[SOLVED] Reading a registry key

[petevick]

I'm trying to read the values of the registry key at....

Code: Pascal  [Select][+][-]

1. \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders

....so far I've managed to get as far as Installer, but I can't seem to be able to read Folders. In the following scrap of code reg.OpenKeyReadOnly() is true, but reg.KeyExists() is false.....

Code: Pascal  [Select][+][-]

1. var
2.     reg: TRegistry;
3.    ....
4.    ....
5.    ....
6.    reg := TRegistry.Create(KEY_READ);
7.    reg.RootKey := HKEY_LOCAL_MACHINE;
8.    if reg.OpenKeyReadOnly('\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer')
9.    then begin
10.     if reg.KeyExists('Folders') then begin
11.      ....
12.      ....
13.      ....
14.     end;
15.      reg.CloseKey;
16.    end;
17.  

Using Regedit it appears that the Folders key is a list of folder paths that I'll hopefully be able to read in as a TStringArray, this will then enable me to search for the path of a particular application.

This is my first foray into working with the registry and I'm not enjoying it 

[Bart]

Hi,

I made a test.
In RegEdit: Computer\HKEY_CURRENT_USER\SOFTWARE\FPCTEST\Foldertest
There created Folders (type REG_MULTI_SZ)
Folders contains 3 strings.

Using this code:

Code: Pascal  [Select][+][-]

1. var
2.   R: TRegistry;
3.   B: Boolean;
4.   SL: TStringList;
5.   i: Integer;
6.   S: String;
7. begin
8.   R := TRegistry.Create(KEY_READ);
9.   SL := TStringList.Create;
10.   try
11.     R.RootKey := HKEY_CURRENT_USER;
12.     B := R.OpenKeyReadOnly('Software\FPCTEST\Foldertest');
13.     Assert(B,'OpenKey failed.');
14.     B := R.ValueExists('Folders');
15.     writeln('ValueExists(''Folders'')=',B);
16.     R.ReadStringList('Folders',SL);
17.     writeln('Read Folders:');
18.     writeln('SL.Count: ',SL.Count);
19.     for i := 0 to SL.Count-1 do writeln(i:2,': ',SL[i]);
20.   finally
21.     SL.Free;
22.     R.Free;
23.   end;
24. end.

This outputs:

Code: [Select]

C:\Users\Bart\LazarusProjecten\bugs\Console\registry>multi
ValueExists('Folders')=TRUE
Read Folders:
SL.Count: 3
 0: Folder0
 1: Folder1
 2: Folder2
Fpc 3.2.2-win32 on Win10.

Notice that a REG_MULTI_SZ entry is a Value, not a Key, hence KeyExists is the wrong call here, you must use ValueExists.

Bart

[petevick]

Thanks for the reply Bart.
Using your code but my reg key path....

Code: Pascal  [Select][+][-]

1. var
2.   R: TRegistry;
3.   B: Boolean;
4.   SL: TStringList;
5.   i: Integer;
6.   S: String;
7. begin
8.   R := TRegistry.Create(KEY_READ);
9.   SL := TStringList.Create;
10.   try
11.     R.RootKey := HKEY_LOCAL_MACHINE;
12.     B := R.OpenKeyReadOnly(SOFTWARE\Microsoft\Windows\CurrentVersion\Installer');
13.    Assert(B,'OpenKey failed.');
14.    B := R.ValueExists('Folders');
15.    writeln('ValueExists(''Folders'')=',B);
16.    R.ReadStringList('Folders',SL);
17.    writeln('Read Folders:');
18.    writeln('SL.Count: ',SL.Count);
19.    for i := 0 to SL.Count-1 do writeln(i:2,': ',SL[i]);
20.  finally
21.    SL.Free;
22.    R.Free;
23.  end;
24. end.

....at line 12 B is true, but at line 14 B is false, it's like Folders doesn't exist, but it does as can be seen in the attachment.

[ASerge]

but reg.KeyExists() is false.....

This is strange. I have this code that outputs the entire list:

Code: Pascal  [Select][+][-]

1. uses Registry;
2.  
3. procedure TForm1.Button1Click(Sender: TObject);
4. var
5.   R: TRegistry;
6. begin
7.   R := TRegistry.Create;
8.   try
9.     R.RootKey := HKEY_LOCAL_MACHINE;
10.     if R.OpenKeyReadOnly('\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') then
11.       R.GetValueNames(Memo1.Lines);
12.   finally
13.     R.Free;
14.   end;
15. end;

[Bart]

OK your setup is different from mine.
Your "Folders" actually is a key.
And it has several Values in it.

