How to refresh Livebinding for TListView and TFDMemTable? - delphi

Question

I have a TListView livebinded with TFDMemTable. I also have a TButton that adds the item on the TFDMemTable which obviously shown in the TListView after adding the item. The TListView is located in one of the TTabItem of TTabControl.
My problem is, when I changed the tab at runtime and go back to TListView tab to add more item, the previously shown data will become empty after adding more item.
I can confirm that the data in the TFDMemTable are still intact including the newly added ones.
I suspect the livebinding needs to be refreshed in order to get all the data back to TListView.
Does anyone have any idea on how to refresh the livebinding at runtime?
P.S. I hope the above explains my issue clearly. Otherwise, please let me know if you need more details.
UPDATE 1: MINIMUM REPRODUCIBLE EXAMPLE
Here's the least that I can do for the MRE, not the exact scenario of my case but should be the same issue. You will come to notice after adding list on the TabItem2 and you go back to TabItem1 to add more item on the lists, the existing detail on the list will be gone.
FMX Procedure
unit TabbedFormwithNavigation;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.TabControl, FMX.StdCtrls, FMX.Controls.Presentation,
FMX.Gestures, System.Actions, FMX.ActnList, FMX.ListView.Types,
FMX.ListView.Appearances, FMX.ListView.Adapters.Base, REST.Types,
FireDAC.Stan.Intf, FireDAC.Stan.Option, FireDAC.Stan.Param,
FireDAC.Stan.Error, FireDAC.DatS, FireDAC.Phys.Intf, FireDAC.DApt.Intf,
System.Rtti, System.Bindings.Outputs, Fmx.Bind.Editors, Data.Bind.EngExt,
Fmx.Bind.DBEngExt, Data.Bind.Components, Data.Bind.DBScope, Data.DB,
FireDAC.Comp.DataSet, FireDAC.Comp.Client, REST.Response.Adapter, REST.Client,
Data.Bind.ObjectScope, FMX.ListView;
type
TTabbedwithNavigationForm = class(TForm)
TabControl1: TTabControl;
TabItem1: TTabItem;
TabItem2: TTabItem;
GestureManager1: TGestureManager;
ActionList1: TActionList;
NextTabAction1: TNextTabAction;
PreviousTabAction1: TPreviousTabAction;
lsv1: TListView;
rsc1: TRESTClient;
rsq1: TRESTRequest;
rsp1: TRESTResponse;
rsd1: TRESTResponseDataSetAdapter;
mtb1: TFDMemTable;
bdr1: TBindSourceDB;
bdl1: TBindingsList;
lsv2: TListView;
rsc2: TRESTClient;
rsq2: TRESTRequest;
rsp2: TRESTResponse;
rsd2: TRESTResponseDataSetAdapter;
mtb2: TFDMemTable;
bdr2: TBindSourceDB;
lcf1: TLinkListControlToField;
btn1: TButton;
lsv3: TListView;
mtb3: TFDMemTable;
strngfldmtb3brandname: TStringField;
strngfldmtb3brand: TStringField;
bdr3: TBindSourceDB;
lcf3: TLinkListControlToField;
lcf2: TLinkListControlToField;
pnl1: TPanel;
lbl1: TLabel;
pnl2: TPanel;
lbl2: TLabel;
pnl3: TPanel;
lbl3: TLabel;
procedure GestureDone(Sender: TObject; const EventInfo: TGestureEventInfo; var Handled: Boolean);
procedure FormCreate(Sender: TObject);
procedure FormKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
procedure lsv1ItemClick(const Sender: TObject; const AItem: TListViewItem);
procedure btn1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
TabbedwithNavigationForm: TTabbedwithNavigationForm;
implementation
{$R *.fmx}
procedure TTabbedwithNavigationForm.btn1Click(Sender: TObject);
var
brandname : string;
begin
brandname := mtb2.Lookup('name', lsv2.Items[lsv2.ItemIndex].Text, 'name');
// ShowMessage(lsv2.Items[lsv2.ItemIndex].Text);
if mtb3.Locate('brandname', brandname, []) = False then
begin
mtb3.DisableControls;
mtb3.Append;
mtb3.FieldByName('brandname').AsString := brandname;
mtb3.EnableControls;
mtb3.Post;
end;
end;
procedure TTabbedwithNavigationForm.FormCreate(Sender: TObject);
begin
{ This defines the default active tab at runtime }
TabControl1.ActiveTab := TabItem1;
rsq1.Execute;
end;
procedure TTabbedwithNavigationForm.FormKeyUp(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
begin
if Key = vkHardwareBack then
begin
if (TabControl1.ActiveTab = TabItem1) then
begin
Key := 0;
end;
end;
end;
procedure TTabbedwithNavigationForm.GestureDone(Sender: TObject; const EventInfo: TGestureEventInfo; var Handled: Boolean);
begin
case EventInfo.GestureID of
sgiLeft:
begin
if TabControl1.ActiveTab <> TabControl1.Tabs[TabControl1.TabCount - 1] then
TabControl1.ActiveTab := TabControl1.Tabs[TabControl1.TabIndex + 1];
Handled := True;
end;
sgiRight:
begin
if TabControl1.ActiveTab <> TabControl1.Tabs[0] then
TabControl1.ActiveTab := TabControl1.Tabs[TabControl1.TabIndex - 1];
Handled := True;
end;
end;
end;
procedure TTabbedwithNavigationForm.lsv1ItemClick(const Sender: TObject;
const AItem: TListViewItem);
var
SearchItem : String;
begin
//place the equivalent api for the meta click
SearchItem := lsv1.Items[lsv1.ItemIndex].Text;
rsc2.BaseURL := 'https://nm5c906csg.execute-api.ap-southeast-1.amazonaws.com/v0/dbqueries?search-item=' + SearchItem;
//execute api request for the searches
rsq2.Execute;
TabControl1.TabIndex := 1;
end;
end.
