Angular Lookup Properties

See Also

• Configure a Widget: Angular | Vue | React | jQuery | AngularJS | Knockout

The value of this property will be passed to the accesskey attribute of the HTML element that underlies the UI component.

This property is used when the UI component is displayed on a platform whose guidelines include the active state change for UI components.

The property accepts the following values.

• "useButtons"
  Enables an end-user to apply the selected value or cancel the selection using the Apply and Cancel buttons respectively.

• "instantly"
  Applies the selected value immediately after a user clicks the required value in the drop-down menu. To cancel the selection, click outside the drop-down menu.

The Lookup works with collections of objects or string, number, or boolean values.

Depending on your data source, bind the Lookup to data as follows. In each case, also specify the valueExpr, displayExpr, or both if the data source provides objects.

• Data Array
  Assign the array to the dataSource option.

• Read-Only Data in JSON Format
  Set the dataSource property to the URL of a JSON file or service that returns JSON data.

• OData
  Implement an ODataStore.

• Web API, PHP, MongoDB
  Use one of the following extensions to enable the server to process data according to the protocol DevExtreme UI components use:

  • DevExtreme.AspNet.Data
  • DevExtreme-PHP-Data
  • devextreme-query-mongodb

  Then, use the createStore method to configure access to the server on the client as shown below. This method is part of DevExtreme.AspNet.Data.

  jQuery

  JavaScript

  $(function() {
      let serviceUrl = "https://url/to/my/service";
      $("#lookupContainer").dxLookup({
          // ...
          dataSource: DevExpress.data.AspNet.createStore({
              key: "ID",
              loadUrl: serviceUrl + "/GetAction",
              insertUrl: serviceUrl + "/InsertAction",
              updateUrl: serviceUrl + "/UpdateAction",
              deleteUrl: serviceUrl + "/DeleteAction"
          })
      })
  });

  Angular

  app.component.ts

  app.component.html

  app.module.ts

  import { Component } from '@angular/core';
  import CustomStore from 'devextreme/data/custom_store';
  import { createStore } from 'devextreme-aspnet-data-nojquery';
  
  @Component({
      selector: 'app-root',
      templateUrl: './app.component.html',
      styleUrls: ['./app.component.css']
  })
  export class AppComponent {
      store: CustomStore;
      constructor() {
          let serviceUrl = "https://url/to/my/service";
          this.store = createStore({
              key: "ID",
              loadUrl: serviceUrl + "/GetAction",
              insertUrl: serviceUrl + "/InsertAction",
              updateUrl: serviceUrl + "/UpdateAction",
              deleteUrl: serviceUrl + "/DeleteAction"
          })
      }
  }

  <dx-lookup ...
      [dataSource]="store">
  </dx-lookup>

  import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { AppComponent } from './app.component';
  
  import { DxLookupModule } from 'devextreme-angular';
  
  @NgModule({
      declarations: [
          AppComponent
      ],
      imports: [
          BrowserModule,
          DxLookupModule
      ],
      providers: [],
      bootstrap: [AppComponent]
  })
  export class AppModule { }

  Vue

  App.vue

  <template> 
      <DxLookup ...
          :data-source="store" />
  </template>
  
  <script>
  import 'devextreme/dist/css/dx.common.css';
  import 'devextreme/dist/css/dx.light.css';
  
  import CustomStore from 'devextreme/data/custom_store';
  import { createStore } from 'devextreme-aspnet-data-nojquery';
  import { DxLookup } from 'devextreme-vue/lookup';
  
  export default {
      components: {
          DxLookup
      },
      data() {
          const serviceUrl = "https://url/to/my/service";
          const store = createStore({
              key: "ID",
              loadUrl: serviceUrl + "/GetAction",
              insertUrl: serviceUrl + "/InsertAction",
              updateUrl: serviceUrl + "/UpdateAction",
              deleteUrl: serviceUrl + "/DeleteAction"
          });
          return {
              store
          }
      }
  }
  </script>

