如何解决如何刷新TListView和TFDMemTable的Livebinding？
我有一个与TFDMemTable绑定在一起的TListView。我也有一个TButton，将项目添加到TFDMemTable上，添加项目后，该项目显然显示在TListView中。 TListView位于TTabControl的TTabItem之一。
我的问题是，当我在运行时更改选项卡并返回到TListView选项卡以添加更多项时，先前显示的数据在添加更多项后将变为空。
我可以确认TFDMemTable中的数据仍然完整无缺，包括新添加的数据。
我怀疑需要刷新实时绑定才能将所有数据返回到TListView。
有人对如何在运行时刷新实时绑定有任何想法吗？
P.S。我希望以上内容能清楚地说明我的问题。否则，如果您需要更多详细信息，请告诉我。
更新1：最少可重复的示例
这是我对MRE所做的最少的事情，不是我所遇到的确切情况，但应该是同一问题。在TabItem2上添加列表后，您会注意到，然后回到TabItem1在列表上添加更多项，列表上的现有详细信息将消失。
FMX程序
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文件
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,*;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
解决方法
错误在于我在FDMemTable（mtb3）中创建的Lookup字段。我避免了这些。相反，我创建了一个普通数据字段，并直接从TListView（lsv2）中获取数据，如下所示：
FMX程序
procedure TTabbedwithNavigationForm.btn1Click(Sender: TObject);
var
brandname,brand : string;
begin
brandname := mtb2.Lookup('name',lsv2.Items[lsv2.ItemIndex].Text,'name');
brand := mtb2.Lookup('name','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文件
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
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