Specifies properties of a lookup column.
A lookup column restricts the set of values that can be chosen when a user edits or filters the column. In a lookup column, each cell is a drop-down menu. You can use a lookup column when you need to substitute displayed values with required values. For example, consider that you have two arrays of objects: drivers and buses.
JavaScript
const drivers = [ { driverID: 1, firstName: "John", lastName: "Smith", busID: 2 }, { driverID: 2, firstName: "Lizzy", lastName: "Cook", busID: 1 }, { driverID: 3, firstName: "Brian", lastName: "Hawkins", busID: 3 }];const buses = [ { busID: 1, plates: "123456" }, { busID: 2, plates: "AB-1234" }, { busID: 3, plates: "CD-9876" }];All drivers have the busID field, which refers to a bus. If drivers is the main dataSource, the Bus ID column displays bus IDs, which provides little information to a user. It will be more useful to display bus license plates instead of IDs. For this, the buses array must be set as a lookup dataSource for the Bus ID column. Then, the names of data fields must be assigned to the valueExpr and displayExpr properties. Values from the valueExpr data field will be replaced with values from the displayExpr data field.
jQuery
JavaScript
$(function() { $("#dataGridContainer").dxDataGrid({ dataSource: drivers, // ... columns: [{ dataField: "busID", lookup: { dataSource: buses, valueExpr: "busID", displayExpr: "plates" } }] });});Angular
HTML
TypeScript
<dx-data-grid [dataSource]="drivers"> <dxi-column dataField="busID"> <dxo-lookup [dataSource]="buses" valueExpr="busID" displayExpr="plates"> </dxo-lookup> </dxi-column></dx-data-grid>
import { DxDataGridModule } from "devextreme-angular";// ...export class AppComponent { drivers = [ { driverID: 1, firstName: "John", lastName: "Smith", busID: 2 }, { driverID: 2, firstName: "Lizzy", lastName: "Cook", busID: 1 }, { driverID: 3, firstName: "Brian", lastName: "Hawkins", busID: 3 } ]; buses = [ { busID: 1, plates: "123456" }, { busID: 2, plates: "AB-1234" }, { busID: 3, plates: "CD-9876" } ];}@NgModule({ imports: [ // ... DxDataGridModule ], // ...})Vue
App.vue
<template> <DxDataGrid ... :data-source="drivers"> <DxColumn data-field="busID"> <DxLookup :data-source="buses" value-expr="busID" display-expr="plates" /> </DxColumn> </DxDataGrid></template><script>import 'devextreme/dist/css/dx.light.css';import DxDataGrid, { DxColumn, DxLookup} from 'devextreme-vue/data-grid';const drivers = [ { driverID: 1, firstName: "John", lastName: "Smith", busID: 2 }, { driverID: 2, firstName: "Lizzy", lastName: "Cook", busID: 1 }, { driverID: 3, firstName: "Brian", lastName: "Hawkins", busID: 3 }];const buses = [ { busID: 1, plates: "123456" }, { busID: 2, plates: "AB-1234" }, { busID: 3, plates: "CD-9876" }];export default { components: { DxDataGrid, DxColumn, DxLookup }, data() { return { drivers, buses } }}</script>React
App.js
import React from 'react';import 'devextreme/dist/css/dx.light.css';import DataGrid, { Column, Lookup} from 'devextreme-react/data-grid';const drivers = [ { driverID: 1, firstName: "John", lastName: "Smith", busID: 2 }, { driverID: 2, firstName: "Lizzy", lastName: "Cook", busID: 1 }, { driverID: 3, firstName: "Brian", lastName: "Hawkins", busID: 3 }];const buses = [ { busID: 1, plates: "123456" }, { busID: 2, plates: "AB-1234" }, { busID: 3, plates: "CD-9876" }];export default function App() { return ( <DataGrid ... dataSource={drivers}> <Column dataField="busID"> <Lookup dataSource={buses} valueExpr="busID" displayExpr="plates" /> </Column> </DataGrid> );}With this code, the Bus ID column contains license plates instead of IDs. Moreover, the user can choose a plate number from the drop-down menu when editing cells or applying a filter to this column.
View Demo View on GitHub
See Also
- Bind a Lookup Column to a Custom Data Source
- Customize Editors
- Enhance Performance on Large Datasets - Lookup Optimization
allowClearing
Specifies whether to display the Clear button in lookup column cells while they are being edited.
Type:
Default Value: false
Set this property to true only if your data source accepts null values.
