TcxDataSummaryItems Class
The base class for summary item collections.
#Declaration
TcxDataSummaryItems = class(
TcxCollection
)
#Remarks
A summary controller uses summary item collections to manage group and footer summaries.
#Main API Members
The list below outlines key members of the TcxDataSummaryItems
class. These members allow you to manage and configure summary items.
#Collection Management APIs
- Add
- Creates a new summary item and adds it to the collection.
- Clear
- Clears the collection.
- Count
- Returns the number of stored summary items.
- Delete | DeleteItems
- Delete individual summary items.
- FindByTag
- Returns the first summary item in the collection with the specified tag.
- Items
- Provides indexed access to summary items in the collection.
#Summary-Related APIs
- DefaultFormat
- Returns the default formatting pattern for the summary item with the specified data type, position, and calculation algorithm.
- OnSummary
- Allows you to customize summary calculation.
#General-Purpose API Members
- Assign
- Copies settings and stored items between summary item collections.
- BeginUpdate | EndUpdate
- Allow you to avoid excessive notifications and corresponding redraw operations during batch collection changes.
- DataController | Summary
- Provide access to parent data and summary controllers.
#Terminal TcxDataSummaryItems Class Descendants
Do not use the TcxDataSummaryItems
class directly. Use the following descendants instead:
- TcxDataFooterSummaryItems
- A collection of footer summaries.
- TcxDataGroupSummaryItems
- A collection of group summaries.
#Indirect TcxDataSummaryItems Class Reference
The TcxDataSummaryItem.SummaryItems property references the TcxDataFooterSummaryItems or TcxDataGroupSummaryItems class as a TcxDataSummaryItems
object.
#Code Example: Create and Display Three Footer Summaries
The code example in this section creates and displays three summary items for the same column. These items use three different predefined summary calculation algorithms – SUM, MAX, and MIN.
Follow the steps below to test this code example in your RAD Studio IDE:
- Copy the DFM code snippet below.
- Create a new project in the IDE and focus an empty form.
- Press Ctrl+V to populate the form with preconfigured components.
- Select the form and create an empty OnCreate event handler, paste the code example, and run the project.
object cxGrid1: TcxGrid
Left = 72
Top = 80
Width = 425
Height = 321
TabOrder = 0
object cxGrid1DBTableView1: TcxGridDBTableView
Navigator.Buttons.CustomButtons = <>
ScrollbarAnnotations.CustomAnnotations = <>
DataController.DataSource = DataSource1
DataController.Summary.DefaultGroupSummaryItems = <>
DataController.Summary.FooterSummaryItems = <>
DataController.Summary.SummaryGroups = <>
object cxGrid1DBTableView1RecId: TcxGridDBColumn
DataBinding.FieldName = 'RecId'
Visible = False
end
object cxGrid1DBTableView1Groups: TcxGridDBColumn
DataBinding.FieldName = 'Groups'
end
object cxGrid1DBTableView1Names: TcxGridDBColumn
DataBinding.FieldName = 'Names'
end
object cxGrid1DBTableView1Values: TcxGridDBColumn
DataBinding.FieldName = 'Values'
Width = 175
end
end
object cxGrid1Level1: TcxGridLevel
GridView = cxGrid1DBTableView1
end
end
object dxMemData1: TdxMemData
Active = True
Indexes = <>
Persistent.Data = {
5665728FC2F5285C8FFE3F04000000140000000100070047726F757073001400
0000010006004E616D657300040000000300070056616C756573000400000009
000600446174657300010600000047726F75703101050000004E616D6531010A
000000017B000B00010600000047726F75703101050000004E616D6532011400
000001CF0E0B00010600000047726F75703201050000004E616D6533011E0000
00017A210B00010600000047726F75703201050000004E616D65340128000000
01892B0B00}
SortOptions = []
Left = 248
Top = 336
object dxMemData1Groups: TStringField
FieldName = 'Groups'
end
object dxMemData1Names: TStringField
FieldName = 'Names'
end
object dxMemData1Values: TIntegerField
FieldName = 'Values'
end
object dxMemData1Dates: TDateField
FieldName = 'Dates'
end
end
object DataSource1: TDataSource
DataSet = dxMemData1
Left = 152
Top = 320
end
object dxSkinController1: TdxSkinController
SkinName = 'WXICompact'
SkinPaletteName = 'Office Dark Gray'
Left = 64
Top = 320
end
procedure TMyForm.FormCreate(Sender: TObject);
var
ASummary: TcxDataSummary;
ASummaryItem: TcxGridDBTableSummaryItem;
begin
cxGrid1DBTableView1.OptionsView.Footer := True; // Displays a footer
cxGrid1DBTableView1.OptionsView.FooterMultiSummaries := True; // Allows the footer to fit all summaries
ASummary := cxGrid1DBTableView1.DataController.Summary;
ASummary.BeginUpdate; // Initiates the following batch change
try
// Create three summary items
ASummaryItem := ASummary.FooterSummaryItems.Add as TcxGridDBTableSummaryItem;
ASummaryItem.Column := cxGrid1DBTableView1Values; // Associates the summary with the "Values" column
ASummaryItem.Kind := skSum; // Sums all values in the target column
ASummaryItem := ASummary.FooterSummaryItems.Add as TcxGridDBTableSummaryItem;
ASummaryItem.Column := cxGrid1DBTableView1Values; // Associates the summary with the "Values" column
ASummaryItem.Kind := skMax; // Displays the highest value in the target column
ASummaryItem := ASummary.FooterSummaryItems.Add as TcxGridDBTableSummaryItem;
ASummaryItem.Column := cxGrid1DBTableView1Values; // Associates the summary with the "Values" column
ASummaryItem.Kind := skMin; // Displays the minimum value in the target column
finally
ASummary.EndUpdate; // Calls EndUpdate regardless of the batch operation's success
end;
end;
#Related Compiled Demo
To see group and footer summaries in action, run the Grid and Data Editors demo in the VCL Demo Center installed with compiled DevExpress demos. Click Data Summaries or Advanced Data Filtering in the sidebar to select the corresponding VCL Data Grid demo.
Tip
Compiled DevExpress demos ship with source code installed in the Public Documents folder (%Public%) for all users (default). You can find all project and source code files for the Data Grid demo in the following folder:
%Public%\Documents\DevExpress VCL Demos\Mega