JavaScript/jQuery Gantt - columns.lookup
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
.
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
$(function() { $("#ganttContainer").dxGantt({ dataSource: drivers, // ... columns: [{ dataField: "busID", lookup: { dataSource: buses, valueExpr: "busID", displayExpr: "plates" } }] }); });
Angular
<dx-gantt [dataSource]="drivers"> <dxi-column dataField="busID"> <dxo-lookup [dataSource]="buses" valueExpr="busID" displayExpr="plates"> </dxo-lookup> </dxi-column> </dx-gantt>
import { DxGanttModule } 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: [ // ... DxGanttModule ], // ... })
Vue
<template> <DxGantt ... :data-source="drivers"> <DxColumn data-field="busID"> <DxLookup :data-source="buses" value-expr="busID" display-expr="plates" /> </DxColumn> </DxGantt> </template> <script> import 'devextreme/dist/css/dx.light.css'; import DxGantt, { DxColumn, DxLookup } from 'devextreme-vue/gantt'; 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: { DxGantt, DxColumn, DxLookup }, data() { return { drivers, buses } } } </script>
React
import React from 'react'; import 'devextreme/dist/css/dx.light.css'; import Gantt, { Column, Lookup } from 'devextreme-react/gantt'; 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 ( <Gantt ... dataSource={drivers}> <Column dataField="busID"> <Lookup dataSource={buses} valueExpr="busID" displayExpr="plates" /> </Column> </Gantt> ); }
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.
See Also
allowClearing
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 Gantt. The following code shows how to set showClearButton in the onEditorPreparing event handler:
jQuery
$(function() { $("#ganttContainer").dxGantt({ // ... onEditorPreparing: function (e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } }); });
Angular
import { Component } from '@angular/core'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } }
import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { AppComponent } from './app.component'; import { DxGanttModule } from 'devextreme-angular'; @NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, DxGanttModule ], bootstrap: [AppComponent] }) export class AppModule { }
<dx-gantt ... (onEditorPreparing)="onEditorPreparing($event)"> <!-- ... --> </dx-gantt>
Vue
<template> <DxGantt ... :on-editor-preparing="onEditorPreparing"> <!-- ... --> </DxGantt> </template> <script> import 'devextreme/dist/css/dx.light.css'; import DxGantt from 'devextreme-vue/gantt'; export default { components: { DxGantt }, // ... methods: { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } } } </script>
React
import React from 'react'; import 'devextreme/dist/css/dx.light.css'; import Gantt from 'devextreme-react/gantt'; class App extends React.Component { onEditorPreparing(e) { if (/* a condition to set the property's value */) { e.editorOptions.showClearButton = true; } } render() { return ( <Gantt ... onEditorPreparing={this.onEditorPreparing}> {/* ... */} </Gantt> ); } } export default App;
dataSource
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.IMPORTANTDataSource 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.
displayExpr
This property accepts a string - the name of the data field that provides displayed values, or a function that returns the displayed value.
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
$(function() { $("#ganttContainer").dxGantt({ columns: [{ // ... lookup: { // ... }, calculateSortValue: function (data) { const value = this.calculateCellValue(data); return this.lookup.calculateCellValue(value); } }] }); });
Angular
<dx-gantt ... > <dxi-column ... [calculateSortValue]="calculateSortValue"> <dxo-lookup ... ></dxo-lookup> </dxi-column> </dx-gantt>
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 { DxGanttModule } from 'devextreme-angular'; @NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, DxGanttModule ], providers: [ ], bootstrap: [AppComponent] }) export class AppModule { }
Vue
<template> <DxGantt ... > <DxColumn ... :calculate-sort-value="calculateSortValue"> <DxLookup ... /> </DxColumn> </DxGantt> </template> <script> import 'devextreme/dist/css/dx.light.css'; import DxGantt, { DxColumn, DxLookup } from 'devextreme-vue/gantt'; export default { components: { DxGantt, DxColumn, DxLookup }, data() { return { calculateSortValue (data) { const column = this; const value = column.calculateCellValue(data); return column.lookup.calculateCellValue(value); } } } } </script>
React
import React from 'react'; import 'devextreme/dist/css/dx.light.css'; import Gantt, { Column, Lookup } from 'devextreme-react/gantt'; function calculateSortValue (data) { const column = this; const value = column.calculateCellValue(data); return column.lookup.calculateCellValue(value); } export default function App() { return ( <Gantt ... > <Column ... calculateSortValue={calculateSortValue}> <Lookup ... /> </Column> </Gantt> ); }
valueExpr
Specifies the data field whose values should be replaced with values from the displayExpr field.
Values from this data field must have the same type as the column's dataField values.
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