TreeListColumn.UnboundExpression Property
Gets or sets an expression used to evaluate values for the current unbound column.
Namespace: DevExpress.XtraTreeList.Columns
Assembly: DevExpress.XtraTreeList.v23.2.dll
NuGet Packages: DevExpress.Win.Navigation, DevExpress.Win.TreeList
Declaration
[DefaultValue("")]
[DXCategory("Data")]
[XtraSerializableProperty]
public string UnboundExpression { get; set; }Property Value
| Type | Default | Description |
|---|---|---|
| String | String.Empty | A String that specifies an expression used to evaluate values for this column. |
Remarks
Unbound columns can be populated with the TreeList.CustomUnboundColumnData event, or by setting the UnboundExpression property to a string expression used to evaluate values for the current column. The Expressions section describes the syntax for creating expressions.
When using expressions, data entered by end-users cannot be saved. To save data, use the TreeList.CustomUnboundColumnData event.
If the TreeListColumn.ShowUnboundExpressionMenu option is enabled, an end-user can edit a column expression via the Expression Editor at runtime. See TreeListColumn.ShowUnboundExpressionMenu, for more information.
Example
The following example creates a TreeList at runtime and shows how to perform basic customization tasks:
- Bind the treelist to a data source
- Specify the key fields that form a hierarchy
- Access automatically created columns
- Set a custom row height
- Customize column captions (using HTML tags) and cell appearance settings
- Create unbound columns and create Excel-style format conditions based on these column values
- Assign an in-place editor (a spin editor) to columns
- Sort data
- Calculate total summaries
- Filter nodes
- Hide columns and calculate column “best” widths
- Locate and expand nodes
- Focus a specific cell
- Specify DataAnnotation attributes at the data source level (the “p0” display format for the MarketShare field)
using DevExpress.XtraEditors;
using DevExpress.XtraEditors.Repository;
using DevExpress.XtraTreeList;
using DevExpress.XtraTreeList.Columns;
using DevExpress.XtraTreeList.Nodes;
using DevExpress.XtraTreeList.StyleFormatConditions;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Windows.Forms;
namespace TreeList_example {
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e) {
TreeList treeList1 = new TreeList();
treeList1.Parent = this;
treeList1.Dock = DockStyle.Fill;
//Specify the fields that arrange underlying data as a hierarchy.
treeList1.KeyFieldName = "ID";
treeList1.ParentFieldName = "RegionID";
//Allow the treelist to create columns bound to the fields the KeyFieldName and ParentFieldName properties specify.
treeList1.OptionsBehavior.PopulateServiceColumns = true;
//Specify the data source.
treeList1.DataSource = SalesDataGenerator.CreateData();
//The treelist automatically creates columns for the public fields found in the data source.
//You do not need to call the TreeList.PopulateColumns method unless the treeList1.OptionsBehavior.AutoPopulateColumns option is disabled.
//Change the row height.
treeList1.RowHeight = 23;
//Access the automatically created columns.
TreeListColumn colRegion = treeList1.Columns["Region"];
TreeListColumn colMarchSales = treeList1.Columns["MarchSales"];
TreeListColumn colSeptemberSales = treeList1.Columns["SeptemberSales"];
TreeListColumn colMarchSalesPrev = treeList1.Columns["MarchSalesPrev"];
TreeListColumn colSeptemberSalesPrev = treeList1.Columns["SeptemberSalesPrev"];
TreeListColumn colMarketShare = treeList1.Columns["MarketShare"];
//Hide the key columns. An end user can access them from the Customization Form.
treeList1.Columns[treeList1.KeyFieldName].Visible = false;
treeList1.Columns[treeList1.ParentFieldName].Visible = false;
//Format column headers and cell values.
colMarchSalesPrev.Caption = "<i>Previous <b>March</b> Sales</i>";
colSeptemberSalesPrev.Caption = "<i>Previous <b>September</b> Sales</i>";
treeList1.OptionsView.AllowHtmlDrawHeaders = true;
colMarchSalesPrev.AppearanceCell.Font = new System.Drawing.Font(colMarchSalesPrev.AppearanceCell.Font, System.Drawing.FontStyle.Italic);
colSeptemberSalesPrev.AppearanceCell.Font = new System.Drawing.Font(colSeptemberSalesPrev.AppearanceCell.Font, System.Drawing.FontStyle.Italic);
//Create two hidden unbound columns that calculate their values from expressions.