FMX File
object TabbedwithNavigationForm: TTabbedwithNavigationForm
Left = 0
Top = 0
Caption = 'Form56'
ClientHeight = 596
ClientWidth = 405
FormFactor.Width = 320
FormFactor.Height = 480
FormFactor.Devices = [Desktop]
OnCreate = FormCreate
OnKeyUp = FormKeyUp
DesignerMasterStyle = 0
object TabControl1: TTabControl
Touch.GestureManager = GestureManager1
OnGesture = GestureDone
Align = Client
FullSize = True
Size.Width = 405.000000000000000000
Size.Height = 596.000000000000000000
Size.PlatformDefault = False
TabHeight = 49.000000000000000000
TabIndex = 1
TabOrder = 0
TabPosition = PlatformDefault
Sizes = (
405s
547s
405s
547s)
object TabItem1: TTabItem
CustomIcon = <
item
end>
IsSelected = False
Size.Width = 201.000000000000000000
Size.Height = 49.000000000000000000
Size.PlatformDefault = False
StyleLookup = 'tabitemfavorites'
TabOrder = 0
Text = 'TabItem1'
ExplicitSize.cx = 101.000000000000000000
ExplicitSize.cy = 49.000000000000000000
object lsv1: TListView
ItemAppearanceClassName = 'TListItemAppearance'
ItemEditAppearanceClassName = 'TListItemShowCheckAppearance'
HeaderAppearanceClassName = 'TListHeaderObjects'
FooterAppearanceClassName = 'TListHeaderObjects'
ItemIndex = 0
Align = Client
Size.Width = 405.000000000000000000
Size.Height = 487.000000000000000000
Size.PlatformDefault = False
TabOrder = 0
OnItemClick = lsv1ItemClick
end
object pnl1: TPanel
Align = Top
Size.Width = 405.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TabOrder = 1
object lbl1: TLabel
Align = Client
StyledSettings = [Family, FontColor]
Margins.Left = 60.000000000000000000
Margins.Right = 60.000000000000000000
Size.Width = 285.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TextSettings.Font.Size = 14.000000000000000000
TextSettings.Font.StyleExt = {00070000000000000004000000}
TextSettings.HorzAlign = Center
Text = 'Please select an item here to filter out items for TabItem2.'