I made a similar setup:

Computer\HKEY_CURRENT_USER\SOFTWARE\FPCTEST\Foldertest2
There I have key Folders
In Folder I have 2 Values: Folder1, Folder2

Now using this code:

Code: Pascal  [Select][+][-]

1. var
2.   R: TRegistry;
3.   B: Boolean;
4.   S: String;
5. begin
6.   R := TRegistry.Create(KEY_READ);
7.   try
8.     R.RootKey := HKEY_CURRENT_USER;
9.     writeln(format('CurrentPath: "%s"',[String(R.CurrentPath)]));
10.     repeat
11.       write('Key: ');
12.       readln(S);
13.       if (S <> '') then
14.       begin
15.         B := R.KeyExists(S);
16.         writeln('KeyExists(''',S,''')=',B);
17.         B := R.OpenKey(S,False);
18.         if B then
19.           writeln(format('CurrentPath: "%s"',[String(R.CurrentPath)]))
20.         else
21.           writeln(format('Unable to open key: "%s"',[S]));
22.       end;
23.     until (S='');
24.   finally
25.     R.Free;
26.   end;
27. end.

I can do this:

Code: [Select]

C:\Users\Bart\LazarusProjecten\bugs\Console\registry>cpath
CurrentPath: ""
Key: software
KeyExists('software')=TRUE
CurrentPath: "software"
Key: fpctest
KeyExists('fpctest')=TRUE
CurrentPath: "software\fpctest"
Key: foldertest2
KeyExists('foldertest2')=TRUE
CurrentPath: "software\fpctest\foldertest2"
Key: folders
KeyExists('folders')=TRUE
CurrentPath: "software\fpctest\foldertest2\folders"
I attached a screenshot of my setup.

Bart

[petevick]

Thanks again Bart and ASerge, I'll check out your posts tomorrow 👍

[petevick]

but reg.KeyExists() is false.....

This is strange. I have this code that outputs the entire list:

Code: Pascal  [Select][+][-]

1. uses Registry;
2.  
3. procedure TForm1.Button1Click(Sender: TObject);
4. var
5.   R: TRegistry;
6. begin
7.   R := TRegistry.Create;
8.   try
9.     R.RootKey := HKEY_LOCAL_MACHINE;
10.     if R.OpenKeyReadOnly('\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') then
11.       R.GetValueNames(Memo1.Lines);
12.   finally
13.     R.Free;
14.   end;
15. end;

Your code doesn't work on that particular key, but it works fine on \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\AllowedDragImageExts and lists all the file extensions, so why the hell isn't it working on \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders 

Is it possible that running Win10 in a VirtualBox has something to do with it, seems unlikely to me 

[petevick]

This is a very small project that has two buttons, the first 'should' list the install folder paths, which I can't get to work, the second lists file extensions, which does work for me. Could someone confirm one way or another which are working please.

[petevick]

I thought it might have been a permissions issue, but the permissions for both keys appear to be the same. 

[ASerge]

Could someone confirm one way or another which are working please.

Both are working. Lazarus 3.2 x64, FPC 3.2.2

[petevick]

Could someone confirm one way or another which are working please.

Both are working. Lazarus 3.2 x64, FPC 3.2.2

Thanks ASerge, it looks like I'm stuffed then  :'(

[Bart]

Running in 32-bit this  key ('SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') does not seem to exist, but it runs OK in 64-bit mode.

Bart

[petevick]

Running in 32-bit this  key ('SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') does not seem to exist, but it runs OK in 64-bit mode.

Bart

Thanks Bart, just one more inconsistency to deal with.
I've just tried it with an old Windows 7 VM and both work on that, so there's a bit of hope 

[Bart]

Running in 32-bit this  key ('SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') does not seem to exist, but it runs OK in 64-bit mode.

Bart

Thanks Bart, just one more inconsistency to deal with.

Well, inconsistency added by MS, not by fpc.

Bart

[petevick]

Running in 32-bit this  key ('SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\Folders') does not seem to exist, but it runs OK in 64-bit mode.

Bart

Thanks Bart, just one more inconsistency to deal with.

Well, inconsistency added by MS, not by fpc.

Bart

yes indeed, that's what I meant