[SOLVED] Populate Treeview from Table

[Hansvb]

Hi,

In a table you have the following data: GUID, NAME, PARENT.
The table is populated when a TTreeView is saved. The Rootnode then has a GUID but no Parent and the other nodes all have a
GUID and a PARENT. The PARENT guid of a child treenode is de GUID of its parent node. So its al realated.

Now I want to rebuild the Treeview with the in the table.

I think the first thing to do is read all de records of the tabel and put in een array so that I can easily loop through it
:

Code: Pascal  [Select][+][-]

1.   ApiObjectData = record
2.     Guid : String;
3.     ParentFolder : String;
4.     Name : String;
5.   end;
6.   AllApiObjectData = array of ApiObjectData;

Fill the array:

Code: Pascal  [Select][+][-]

1. procedure TFolder.ReadFolderList(var fd: AllApiObjectData);
2. var
3.   SqlText : String;
4.   i : Integer;
5. begin
6.   SqlText := 'Select GUID, NAME, PARENT ' +
7.              'from ' + TableName.FOLDER_LIST;
8.  
9.   With DataModule1 do begin
10.     try
11.       ...
12.       SQLQuery.SQL.Text := SqlText;
13.       SQLQuery.Open;
14.       SQLQuery.First;
15.  
16.       i := 0;
17.       SetLength(fd, SQLQuery.RecordCount);
18.  
19.       while not SQLQuery.Eof do  begin
20.         fd[i].Guid := SQLQuery.FieldByName('GUID').AsAnsiString;
21.         fd[i].ParentFolder := SQLQuery.FieldByName('PARENT').AsAnsiString;
22.         fd[i].Name := SQLQuery.FieldByName('NAME').AsAnsiString;
23.         i += 1;
24.         SQLQuery. next;
25.       end;
26.  
27.       SQLQuery.Close;
28.       SQLite3Connection.Close();
29.  
30.     except
31.       on E : Exception do begin
32.       ...
33.       end;
34.     end;
35.   end;
36. end;

Now the array is filled with all de records, I need to loop throug it and continue looping until all nodes have been read in and the nodes must be assigned to the correct parent. This is where I get stuck

Code: Pascal  [Select][+][-]

1. procedure TFolder.PopulateTreeView(Trv: TTreeView);
2. var
3.   aGuid : String;
4.   fd: AllApiObjectData;
5.   i, j : Integer;
6.   s : String;
7.   RootNode : TTreeNode;
8.   ChildNodes : Array of TTreeNode;
9. begin
10.   Trv.Items.Clear;
11.   ReadFolderList(fd);
12.  
13.   for i:= 0 to Length(fd)-1 do begin
14.     if (fd[i].Guid <> '') and  (fd[i].ParentFolder = '') then begin  // rootnode
15.        RootNode := Trv.Items.Add(nil, fd[i].Name);
16.        aGuid := fd[i].Guid;
17.        break;
18.     end;
19.  
20.     Now search in fd[i].ParentFolder = aGuid. There are a few hits.
21.     How to continue  <----------------
22.  
23.   end;
24. end;  

[ASerge]

If there is so little data that they fit entirely into memory, then maybe not using the database, but just the SaveToFile and LoadFromFile methods built into TTreeView?

[Hansvb]

The data will grow and  the actual record is bigger than in my example.

[cdbc]

Hi
I use something like this:

Code: Pascal  [Select][+][-]

1. function bcGetNodeWithParentByTextAtLevel(aTree: TTreeView;
2.                                           aParent: TTreeNode;
3.                                           const aValue: string;
4.                                           aVisible: boolean;
5.                                           aLevel: integer): TTreeNode;
6. var
7.   Node: TTreeNode;
8. begin
9.   Result:= nil;
10.   if aTree.Items.Count = 0 then exit; { nothing to do }
11.   Node:= aTree.Items[0]; { ie.: root-node }
12.   while Node <> nil do begin
13.     if ((UpperCase(Node.Text) = UpperCase(aValue)) and
14.        (Node.Level = aLevel) and (Node.Parent = aParent)) then begin
15.       Result:= Node;
16.       if aVisible then Result.MakeVisible;
17.       break;
18.     end;
19.     Node:= Node.GetNext;
20.   end;
21. end; { bcGetNodeWithParentByTextAtLevel }
22.  

and use it like this:

Code: Pascal  [Select][+][-]

1. WeekNode:= bcGetNodeWithParentByTextAtLevel(trvNav,YearNode,anItem.Date.WeekNumberAsString,false,2);
2.     if WeekNode <> nil then begin
3.       // do stuff
4.     end;
5.  