TabOrder = 0
end
end
end
object TabItem2: TTabItem
CustomIcon = <
item
end>
IsSelected = True
Size.Width = 202.000000000000000000
Size.Height = 49.000000000000000000
Size.PlatformDefault = False
StyleLookup = 'tabitemcontacts'
TabOrder = 0
Text = 'TabItem2'
ExplicitSize.cx = 102.000000000000000000
ExplicitSize.cy = 49.000000000000000000
object lsv2: TListView
ItemAppearanceClassName = 'TImageListItemBottomDetailAppearance'
ItemEditAppearanceClassName = 'TImageListItemBottomDetailShowCheckAppearance'
HeaderAppearanceClassName = 'TListHeaderObjects'
FooterAppearanceClassName = 'TListHeaderObjects'
ItemIndex = 0
Align = Top
Position.Y = 60.000000000000000000
Size.Width = 405.000000000000000000
Size.Height = 221.000000000000000000
Size.PlatformDefault = False
TabOrder = 0
end
object btn1: TButton
Align = Top
StyledSettings = [Family, FontColor]
Position.Y = 281.000000000000000000
Size.Width = 405.000000000000000000
Size.Height = 40.000000000000000000
Size.PlatformDefault = False
TabOrder = 1
Text = 'SELECT'
TextSettings.Font.Size = 14.000000000000000000
TextSettings.Font.StyleExt = {00070000000000000004000000}
OnClick = btn1Click
end
object lsv3: TListView
ItemAppearanceClassName = 'TImageListItemBottomDetailAppearance'
ItemEditAppearanceClassName = 'TImageListItemBottomDetailShowCheckAppearance'
HeaderAppearanceClassName = 'TListHeaderObjects'
FooterAppearanceClassName = 'TListHeaderObjects'
Align = Client
Size.Width = 405.000000000000000000
Size.Height = 166.000000000000000000
Size.PlatformDefault = False
TabOrder = 2
end
object pnl2: TPanel
Align = Top
Size.Width = 405.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TabOrder = 3
object lbl2: TLabel
Align = Client
StyledSettings = [Family, FontColor]
Margins.Left = 30.000000000000000000
Margins.Right = 30.000000000000000000
Size.Width = 345.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TextSettings.Font.Size = 14.000000000000000000
TextSettings.Font.StyleExt = {00070000000000000004000000}
TextSettings.HorzAlign = Center
Text =
'Select an item below then click the "SELECT" button to list down' +
' the items selected.'
TabOrder = 0
end
end
object pnl3: TPanel
Align = Bottom
Position.Y = 487.000000000000000000
Size.Width = 405.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TabOrder = 4
object lbl3: TLabel
Align = Client
StyledSettings = [Family]
Size.Width = 405.000000000000000000
Size.Height = 60.000000000000000000
Size.PlatformDefault = False
TextSettings.Font.StyleExt = {00070000000000000004000000}
TextSettings.FontColor = claRed
TextSettings.HorzAlign = Center
Text =
'The error comes when you go back to TabItem1 and select another ' +
'item, the existing details on the list will be gone.'
TabOrder = 0
end
end
end
end
object GestureManager1: TGestureManager
Sensitivity = 80.000000000000000000
Left = 48
Top = 185
GestureData = <
item
Control = TabControl1
Collection = <
item
GestureID = sgiLeft
end
item
GestureID = sgiRight
end>
end>
end
object ActionList1: TActionList
Left = 48
Top = 120
object NextTabAction1: TNextTabAction
Category = 'Tab'
end
object PreviousTabAction1: TPreviousTabAction
Category = 'Tab'
end
end
object rsc1: TRESTClient
Accept = 'application/json, text/plain; q=0.9, text/html;q=0.8,'
AcceptCharset = 'utf-8, *;q=0.8'
BaseURL =
'https://bs3winlz02.execute-api.ap-southeast-1.amazonaws.com/v0/d' +
'bqueries'
Params = <>
Left = 136
Top = 120
end
object rsq1: TRESTRequest
Client = rsc1
Params = <>
Response = rsp1
SynchronizedEvents = False
Left = 136
Top = 184
end
object rsp1: TRESTResponse
ContentType = 'application/json'
Left = 136
Top = 248
end
object rsd1: TRESTResponseDataSetAdapter
Active = True
Dataset = mtb1
FieldDefs = <>
Response = rsp1
Left = 136
Top = 312
end
object mtb1: TFDMemTable
Active = True
FieldDefs = <
item
Name = 'meta'
DataType = ftWideString
Size = 255
end>
IndexDefs = <>
FetchOptions.AssignedValues = [evMode]
FetchOptions.Mode = fmAll
ResourceOptions.AssignedValues = [rvSilentMode]
ResourceOptions.SilentMode = True
UpdateOptions.AssignedValues = [uvCheckRequired, uvAutoCommitUpdates]
UpdateOptions.CheckRequired = False
UpdateOptions.AutoCommitUpdates = True
StoreDefs = True
Left = 136
Top = 376
end
object bdr1: TBindSourceDB
DataSet = mtb1
ScopeMappings = <>
Left = 136
Top = 440
end
