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All Atlas Virtual Grid components · Atlas Virtual Grid guide

EAtlasGridError

The exception class of Atlas Virtual Grid, and the way a data source refuses a value.

Class Unit Atlas.VGridData · Inherits Exception · Product Atlas Virtual Grid

Description

Raised for cells and columns that do not exist, values that do not fit a column, writes to read-only sources and columns, unsupported file types and image sizes, and refused chart values. Raise it yourself from OnSetCell or a custom SetCell to refuse a value. The grid catches this class, and only this class, around edits: it reports the message through OnEditError and LastError and keeps the old value. Atlas Plot errors raised while exporting a picture or writing to a chart are translated into it.

This type has no members of its own beyond those listed in its description.

Examples

Refuse a value

The price source refuses zero and negative prices.

pascal
uses System.Classes, Atlas.VGridData;

type
  TPrices = class(TComponent)
  private
    FPrices: TArray<Double>;
    FData: TAtlasVirtualData;
    procedure GetPrice(Sender: TObject; Column, Row: Integer; var Cell: TAtlasCell);
    procedure SetPrice(Sender: TObject; Column, Row: Integer; const Cell: TAtlasCell);
  public
    constructor Create(AOwner: TComponent); override;
    property Data: TAtlasVirtualData read FData;
  end;

constructor TPrices.Create(AOwner: TComponent);
begin
  inherited;
  FPrices := [9.5, 12, 30];
  FData := TAtlasVirtualData.Create(Self);
  FData.AddColumn('Price', ckNumber);
  FData.OnGetCell := GetPrice;
  FData.OnSetCell := SetPrice;               // without a handler every column is read-only
  FData.RowCount := Length(FPrices);
end;

procedure TPrices.GetPrice(Sender: TObject; Column, Row: Integer; var Cell: TAtlasCell);
begin
  Cell := TAtlasCell.OfNumber(FPrices[Row]);
end;

procedure TPrices.SetPrice(Sender: TObject; Column, Row: Integer; const Cell: TAtlasCell);
begin
  // The text has already been parsed as a number. Raising EAtlasGridError
  // refuses the value; a grid keeps its editor open and reports the message.
  if Cell.IsNull or (Cell.Number <= 0) then
    raise EAtlasGridError.Create('A price must be above zero');
  FPrices[Row] := Cell.Number;
end;

TAtlasVirtualGrid · TAtlasVirtualData · TAtlasGridData

Also in Atlas Virtual Grid

TAtlasVirtualGrid · TAtlasMemoryData · TAtlasVirtualData · TAtlasPlotData