TreeListColumn colUnboundMarchChange = treeList1.Columns.AddField("FromPrevMarchChange");
colUnboundMarchChange.Caption = "Change from prev March";
colUnboundMarchChange.UnboundDataType = typeof(decimal);
colUnboundMarchChange.UnboundExpression = "[MarchSales]-[MarchSalesPrev]";
TreeListColumn colUnboundSeptemberChange = treeList1.Columns.AddField("FromPrevSepChange");
colUnboundSeptemberChange.Caption = "Change from prev September";
colUnboundSeptemberChange.UnboundDataType = typeof(decimal);
colUnboundSeptemberChange.UnboundExpression = "[SeptemberSales]-[SeptemberSalesPrev]";
colUnboundMarchChange.OptionsColumn.ShowInCustomizationForm = false;
colUnboundSeptemberChange.OptionsColumn.ShowInCustomizationForm = false;
//Make the Region column read-only.
colRegion.OptionsColumn.ReadOnly = true;
//Sort data against the Region column.
colRegion.SortIndex = 0;
//Apply a filter.
treeList1.ActiveFilterString = "[MarchSales] > 10000";
//Calculate two total summaries against root nodes.
colMarchSales.SummaryFooter = DevExpress.XtraTreeList.SummaryItemType.Sum;
colMarchSales.SummaryFooterStrFormat = "Total={0:c0}";
colMarchSales.AllNodesSummary = false;
colSeptemberSales.SummaryFooter = DevExpress.XtraTreeList.SummaryItemType.Sum;
colSeptemberSales.SummaryFooterStrFormat = "Total={0:c0}";
colSeptemberSales.AllNodesSummary = false;
treeList1.OptionsView.ShowSummaryFooter = true;
//Use a 'SpinEdit' in-place editor for the 'sales' columns.
RepositoryItemSpinEdit riSpinEdit = new RepositoryItemSpinEdit();
riSpinEdit.DisplayFormat.FormatType = DevExpress.Utils.FormatType.Numeric;
riSpinEdit.DisplayFormat.FormatString = "c0";
treeList1.RepositoryItems.Add(riSpinEdit);
colMarchSales.ColumnEdit = riSpinEdit;
colMarchSalesPrev.ColumnEdit = riSpinEdit;
colSeptemberSales.ColumnEdit = riSpinEdit;
colSeptemberSalesPrev.ColumnEdit = riSpinEdit;
//Apply Excel-style formatting: display predefined 'Up Arrow' and 'Down Arrow' icons based on the unbound column values.
TreeListFormatRule rule1 = new TreeListFormatRule();
rule1.Rule = createThreeTrianglesIconSetRule();
rule1.Column = colUnboundMarchChange;
rule1.ColumnApplyTo = colMarchSales;
TreeListFormatRule rule2 = new TreeListFormatRule();
rule2.Rule = createThreeTrianglesIconSetRule();
rule2.Column = colUnboundSeptemberChange;
rule2.ColumnApplyTo = colSeptemberSales;
treeList1.FormatRules.Add(rule1);
treeList1.FormatRules.Add(rule2);
//Do not stretch columns to the treelist width.
treeList1.OptionsView.AutoWidth = false;
//Locate a node by a value it contains.
TreeListNode node1 = treeList1.FindNodeByFieldValue("Region", "North America");
//Focus and expand this node.
treeList1.FocusedNode = node1;
node1.Expanded = true;
//Locate a node by its key field value and expand it.
TreeListNode node2 = treeList1.FindNodeByKeyID(32);//Node 'Asia'
node2.Expand();
//Calculate the optimal column widths after the treelist is shown.
this.BeginInvoke(new MethodInvoker(delegate {
treeList1.BestFitColumns();
}));
}
FormatConditionRuleIconSet createThreeTrianglesIconSetRule() {
FormatConditionRuleIconSet ruleIconSet = new FormatConditionRuleIconSet();
FormatConditionIconSet iconSet = ruleIconSet.IconSet = new FormatConditionIconSet();
FormatConditionIconSetIcon icon1 = new FormatConditionIconSetIcon();
FormatConditionIconSetIcon icon2 = new FormatConditionIconSetIcon();
FormatConditionIconSetIcon icon3 = new FormatConditionIconSetIcon();
//Choose predefined icons.