object bdl1: TBindingsList
Methods = <>
OutputConverters = <>
Left = 20
Top = 5
object lcf1: TLinkListControlToField
Category = 'Quick Bindings'
DataSource = bdr1
FieldName = 'meta'
Control = lsv1
FillExpressions = <>
FillHeaderExpressions = <>
FillBreakGroups = <>
end
object lcf3: TLinkListControlToField
Category = 'Quick Bindings'
DataSource = bdr3
FieldName = 'brandname'
Control = lsv3
FillExpressions = <
item
SourceMemberName = 'brand'
ControlMemberName = 'Detail'
end>
FillHeaderExpressions = <>
FillBreakGroups = <>
end
object lcf2: TLinkListControlToField
Category = 'Quick Bindings'
DataSource = bdr2
FieldName = 'name'
Control = lsv2
FillExpressions = <
item
SourceMemberName = 'brand'
ControlMemberName = 'Detail'
end>
FillHeaderExpressions = <>
FillBreakGroups = <>
end
end
object rsc2: TRESTClient
Accept = 'application/json, text/plain; q=0.9, text/html;q=0.8,'
AcceptCharset = 'utf-8, *;q=0.8'
BaseURL =
'https://nm5c906csg.execute-api.ap-southeast-1.amazonaws.com/v0/d' +
'bqueries?search-item=sage'
Params = <>
Left = 200
Top = 120
end
object rsq2: TRESTRequest
Client = rsc2
Params = <>
Response = rsp2
SynchronizedEvents = False
Left = 200
Top = 184
end
object rsp2: TRESTResponse
ContentType = 'application/json'
Left = 200
Top = 248
end
object rsd2: TRESTResponseDataSetAdapter
Active = True
Dataset = mtb2
FieldDefs = <>
Response = rsp2
Left = 200
Top = 312
end
object mtb2: TFDMemTable
Active = True
FieldDefs = <
item
Name = 'brand'
DataType = ftWideString
Size = 255
end
item
Name = 'name'
DataType = ftWideString
Size = 255
end
item
Name = 'description'
DataType = ftWideString
Size = 255
end>
IndexDefs = <>
FetchOptions.AssignedValues = [evMode]
FetchOptions.Mode = fmAll
ResourceOptions.AssignedValues = [rvSilentMode]
ResourceOptions.SilentMode = True
UpdateOptions.AssignedValues = [uvCheckRequired, uvAutoCommitUpdates]
UpdateOptions.CheckRequired = False
UpdateOptions.AutoCommitUpdates = True
StoreDefs = True
Left = 200
Top = 376
end
object bdr2: TBindSourceDB
DataSet = mtb2
ScopeMappings = <>
Left = 200
Top = 440
end
object mtb3: TFDMemTable
Active = True
FetchOptions.AssignedValues = [evMode]
FetchOptions.Mode = fmAll
ResourceOptions.AssignedValues = [rvSilentMode]
ResourceOptions.SilentMode = True
UpdateOptions.AssignedValues = [uvCheckRequired, uvAutoCommitUpdates]
UpdateOptions.CheckRequired = False
UpdateOptions.AutoCommitUpdates = True
Left = 264
Top = 376
object strngfldmtb3brandname: TStringField
FieldName = 'brandname'
Size = 200
end
object strngfldmtb3brand: TStringField
FieldKind = fkLookup
FieldName = 'brand'
LookupDataSet = mtb2
LookupKeyFields = 'name'
LookupResultField = 'brand'
KeyFields = 'brandname'
Size = 200
Lookup = True
end
end
object bdr3: TBindSourceDB
DataSet = mtb3
ScopeMappings = <>
Left = 264
Top = 440
end
end

Answer 1

The error lies on the LookUp field I created in the FDMemTable (mtb3). I avoided those. Instead, I create a normal data field and directly took the data from TListView (lsv2) as shown below:
FMX Procedure
procedure TTabbedwithNavigationForm.btn1Click(Sender: TObject);
var
brandname, brand : string;
begin
brandname := mtb2.Lookup('name', lsv2.Items[lsv2.ItemIndex].Text, 'name');
brand := mtb2.Lookup('name', lsv2.Items[lsv2.ItemIndex].Text, 'brand');
if mtb3.Locate('brandname', brandname, []) = False then
begin
mtb3.DisableControls;
mtb3.Append;
mtb3.FieldByName('brandname').AsString := brandname;
mtb3.FieldByName('brand').AsString := brand; //manually coded instead of lookup field in the fdmemtable (mtb3)
mtb3.EnableControls;
mtb3.Post;
end;
end;
FMX File
object mtb3: TFDMemTable
Active = True
FieldDefs = <
item
Name = 'brandname'
DataType = ftString
Size = 200
end
item
Name = 'brand'
DataType = ftString // defined as data instead of lookup
Size = 100
end>
IndexDefs = <>
FetchOptions.AssignedValues = [evMode]
FetchOptions.Mode = fmAll
ResourceOptions.AssignedValues = [rvSilentMode]
ResourceOptions.SilentMode = True
UpdateOptions.AssignedValues = [uvCheckRequired, uvAutoCommitUpdates]
UpdateOptions.CheckRequired = False
UpdateOptions.AutoCommitUpdates = True
StoreDefs = True
Left = 264
Top = 376
object strngfldmtb3brandname: TStringField
FieldName = 'brandname'
Size = 200
end
object strngfldmtb3brand: TStringField
FieldName = 'brand'
Size = 100
end
end