How to Display and Edit MEMO Fields in Delphis TDBGrid

How to Display and Edit MEMO Fields in Delphis TDBGrid   If you are developing database applications with tables containing MEMO fields, youll notice that, by default, the TDBGrid component does not show the contents of a MEMO field inside a DBGrid cell. This article provides an idea of how to solve this TMemoFields issue (with a few more tricks)... TMemoField Memo fields are used to represent lengthy text or combinations of text and numbers. When building database applications using Delphi, the TMemoField object is used to represent a memo field in a dataset. TMemoField encapsulates the fundamental behavior common to fields that contain text data or arbitrary length. In most databases, the size of the Memo field is limited by the size of the database. While you can display the contents of a MEMO field in a TDBMemo component, by design the TDBGrid will only display (Memo) for the contents of such fields. In order to actually display some text (from the MEMO field) in the appropriate DBGrid cell, youll only need to add a simple line of code ... For the purpose of the next discussion, lets say you have a database table named TestTable with at least one MEMO field named Data. OnGetText To show the contents of a MEMO field in the DBGrid, you need to attach a simple line of code in the fields  OnGetText  event. The easiest way to create the OnGetText event handler is to use the Fields editor at design time to create a persistent field component for the memo field: Connect your TDataset descendant component (TTable, TQuery, TADOTable, TADOQuery ....) to the TestTable database table.Double click the dataset component to open the Fields editorAdd the MEMO field to the list of persistent fieldsSelect the MEMO field in the Fields editorActivate the Events tab in the Object InspectorDouble click the OnGetText event to create the event handler Add the next line of code (italicized below): procedure TForm1.DBTableDataGetText( Sender: TField; var Text: String; DisplayText: Boolean); begin Text : Copy(DBTableData.AsString, 1, 50); Note: the dataset object is called DBTable, the MEMO field is called DATA, and therefore, by default, the TMemoField connected to the MEMO database field is called DBTableData. By assigning  DBTableData.AsString  to the  Text  parameter of the OnGetText event, we tell Delphi to display ALL the text from the MEMO field in a DBGrid cell.You can also  adapt the DisplayWidth  of the memo field to a more appropriate value. Note: since MEMO fields can be quite BIG, it is a good idea to show only a part of it. In the above code, only the first 50 characters are displayed. Editing on a separate form By default, the TDBGrid does not allow editing of MEMO fields. If you want to enable in place editing, you could add some code to react on a user action that shows a separate window that allows editing using a TMemo component.For the sake of simplicity well open an editing window when ENTER is pressed on a MEMO field in a DBGrid.Lets use the  KeyDown  event of a DBGrid component: procedure TForm1.DBGrid1KeyDown( Sender: TObject; var Key: Word; Shift: TShiftState); begin if Key VK_RETURN then begin if DBGrid1.SelectedField DBTableData then with TMemoEditorForm.Create(nil) do try DBMemoEditor.Text : DBTableData.AsString; ShowModal; DBTable.Edit; DBTableData.AsString : DBMemoEditor.Text; finally Free; end; end; end; Note 1: the TMemoEditorForm is a secondary form containing only one component: DBMemoEditor (TMemo).Note 2: the TMemoEditorForm was removed from the Auto-create forms list in the Project Options dialog window. Lets see what happens in the DBGrid1s KeyDown event handler: When a user presses the ENTER key (we are comparing the Key parameter to the VK_RETURN  virtual key code) [Key VK_RETURN],If the currently selected field in the DBGrid is our MEMO field (DBGrid1.SelectedField DBTableData),We create the TMemoEditorForm [TMemoEditorForm.Create(nil)],Send the value of the MEMO field to the TMemo component [DBMemoEditor.Text : DBTableData.AsString],Display the form modally [ShowModal],When a user finishes with editing and closes the form, we need to put the dataste into the Edit mode [DBTable.Edit],In order to be able to assign the edited value back to our MEMO field [DBTableData.AsString : DBMemoEditor.Text]. Note: if you are looking for more TDBGrid related articles and usage tips, be sure to visit: TDBGrid to the MAX tips collection.