  React

  App.js

  import React from 'react';
  import 'devextreme/dist/css/dx.common.css';
  import 'devextreme/dist/css/dx.light.css';
  
  import CustomStore from 'devextreme/data/custom_store';
  import { createStore } from 'devextreme-aspnet-data-nojquery';
  import Lookup from 'devextreme-react/lookup';
  
  const serviceUrl = "https://url/to/my/service";
  const store = createStore({
      key: "ID",
      loadUrl: serviceUrl + "/GetAction",
      insertUrl: serviceUrl + "/InsertAction",
      updateUrl: serviceUrl + "/UpdateAction",
      deleteUrl: serviceUrl + "/DeleteAction"
  });
  
  class App extends React.Component {
      render() {
          return (
              <Lookup ...
                  dataSource={store} />
          );
      }
  }
  export default App;

• Any other data source
  Implement a CustomStore.

Regardless of the data source on the input, the Lookup always wraps it in the DataSource object. This object allows you to sort, filter, group, and perform other data shaping operations. To get its instance, call the getDataSource() method.

Set this property to the name of a data field that provides displayed values...

displayExpr: "name"

... or to a function that returns the displayed value:

displayExpr: function(item) {
    // "item" can be null
    return item && 'ID: ' + item.id + ', Name: ' + item.name;
}

Leave this property unspecified or set it to this if the data source contains primitives.

See Also

• valueExpr

The value you pass to this property does not affect UI component behavior. Pass an observable variable to this property to get the value currently displayed by the UI component.

The drop-down menu can be displayed under the input field (dropDownCentered is false) or over it and centered on the selected item (dropDownCentered is true). The following live example illustrates the difference:

Refer to the Popover configuration for information on properties that you can specify in this object.

View Demo

See Also

• Customize Item Appearance
• Custom Templates

If this property is set to true, the object assigned to the items property should include key and items properties. The key property specifies the group caption in the list. The items property represents an array listing group items.

View Demo

See Also

• Enable Grouping
• Custom Templates

This property accepts a value of one of the following types:

• Number
  The height in pixels.

• String
  A CSS-accepted measurement of height. For example, "55px", "80%", "inherit".

• Function
  A function returning either of the above. For example:

  JavaScript

  height: function() {
      return window.innerHeight / 1.5;
  }

See Also

• Knockout Only - Validate a View Model
• validationErrors

The items array can contain:

• Objects with fields described in this section
• Objects with any other fields. In this case, specify the itemTemplate.

If you need to update the UI component items, reassign the entire items array as shown in the following example:

lookupInstance.option('items', newItems);

As an alternative to items, you can use the dataSource property. It accepts the DataSource object, whose underlying stores provide an API that allows you to update individual items without reassigning the entire item collection.

View Demo

See Also

• Customize Item Appearance
• Custom Templates

Specify this property if the UI component lies within an HTML form that will be submitted.

The Lookup component evaluates the noDataText property's value. This evaluation, however, makes the Lookup potentially vulnerable to XSS attacks. To guard against these attacks, encode the HTML markup before you assign it to the noDataText property. Refer to the following help topic for more information: Potentially Vulnerable API - noDataText.

If data displayed by the UI component is specified using a DataSource instance, the contentReady event fires each time the load() method of the DataSource instance is called as well as when UI component content is ready. In this case, when you create the UI component, the contentReady event is raised twice: when the UI component's content is ready (at this moment, the UI component does not display items) and when the DataSource is loaded (the UI component displays the loaded items).

See Also

• Get a UI component Instance in Angular | AngularJS | Knockout | Vue | React

The following example shows how to subscribe to component property changes:

$(function() {
    $("#lookupContainer").dxLookup({
        // ...
        onOptionChanged: function(e) {
            if(e.name === "changedProperty") {
                // handle the property change here
            }
        }
    });
});

<dx-lookup ...
    (onOptionChanged)="handlePropertyChange($event)"> 
</dx-lookup>

import { Component } from '@angular/core'; 