icon1.PredefinedName = "Triangles3_3.png";
icon2.PredefinedName = "Triangles3_2.png";
icon3.PredefinedName = "Triangles3_1.png";
//Specify the type of threshold values.
iconSet.ValueType = FormatConditionValueType.Number;
//Define ranges to which icons are applied by setting threshold values.
icon1.Value = Decimal.MinValue;
icon1.ValueComparison = FormatConditionComparisonType.GreaterOrEqual;
icon2.Value = 0;
icon2.ValueComparison = FormatConditionComparisonType.GreaterOrEqual;
icon3.Value = 0;
icon3.ValueComparison = FormatConditionComparisonType.Greater;
//Add icons to the icon set.
iconSet.Icons.Add(icon1);
iconSet.Icons.Add(icon2);
iconSet.Icons.Add(icon3);
return ruleIconSet;
}
}
public class SalesData {
static int UniqueID = 37;
public SalesData() {
ID = UniqueID++;
}
public SalesData(int id, int regionId, string region, decimal marchSales, decimal septemberSales, decimal marchSalesPrev, decimal septermberSalesPrev, double marketShare) {
ID = id;
RegionID = regionId;
Region = region;
MarchSales = marchSales;
SeptemberSales = septemberSales;
MarchSalesPrev = marchSalesPrev;
SeptemberSalesPrev = septermberSalesPrev;
MarketShare = marketShare;
}
public int ID { get; set; }
public int RegionID { get; set; }
public string Region { get; set; }
public decimal MarchSales { get; set; }
public decimal SeptemberSales { get; set; }
public decimal MarchSalesPrev { get; set; }
public decimal SeptemberSalesPrev { get; set; }
[DisplayFormat(DataFormatString = "p0")]
public double MarketShare { get; set; }
}
public class SalesDataGenerator {
public static List<SalesData> CreateData() {
List<SalesData> sales = new List<SalesData>();
sales.Add(new SalesData(0, -1, "Western Europe", 30540, 33000, 32220, 35500, .70));
sales.Add(new SalesData(1, 0, "Austria", 22000, 28000, 26120, 28500, .92));
sales.Add(new SalesData(2, 0, "France", 23020, 27000, 20120, 29200, .51));
sales.Add(new SalesData(3, 0, "Germany", 30540, 33000, 32220, 35500, .93));
sales.Add(new SalesData(4, 0, "Spain", 12900, 10300, 14300, 9900, .82));
sales.Add(new SalesData(5, 0, "Switzerland", 9323, 10730, 7244, 9400, .14));
sales.Add(new SalesData(6, 0, "United Kingdom", 14580, 13967, 15200, 16900, .91));
sales.Add(new SalesData(17, -1, "Eastern Europe", 22500, 24580, 21225, 22698, .62));
sales.Add(new SalesData(18, 17, "Belarus", 7315, 18800, 8240, 17480, .34));
sales.Add(new SalesData(19, 17, "Bulgaria", 6300, 2821, 5200, 10880, .8));
sales.Add(new SalesData(20, 17, "Croatia", 4200, 3890, 3880, 4430, .29));
sales.Add(new SalesData(21, 17, "Russia", 22500, 24580, 21225, 22698, .85));
sales.Add(new SalesData(26, -1, "North America", 31400, 32800, 30300, 31940, .84));
sales.Add(new SalesData(27, 26, "USA", 31400, 32800, 30300, 31940, .87));
sales.Add(new SalesData(28, 26, "Canada", 25390, 27000, 5200, 29880, .64));
sales.Add(new SalesData(29, -1, "South America", 16380, 17590, 15400, 16680, .32));
sales.Add(new SalesData(30, 29, "Argentina", 16380, 17590, 15400, 16680, .88));
sales.Add(new SalesData(31, 29, "Brazil", 4560, 9480, 3900, 6100, .10));
sales.Add(new SalesData(32, -1, "Asia", 20388, 22547, 22500, 25756, .52));
sales.Add(new SalesData(34, 32, "India", 4642, 5320, 4200, 6470, .44));
sales.Add(new SalesData(35, 32, "Japan", 9457, 12859, 8300, 8733, .70));
sales.Add(new SalesData(36, 32, "China", 20388, 22547, 22500, 25756, .82));
return sales;
}
}
}
See Also