Databases
StackOverflow2013
Postsdbo
POTCollectionItem not initializing default property values
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POTCollectionItem not initializing default property values
    primarykey
    data
    text
    <p>I've been fighting this crazy problem for hours and have gotten nowhere. I have this problem in two completely different projects using a TCollection. When a new collection item is added, I need to initialize the values of that item. However, they're not defaulting at all. I'm even setting them in two completely different places, in the item's constructor, and in the collection's add function - neither of them are working. I can set the values once the items are there, but I need to set default values. I've done collections in the past and never had this problem, I must be missing something here...</p> <pre><code>unit JDGrids; interface uses Classes, Windows, SysUtils, Grids, StrUtils; type TJDGridCol = class; TJDGridCols = class; TJDGridCols = class(TCollection) private fOnEvent: TNotifyEvent; private fOwner: TComponent; procedure DoEvent; property OnEvent: TNotifyEvent read fOnEvent write fOnEvent; protected function GetItem(Index: Integer): TJDGridCol; procedure SetItem(Index: Integer; Value: TJDGridCol); function GetOwner: TPersistent; override; public constructor Create(AOwner: TComponent); destructor Destroy; override; function Add: TJDGridCol; procedure Assign(Source: TPersistent); override; procedure Clear; procedure Delete(Index: Integer); property Items[Index: Integer]: TJDGridCol read GetItem write SetItem; default; end; TJDGridCol = class(TCollectionItem) private fOwner: TComponent; fWidth: Integer; fTitle: String; fCols: TJDGridCols; fOnEvent: TNotifyEvent; fVisible: Bool; procedure SetTitle(const Value: String); procedure SetWidth(const Value: Integer); procedure DoEvent; property OnEvent: TNotifyEvent read fOnEvent write fOnEvent; procedure SetVisible(const Value: Bool); protected function GetDisplayName: String; override; public constructor Create(AOwner: TJDGridCols); destructor Destroy; override; published property Title: String read fTitle write SetTitle; property Width: Integer read fWidth write SetWidth; property Visible: Bool read fVisible write SetVisible; end; implementation { TJDGridCols } constructor TJDGridCols.Create(AOwner: TComponent); begin inherited Create(TJDGridCol); fOwner:= AOwner; end; destructor TJDGridCols.Destroy; begin inherited Destroy; end; function TJDGridCols.Add: TJDGridCol; begin Result:= TJDGridCol(inherited Add); Result.fCols:= Self; Result.fTitle:= 'Column '+IntToStr(Result.ID); Result.fWidth:= 30; Result.fVisible:= True; DoEvent; end; procedure TJDGridCols.Assign(Source: TPersistent); begin inherited Assign(Source); DoEvent; end; procedure TJDGridCols.Clear; begin inherited Clear; DoEvent; end; procedure TJDGridCols.Delete(Index: Integer); begin inherited Delete(Index); DoEvent; end; function TJDGridCols.GetItem(Index: Integer): TJDGridCol; begin Result:= TJDGridCol(inherited Items[Index]); end; function TJDGridCols.GetOwner: TPersistent; begin Result:= fOwner; end; procedure TJDGridCols.SetItem(Index: Integer; Value: TJDGridCol); begin inherited Items[Index]:= Value; DoEvent; end; procedure TJDGridCols.DoEvent; begin if assigned(fOnEvent) then fOnEvent(Self); end; { TJDGridCol } constructor TJDGridCol.Create(AOwner: TJDGridCols); begin inherited Create(AOwner); fOwner:= AOwner.fOwner; fCols:= AOwner; fTitle:= 'Column '+IntToStr(ID); fWidth:= 30; fVisible:= True; end; destructor TJDGridCol.Destroy; begin inherited Destroy; end; procedure TJDGridCol.DoEvent; begin if assigned(fOnEvent) then fOnEvent(Self); end; function TJDGridCol.GetDisplayName: String; begin Result:= fTitle; end; procedure TJDGridCol.SetTitle(const Value: String); begin fTitle:= Value; DoEvent; end; procedure TJDGridCol.SetVisible(const Value: Bool); begin fVisible := Value; DoEvent; end; procedure TJDGridCol.SetWidth(const Value: Integer); begin fWidth := Value; DoEvent; end; end. </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USmenjaraz
    1. USJerry Dodge
    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
    1. This table or related slice is empty.
    1. This table or related slice is empty.
 

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