HTH
Regards Benny

[ASerge]

The data will grow and  the actual record is bigger than in my example.

But you said: "The table is filled when saving TTreeView". That is, the data is completely in memory.

If the entire data is only in the database, and the part that the user wants to see is loaded into memory, then it is better to load data from the database only according to the visible node. And subload when opening a tree subnode.

[Hansvb]

@Aserge, I want to build the treeview with the data of the database table when de program starts. For that i put the data in an array and then i want to build the treeview with the data in the array. Until now i only seem to be able to build the rootnode and the first level child nodes with this:

Code: Pascal  [Select][+][-]

1. procedure TFolder.PopulateTreeView(Pguid, Cguid : String);
2. var
3.   i: Integer;
4.   ParentTn,  ChildTn  : TTreeNode;
5. begin
6.   if (Pguid = '') and (cGuid = '') then begin  // RootNode
7.     Trv.Items.Clear;
8.     for i:= 0 to Length(fd)-1 do begin
9.       if (fd[i].Guid <> '') and  (fd[i].ParentFolder = '') then begin  // rootnode
10.          ParentTn := Trv.Items.Add(nil, fd[i].Name);
11.          pGuid := fd[i].Guid;
12.          break;
13.       end;
14.     end;
15.   end;
16.  
17.   if (ParentTn <> nil) and (Pguid <> '') and (cGuid = '') then begin  // first level
18.     for i:= 0 to Length(fd)-1 do begin
19.       if (fd[i].Guid <> '') and  (fd[i].ParentFolder = pGuid) then begin  // rootnode
20.         ChildTn :=  Trv.Items.AddChild(ParentTn, fd[i].Name);
21.       end;
22.     end;
23.   end;
24. end;

[egsuh]

I think you will need recursion and TDataSet's filter function. Haven't tested following codes, but this kind of logic is necessary.

Code: Pascal  [Select][+][-]

1. procedure AddChildNodes(node: TTreeNode) ;
2. var
3.      gid : string;
4.      tnode: TTreeNode;
5.      aod: ApiObjectData;
6. begin
7.      if node = nil
8.         then gid := ''
9.         else gid := ApiObjectData(node.data).Guid;
10.    
11.      with SQLQuery do begin
12.             Filter := 'PARENT=''' + gid + '''';   // SQLQuery.Filtered should have been true
13.             First;
14.             while not eof do begin
15.                   New(aod);
16.                   aod^.Name := FieldByName('name').AsString;
17.                   aod^.Guid := FieldByName('Guid').AsString;
18.                   aod^.ParentFolder := FieldByName('Parent').AsString;
19.  
20.                   TreeView.AddChildObject(node, aod^.Name, aod);
21.                   Next;
22.             end;
23.      end;
24.  
25.      tnode := node.GetFirstChild;
26.      while tnode <> nil do begin
27.              AddchildNodes(tnode);
28.              tnode := tnode.GetNextSibling;
29.       end;
30. end;
31.  
32.  
33. //---------------- and calling the procedure somewhere...
34.  
35.  
36. SQLQuery.Filtered := True;
37. AddChildNodes(nil);
38.  
39.  

   
     

[Hansvb]

Hi, it finally works. The treeview is built and if you click on a Node, the data is displayed.


See below. This works, but if there is a better way, please let me know.

Code: Pascal  [Select][+][-]

