CellText := TCustomerNode(Data.FObject).City; end; end; </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USIan Boyd
    1. USTheSteven
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. USnorgepaul
      1. VTFavorite
    1. COIf you already have an objectlist that holds all your objects then why not only needs hold the index in the objectlist in the TreeData record? Or in the case of multiple lists the list and the index.
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. USRemko
    2. COSorry maybe I just need more coffee but I'm not getting what your saying. Hold the index in the objectlist in the TreeData record? Could you please provide more information? Thanks
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. USTheSteven
    3. COHere's the link to Philipp Frenzel's "Treeview_Tutorial.pdf" that I mentioned http://www.soft-gems.net/supplement/download.php?ID=79
      singulars
      1. POVirtualStringTree - Correct way to add/handle subnodes/childnodes when using objects?
      1. USTheSteven
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload