Angular Lookup Properties

See Also

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

The UI component switches to the active state when users press down the primary mouse button. When this property is set to true, the CSS rules for the active state apply. You can change these rules to customize the component.

Use this property when you display the component 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 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.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.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", "20vh", "80%", "inherit".

• Function (deprecated since v21.2)
  Refer to the W0017 warning description for information on how you can migrate to viewport units.

$(function(){
    $("#lookupContainer").dxLookup({
        // ...
        inputAttr: {
            id: "inputId"
        }
    });
});

<dx-lookup ...
    [inputAttr]="{ id: 'inputId' }">
</dx-lookup>

import { DxLookupModule } from "devextreme-angular";
// ...
export class AppComponent {
    // ...
}
@NgModule({
    imports: [
        // ...
        DxLookupModule
    ],
    // ...
})

<template>
    <DxLookup
        :input-attr="inputAttr"
    />
</template>

<script>
import 'devextreme/dist/css/dx.light.css';

import DxLookup from 'devextreme-vue/lookup';

export default {
    components: {
        DxLookup
    },
    data() {
        return {
            inputAttr: { id: 'inputId' }
        }
    }
}
</script>

import 'devextreme/dist/css/dx.light.css';

import Lookup from 'devextreme-react/lookup';

const inputAttr = { id: 'inputId' };

export default function App() {
    return (
        <Lookup
            inputAttr={inputAttr}
        />
    );
}

@(Html.DevExtreme().Lookup()
    .InputAttr("id", "inputId")
    // ===== or =====
    .InputAttr(new {
        @id = "inputId"
    })
    // ===== or =====
    .InputAttr(new Dictionary<string, object>() {
        { "id", "inputId" }
    })
)

@(Html.DevExtreme().Lookup() _
    .InputAttr("id", "inputId")
    ' ===== or =====
    .InputAttr(New With {
        .id = "inputId"
    })
    ' ===== or =====
    .InputAttr(New Dictionary(Of String, Object) From {
        { "id", "inputId" }
    })
)

To improve accessibility, use this property to specify aria-label for the component.

$(function(){
    $("#lookupContainer").dxLookup({
        // ...
        inputAttr: {
            'aria-label': 'your-label',
        },
    });
});

<dx-lookup ...
    [inputAttr]="{ 'aria-label': 'your-label' }">
</dx-lookup>

<template>
    <DxLookup
        :input-attr="inputAttr"
    />
</template>

<script>
import DxLookup from 'devextreme-vue/lookup';

export default {
    components: {
        DxLookup
    },
    data() {
        return {
            inputAttr: { 'aria-label': 'your-label' }
        }
    }
}
</script>

import Lookup from 'devextreme-react/lookup';

const inputAttr = { 'aria-label': 'your-label' };

export default function App() {
    return (
        <Lookup
            inputAttr={inputAttr}
        />
    );
}

You do not need to specify aria-label if you use label.

This property is a read-only flag. You can use it to check if the editor value changed.

$(() => {
    const lookup = $('#lookup').dxLookup({
        // ...
    }).dxLookup('instance');

    $('#button').dxButton({
        // ...
        onClick () {
            if (lookup.option('isDirty')) {
                DevExpress.ui.notify("Do not forget to save changes", "warning", 500);
            }
        }
    });
});

import { Component, ViewChild } from '@angular/core';
import { DxLookupComponent, DxButtonModule } from 'devextreme-angular';
import notify from 'devextreme/ui/notify';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
    @ViewChild('lookupRef', { static: false }) lookup: DxLookupComponent;

    onClick () {
        if (this.lookup.instance.option('isDirty')) {
            notify("Do not forget to save changes", "warning", 500);
        }
    }
}

<dx-lookup ... 
    #lookupRef
>
</dx-lookup>
<dx-button ...
    (onClick)="onClick($event)"
>
</dx-button>

<template>
    <DxLookup ...
        :ref="lookupRef"
    >
    </DxLookup>
    <DxButton ...
        @click="onClick"
    />
</template>

<script>
import 'devextreme/dist/css/dx.light.css';
import DxLookup from 'devextreme-vue/lookup';
import DxButton from 'devextreme-vue/button';
import notify from 'devextreme/ui/notify';

export default {
    components: {
        DxLookup,
        DxButton
    },

    data() {
        return {
            lookupRef
        }
    },

    methods: {
        onClick () {
            if (this.lookup.option('isDirty')) {
                notify("Do not forget to save changes", "warning", 500);
            }
        }
    },

    computed: {
        lookup: function() {
            return this.$refs[lookupRef].instance;
        }
    }
}
</script>

import React, { useRef } from 'react';
import Lookup from 'devextreme-react/lookup';
import Button from 'devextreme-react/button';
import 'devextreme/dist/css/dx.light.css';

const App = () => {
    const lookupRef = useRef(null);

    const onClick = () => {
        if (this.lookupRef.current.instance().option('isDirty')) {
            notify("Do not forget to save changes", "warning", 500);
        }
    };

    return (
        <Lookup ...
            ref={lookupRef}
        >
        </Lookup>
        <Button ...
            onClick={onClick}
        />
    );
};

export default App;

See Also

• reset

See Also

• 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

See Also

• labelMode
• placeholder

This property can have one of the following values:

See Also

• showDataBeforeSearch

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.