1. type
2.   PtrApiObject = ^ApiObjectData;
3.   ApiObjectData = record
4.     Id                      : Integer;
5.     Guid                    : String;
6.     ParentFolder            : String;
7.     Name                    : String;
8.   end
9.   AllApiObjectData = array of  ApiObjectData;
10.  
11.  
12. var    
13.   ParentNodes : Array of TTreeNode;
14.   ChildNodes : Array of ApiObjectData;
15.   fd: AllApiObjectData;
16.   Trv : TTreeView;
17.    
18.  
19. procedure TFolder.PopulateTreeView();
20. var
21.   i, p, Counter : Integer;
22.   ParentTn : TTreeNode;
23.   aod : PtrApiObject;
24. begin
25.   if (ParentNodes <> nil) and ( ChildNodes <> nil) then begin   // search for  ChildNodes in fd[i].ParentFolder
26.     for p := 0 to Length(ParentNodes) do begin
27.       for i:= 0 to Length(fd)-1 do begin
28.         if ChildNodes[p].Guid = fd[i].ParentFolder then begin
29.           Counter := Length(ParentNodes);
30.  
31.           New(aod);
32.           aod^.Guid := fd[i].Guid;
33.           aod^.ParentFolder := fd[i].ParentFolder;
34.           aod^.ObjectType := 'Folder';
35.           aod^.Name := fd[i].Name;
36.  
37.           ParentTn := Trv.Items.AddChildObject(ParentNodes[p], fd[i].Name, aod);
38.  
39.           SetLength(ParentNodes, Counter+1);
40.           ParentNodes[Counter] := ParentTn;
41.  
42.           SetLength(ChildNodes, Counter+1);
43.           ChildNodes[Counter].Guid := fd[i].Guid;
44.         end;
45.       end;
46.  
47.       delete(ChildNodes, p, 1);   //Syntax is Delete(fromArray, Index, NumberOfItems); Index is zero based.
48.       delete(ParentNodes, p, 1);
49.  
50.       if (ParentNodes <> nil) and (ChildNodes <> nil) then begin
51.         PopulateTreeView();
52.       end;
53.  
54.       if (ParentNodes = nil) and (ChildNodes = nil) then begin
55.         Exit;
56.       end;
57.  
58.     end;
59.   end
60.   else begin
61.     Counter := Length(ParentNodes);
62.     for i:= 0 to Length(fd)-1 do begin
63.       if (fd[i].Guid <> '') and  (fd[i].ParentFolder = '') then begin  // rootnode
64.  
65.         New(aod);
66.         aod^.Guid := fd[i].Guid;
67.         aod^.ParentFolder := fd[i].ParentFolder;
68.         aod^.ObjectType := 'Folder';
69.         aod^.Name := fd[i].Name;
70.  
71.         ParentTn := Trv.Items.AddObject(nil, fd[i].Name, aod);
72.  
73.         SetLength(ParentNodes, Counter + 1);
74.         ParentNodes[Counter] := ParentTn;
75.  
76.         SetLength(ChildNodes, Counter + 1);
77.         ChildNodes[Counter].Guid := fd[Counter].Guid;
78.         break;
79.       end;
80.     end;
81.     if (ParentTn <> nil)  then begin
82.       PopulateTreeView();
83.     end;
84.   end;
85. end;

[egsuh]

I have confirmed following codes work fine.

If you have to use array definitely, try TFPGMap, etc. so that you can select only child records of a parent node. But this is done by just filtering of TDataset. It makes algorithm very simple.

Code: Pascal  [Select][+][-]

1. type
2.    ApiObjectData = record
3.       name,
4.       guid,
5.       parentfolder : string;
6.    end;
7.    PAOD = ^ApiObjectData;
8.  
9. implementation
10.  
11. procedure Tform1.PopulateTV(node: TTreeNode) ;
12. var
13.      gid : string;
14.      aod: PAOD;
15.      tnode: TTreeNode;
16. begin
17.      if node = nil
18.         then gid := ''
19.         else begin
20.            aod := node.data;
21.            gid := aod^.Guid;
22.         end;
23.  
24.      with BufDataSet1 do begin
25.             Filter := Format('PARENT=''%s''', [gid]);
26.             First;
27.  
28.             while not eof do begin
29.                   New(aod);
30.                   aod^.Name := FieldByName('name').AsString;
31.                   aod^.Guid := FieldByName('Guid').AsString;
32.                   aod^.ParentFolder := FieldByName('Parent').AsString;
33.  
34.                   TreeView1.Items.AddChildObject(node, aod^.Name, aod);
35.                   Next;
36.             end;
37.      end;
38.      if node = nil
39.         then tnode := Treeview1.Items.GetFirstNode
40.         else tnode := node.GetFirstChild;
41.      while tnode <> nil do begin
42.              PopulateTV(tnode);
43.              tnode := tnode.GetNextSibling;
44.       end;
45. end;
46.  
47.  
48. procedure TForm1.Button2Click(Sender: TObject);
49. begin
50.    PopulateTV(nil);
51.    BufDataSet1.Filter := '';
52. end;

[Hansvb]

I will try that.