lookup

Specifies options of a lookup column.

Type:

Object

Default Value: undefined

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
var 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 }
];

var 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 options. 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
    ],
    // ...
})

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

See Also

allowClearing

Specifies whether a user can nullify values of the lookup column.

Type:

Boolean

Default Value: false

Set this option to true only if your data source accepts null values. If you do, all cells of the lookup column in the editing state will have a button that nullifies the cell's value.

dataSource

Specifies the data source for the lookup column.

Function parameters:
options:

Object

Information on the current row.

Object structure:
data:

Object

The row's data.

key: any

The row's key.

Return Value:

Array<any>

|

DataSource Configuration

|

Store

An array of objects or primitives, a store instance, or a DataSource configuration.

Default Value: undefined

This option accepts one of the following:

If the lookup data source contains objects, specify the valueExpr and displayExpr options in addition to the dataSource.

NOTE
Collections of primitives are not supported if they are loaded from a remote data source by using the DevExtreme.AspNet.Data library API either directly or via a server-side wrapper, as done in the DevExtreme ASP.NET MVC Controls. Reconfigure the remote data source to return collections of objects.

View Demo

See Also

displayExpr

Specifies the data source field whose values must be displayed.

Type:

String

|

Function

Function parameters:
data:

Object

A row's data.

Default Value: undefined

This option accepts a string - the name of the data field that provides displayed values, or a function that returns the displayed value.

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
JavaScript
columns: [{
    // ...
    lookup: {
        // ...
    },
    calculateSortValue: function (data) {
        var value = this.calculateCellValue(data);
        return this.lookup.calculateCellValue(value);
    }
}]
Angular
HTML
TypeScript
<dxi-column
    ...
    [calculateSortValue]="calculateSortValue">
    <dxo-lookup ... ></dxo-lookup>
</dxi-column>
export class AppComponent {
    calculateSortValue (data) {
        let column = this as any;
        let value = column.calculateCellValue(data);
        return column.lookup.calculateCellValue(value);
    }
}

valueExpr

Specifies the data source field whose values must be replaced.

Type:

String

Default Value: undefined

Values from this field will be replaced with values from the displayExpr field.

NOTE
You cannot specify valueExpr as a function when the widget is bound to a remote data source. This is because valueExpr is used in a filter the widget sends to the server when querying data. Functions with custom logic cannot be serialized for this filter.