To specify this property based on a condition, set the showClearButton property instead. This is a property of the SelectBox UI component which is used as an editor for lookup column cells. allowClearing is an alias for this property in the DataGrid. The following code shows how to set showClearButton in the onEditorPreparing event handler:
jQuery
index.js
$(function() { $("#dataGridContainer").dxDataGrid({ // ... onEditorPreparing: function (e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } });});Angular
app.component.ts
app.module.ts
app.component.html
import { Component } from '@angular/core';@Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css']})export class AppComponent { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } }}import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { AppComponent } from './app.component';import { DxDataGridModule } from 'devextreme-angular';@NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, DxDataGridModule ], bootstrap: [AppComponent]})export class AppModule { }<dx-data-grid ... (onEditorPreparing)="onEditorPreparing($event)"> <!-- ... --></dx-data-grid>
Vue
App.vue
<template> <DxDataGrid ... :on-editor-preparing="onEditorPreparing"> <!-- ... --> </DxDataGrid></template><script>import 'devextreme/dist/css/dx.light.css';import DxDataGrid from 'devextreme-vue/data-grid';export default { components: { DxDataGrid }, // ... methods: { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } }}</script>React
App.js
import React from 'react';import 'devextreme/dist/css/dx.light.css';import DataGrid from 'devextreme-react/data-grid';class App extends React.Component { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } render() { return ( <DataGrid ... onEditorPreparing={this.onEditorPreparing}> {/* ... */} </DataGrid> ); }}export default App;dataSource
Specifies the data source for the lookup column.
An array of objects or primitives, a store instance, or a DataSource configuration.
Default Value: undefined
This property accepts one of the following:
Array of objects or primitives
A JavaScript array that contains plain objects or primitives.DataSource configuration object
A DataSource configuration object. You can find code for this example in the following help topic: Bind a Lookup Column to a Custom Data Source. For more information about the DataSource and DevExtreme Data Layer, refer to the Data Layer article.IMPORTANT
DataSource instances are not supported.
Store instance
An ArrayStore, LocalStore, ODataStore, or CustomStore instance.Function
A function that returns one of the above.
If the lookup data source contains objects, specify the valueExpr and displayExpr properties in addition to the dataSource.
NOTE
Collections of primitives are not supported if you use the DevExtreme.AspNet.Data library API directly or via a server-side wrapper (as with the DevExtreme ASP.NET MVC Controls) to load the collections from a remote data source. Reconfigure the data source to return collections of objects.
View Demo
displayExpr
Specifies the data source field whose values must be displayed.
Function parameters:
data:
A row's data.
Return Value:
The displayed value.
Default Value: undefined
This property accepts a string - the name of the data field that provides displayed values, or a function that returns the displayed value.
View Demo
NOTE
Values in a lookup column are sorted by the valueExpr field. Implement the column's calculateSortValue function if you want to sort by the displayExpr field instead:
jQuery
index.js
$(function() { $("#dataGridContainer").dxDataGrid({ columns: [{ // ... lookup: { // ... }, calculateSortValue: function (data) { const value = this.calculateCellValue(data); return this.lookup.calculateCellValue(value); } }] });});Angular
app.component.html
app.component.ts
app.module.ts
<dx-data-grid ... > <dxi-column ... [calculateSortValue]="calculateSortValue"> <dxo-lookup ... ></dxo-lookup> </dxi-column></dx-data-grid>
import { Component } from '@angular/core';@Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css']})export class AppComponent { calculateSortValue (data) { const column = this as any; const value = column.calculateCellValue(data); return column.lookup.calculateCellValue(value); }}import { BrowserModule } from '@angular/platform-browser';import { NgModule } from '@angular/core';import { AppComponent } from './app.component';import { DxDataGridModule } from 'devextreme-angular';@NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, DxDataGridModule ], providers: [ ], bootstrap: [AppComponent]})export class AppModule { }Vue
App.vue
<template> <DxDataGrid ... > <DxColumn ... :calculate-sort-value="calculateSortValue"> <DxLookup ... /> </DxColumn> </DxDataGrid></template><script>import 'devextreme/dist/css/dx.light.css';import DxDataGrid, { DxColumn, DxLookup} from 'devextreme-vue/data-grid';export default { components: { DxDataGrid, DxColumn, DxLookup }, data() { return { calculateSortValue (data) { const column = this; const value = column.calculateCellValue(data); return column.lookup.calculateCellValue(value); } } }}</script>React
App.js
import React from 'react';import 'devextreme/dist/css/dx.light.css';import DataGrid, { Column, Lookup} from 'devextreme-react/data-grid';function calculateSortValue (data) { const column = this; const value = column.calculateCellValue(data); return column.lookup.calculateCellValue(value);}export default function App() { return ( <DataGrid ... > <Column ... calculateSortValue={calculateSortValue}> <Lookup ... /> </Column> </DataGrid> );}valueExpr
Specifies the data field whose values should be replaced with values from the displayExpr field.
Type:
Default Value: undefined
Values from this data field must have the same type as the column's dataField values.
View Demo
NOTE
You cannot specify valueExpr as a function when the UI component is bound to a remote data source. This is because valueExpr is used in a filter the UI component sends to the server when querying data. Functions with custom logic cannot be serialized for this filter.
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