<dx-lookup ...
    (onInitialized)="saveInstance($event)">
</dx-lookup>

import { Component } from "@angular/core";
import Lookup from "devextreme/ui/data_grid";
// ...
export class AppComponent {
    lookupInstance: Lookup;
    saveInstance (e) {
        this.lookupInstance = e.component;
    }
}

<template>
    <div>
        <DxLookup ...
            @initialized="saveInstance">
        </DxLookup>
    </div>
</template>

<script>
import DxLookup from 'devextreme-vue/lookup';

export default {
    components: {
        DxLookup
    },
    data: function() {
        return {
            lookupInstance: null
        };
    },
    methods: {
        saveInstance: function(e) {
            this.lookupInstance = e.component;
        }
    }
};
</script>

<template>
    <div>
        <DxLookup ...
            @initialized="saveInstance">
        </DxLookup>
    </div>
</template>

<script setup>
import DxLookup from 'devextreme-vue/lookup';

let lookupInstance = null;

const saveInstance = (e) => {
    lookupInstance = e.component;
}
</script>

import Lookup from 'devextreme-react/lookup';

class App extends React.Component {
    constructor(props) {
        super(props);

        this.saveInstance = this.saveInstance.bind(this);
    }

    saveInstance(e) {
        this.lookupInstance = e.component;
    }

    render() {
        return (
            <div>
                <Lookup onInitialized={this.saveInstance} />
            </div>
        );
    }
}

See Also

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.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.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 Pagination

View Demo

See Also

• valueChangeEvent

See Also

• label

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

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.

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.

$(function() {
    $("#lookup").dxLookup({
        // ...
        searchStartEvent: 'change'
    });
});

<dx-lookup ...
    searchStartEvent="change"
</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 { }  

<template> 
    <DxLookup ...
        search-start-event="change"
    />            
</template> 

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

export default { 
    components: { 
        DxLookup
    }
} 
</script> 

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

import Lookup from 'devextreme-react/lookup'; 

export default function App() { 
    return ( 
        <Lookup ...
            searchStartEvent="change"
        />        
    ); 
} 

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.

If the property is set to true, the text that items within the Lookup contain is passed to the title attribute of the respective item.

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.

If you set this property to auto, the component specifies the validation message position automatically.

The following example positions a validation message at the component's right:

$(function() {
    $("#lookupContainer").dxLookup({
        // ...
        validationMessagePosition: 'right'
    }).dxValidator({
        validationRules: [{
            type: 'required',
            message: 'Required',
        }],
    });
});

<dx-lookup ...
    validationMessagePosition="right">
    <dx-validator>
        <dxi-validation-rule
            type="required"
            message="Required"
        >
        </dxi-validation-rule>
    </dx-validator>
</dx-lookup>

<template>
    <DxLookup ...
        validation-message-position="right"
    >
        <DxValidator>
            <DxRequiredRule message="Required" />
        </DxValidator>
    </DxLookup>
</template>

<script>
    // ...
</script>

import React from 'react';
// ...

function App() {
    return (
        <Lookup ...
            validationMessagePosition="right"
        >
            <Validator>
                <RequiredRule message="Required" />
            </Validator>
        </Lookup>
    ); 

};
export default App;

The following table illustrates the validation status indicators:

validationStatus	Indicator
"pending"
"valid"
"invalid"

When you assign "invalid" to validationStatus, you can also use the validationErrors array to set an error message as shown below:

$(function() {
    const lookup = $("#lookupContainer").dxLookup({
        // ...
    }).dxLookup("instance");

    function setInvalidStatus(message) {
        lookup.option({
            validationStatus: "invalid",
            validationErrors: [{ message: message }]
        });
    }
});

<dx-lookup
    [validationStatus]="validationStatus"
    [validationErrors]="validationErrors">
</dx-lookup>

// ...
export class AppComponent {
    validationStatus: string = "valid";
    validationErrors: any;
    // ...
    setInvalidStatus(message) {
        this.validationStatus = "invalid";
        this.validationErrors = [{ message: message }];
    }
}

<template>
    <DxLookup ...
        :validation-status="validationStatus"
        :validation-errors="validationErrors"
    />
</template>

<script>
    // ...
    export default {
        // ...
        data() {
            return {
                validationStatus: "valid",
                validationErrors: []
            }
        },
        methods: {
            setInvalidStatus(message) {
                this.validationStatus = "invalid";
                this.validationErrors = [{ message: message }];
            }
        }
    }
</script>

import React, { useState } from 'react';
// ...

function App() {
    const [validationStatus, setValidationStatus] = useState("valid");
    const [validationErrors, setValidationErrors] = useState([]);

    const setInvalidStatus = message => {
        setValidationStatus("invalid");
        setValidationErrors([{ message: message }]);
    }

    return (
        <Lookup
            validationStatus={validationStatus}
            validationErrors={validationErrors}
        />
    ); 

};
export default App;

When dataSource contains objects, you should define valueExpr to correctly identify data items. Otherwise, the component uses referential equality to compare objects. For example, when valueExpr is not specified and you assign an object with the same field and values as dataSource to the value property, these two objects are not equal, and the component displays nothing.

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

When dataSource contains objects, you should define valueExpr to correctly identify data items. Otherwise, the component uses referential equality to compare objects, which may result in unexpected behavior.

If you use a store, the valueExpr property should have the same value as the key in the store. Alternatively, you can use this as a valueExpr but the key should be specified. Refer to the following article for more information: Troubleshooting - A Drop-Down Editor Does Not Show Data.

Do not use template as a valueExpr value.

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", "20vw", "80%", "auto", "inherit".

• Function (deprecated since v21.2)
  Refer to the W0017 warning description for information on how you can migrate to viewport units.