@Component({ 
    selector: 'app-root', 
    templateUrl: './app.component.html', 
    styleUrls: ['./app.component.css'] 
}) 

export class AppComponent { 
    // ...
    handlePropertyChange(e) {
        if(e.name === "changedProperty") { 
            // handle the property change here
        }
    }
}

import { BrowserModule } from '@angular/platform-browser'; 
import { NgModule } from '@angular/core'; 
import { AppComponent } from './app.component'; 
import { DxLookupModule } from 'devextreme-angular'; 

@NgModule({ 
    declarations: [ 
        AppComponent 
    ], 
    imports: [ 
        BrowserModule, 
        DxLookupModule 
    ], 
    providers: [ ], 
    bootstrap: [AppComponent] 
}) 

export class AppModule { }  

<template> 
    <DxLookup ...
        @option-changed="handlePropertyChange"
    />            
</template> 

<script> 
import 'devextreme/dist/css/dx.common.css'; 
import 'devextreme/dist/css/dx.light.css'; 
import DxLookup from 'devextreme-vue/lookup'; 

export default { 
    components: { 
        DxLookup
    }, 
    // ...
    methods: { 
        handlePropertyChange: function(e) {
            if(e.name === "changedProperty") {
                // handle the property change here
            }
        }
    } 
} 
</script> 

import React from 'react'; 
import 'devextreme/dist/css/dx.common.css'; 
import 'devextreme/dist/css/dx.light.css'; 

import Lookup from 'devextreme-react/lookup'; 

const handlePropertyChange = (e) => {
    if(e.name === "changedProperty") {
        // handle the property change here
    }
}

export default function App() { 
    return ( 
        <Lookup ...
            onOptionChanged={handlePropertyChange}
        />        
    ); 
} 

See Also

• Enable Paging

View Demo

See Also

• valueChangeEvent

If the property is set to true, the UI component data is refreshed each time you pull down and release UI component contents.

When this property is set to true, the UI component text flows from right to left, and the layout of elements is reversed. To switch the entire application/site to the right-to-left representation, assign true to the rtlEnabled field of the object passed to the DevExpress.config(config) method.

DevExpress.config({
    rtlEnabled: true
});

DataGrid Demo Navigation UI Demo Editors Demo

See Also

• Configure Search Parameters

In most cases, you should pass the name of a field by whose value data items are searched. If you need to search elements by several field values, assign an array of field names to this property.

searchExpr: ["firstName", "lastName"]

For more information on searching, refer to the Search API section of the Data Layer article. For information on getters, refer to the Getters and Setters section of the Data Layer article.

The Cancel button cancels the attempt to change the lookup UI component value.

The Clear button calls the reset method which resets the value property to its default value (null). The lookup window closes and the text specified by the placeholder property is shown in the lookup editor.

If this property is disabled, the UI component does not display values until the number of typed characters exceeds the minSearchLength value, otherwise it displays all values regardless of the specified filtering condition.

The following styles are available:

You can also use the global editorStylingMode setting to specify how the text fields of all editors in your application are styled.

The value of this property will be passed to the tabindex attribute of the HTML element that underlies the UI component.

See Also

• Customize the Drop-Down Menu
• Custom Templates

Lookup contents can be displayed in a Popover only if dropDownOptions.fullScreen is disabled. Otherwise, lookup contents are displayed within the Popup UI component.

Material Design themes always use the Popup UI component, ignoring the usePopover property.

See Also

• isValid

The following property values are possible:

• auto
  The tooltip with the message is displayed when the editor is in focus.
• always
  The tooltip with the message is not hidden when the editor loses focus.

The following table illustrates the validation status indicators:

validationStatus	Indicator
"pending"
"valid"
"invalid"

View Demo

This property accepts a single event name or several names separated by spaces.

The recommended events are "keyup", "blur", "change", "input", and "focusout", but you can use other events as well.

See Also

• onValueChanged

Always set this property if the dataSource contains objects. Alternatively, you can specify the key in the store.

See Also

• displayExpr

This property accepts a value of one of the following types:

• Number
  The width in pixels.

• String
  A CSS-accepted measurement of width. For example, "55px", "80%", "auto", "inherit".

• Function
  A function returning either of the above. For example:

  JavaScript

  width: function() {
      return window.innerWidth / 1.5;
  }