React DropDownBox Props

View on GitHub

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.

Built-in buttons should also be declared in this array. You can find an example in the following demo:

View Demo

View Demo

See Also

• DropDownBox - Getting Started
• Custom Templates

The DropDownBox works with collections of objects or string, number, or boolean values. The component does not support hierarchical data sources.

Depending on your data source, bind the DropDownBox to data as follows. In each case, also specify the valueExpr and displayExpr properties 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";
      $("#dropDownBoxContainer").dxDropDownBox({
          // ...
          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-drop-down-box ...
      [dataSource]="store">
  </dx-drop-down-box>

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

  Vue

  App.vue

  <template> 
      <DxDropDownBox ...
          :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 { DxDropDownBox } from 'devextreme-vue/drop-down-box';
  
  export default {
      components: {
          DxDropDownBox
      },
      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 DropDownBox from 'devextreme-react/drop-down-box';
  
  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 (
              <DropDownBox ...
                  dataSource={store} />
          );
      }
  }
  export default App;

• Any other data source
  Implement a CustomStore.

Regardless of the data source on the input, the DropDownBox 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.

If the element embedded in the DropDownBox UI component is another DevExtreme UI component, their data sources should be interrelated. Refer to the Synchronize with the Embedded Element article for more information.

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

This function receives values from the data field set in the displayExpr property and should return a string that contains text for the input field. If the displayExpr is not set, the function receives full data objects.

The following code demonstrates how to change separators from commas to semicolons by using the displayValueFormatter function. You can try it if you copy this code to the Multiple Selection demo:

$(function() {
    $("#dropDownBoxContainer").dxDropDownBox({
        displayValueFormatter: function(value) {
            return Array.isArray(value) ? value.join("; ") : value;
        },
        // ...
    });
});

<dx-drop-down-box ...
    [displayValueFormatter]="displayValueFormatter"
>
    <!-- ... -->
</dx-drop-down-box>

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

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
    // ...
    displayValueFormatter(value) {
        return Array.isArray(value) ? value.join("; ") : value;
    }
}

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';

import { DxDropDownBoxModule } from 'devextreme-angular';

@NgModule({
declarations: [
    AppComponent
],
imports: [
    BrowserModule,
    DxDropDownBoxModule
],
providers: [],
bootstrap: [AppComponent]
})
export class AppModule { }

<template>
    <DxDropDownBox ...
        :display-value-formatter="displayValueFormatter"
    >
        <!-- ... -->
    </DxDropDownBox>
</template>

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

import { DxDropDownBox } from 'devextreme-vue/drop-down-box';

export default {
    components: {
        DxDropDownBox
    },
    // ...
    methods: {
        displayValueFormatter: function(value) {
            return Array.isArray(value) ? value.join("; ") : value;
        }
    }    
};
</script>

import React from 'react';

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

import { DropDownBox } from 'devextreme-react/drop-down-box';

class App extends React.Component {
    render() {
        return (
            <DropDownBox ...
                displayValueFormatter={this.displayValueFormatter}
            />
        );
    }

    displayValueFormatter(value) {
        return Array.isArray(value) ? value.join("; ") : value;
    }
}

export default App;

View Demo

See Also

• Custom Templates

See Popup Configuration for properties that you can specify in this object.

In the following code, the fieldTemplate is used to stylize the text field with a custom CSS class:

$(function () {
    $("#dropDownBoxContainer").dxDropDownBox({
        // ...
        fieldTemplate: function (value, fieldElement) {
            const result = $("<div class='custom-item'>");
            result
                .dxTextBox({
                    value: value,
                    readOnly: true
                });
            fieldElement.append(result);
        }
    });
});

.custom-item {
    font-size: 16px;
}

<dx-drop-down-box ...
    fieldTemplate="field">
    <div *dxTemplate="let data of 'field'">
        <div class="custom-item">
            <dx-text-box
                [value]="data"
                [readOnly]="true"
            ></dx-text-box>
        </div>
    </div>
</dx-drop-down-box>

.custom-item {
    font-size: 16px;
}

<template>
    <DxDropDownBox ...
        field-template="field">
        <template #field="{ value }">
            <div class="custom-item">
                <DxTextBox
                    :value="value"
                    :read-only="true"
                />
            </div>
        </template>
    </DxDropDownBox>
</template>

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

import DxDropDownBox from 'devextreme-vue/drop-down-box';
import DxTextBox from 'devextreme-vue/text-box';

export default {
    components: {
        DxDropDownBox,
        DxTextBox,
    },
    data() {
        // ...
    },
    methods: {
        // ...
    }
};
</script>

.custom-item {
    font-size: 16px;
}

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

import { DropDownBox } from 'devextreme-react/drop-down-box';
import { TextBox } from 'devextreme-react/text-box';

const fieldRender = value => {
    return (
        <div class="custom-item">
            <TextBox
                defaultValue={value}
                readOnly={true}
            />
        </div>
    );
}

const App = () => <DropDownBox fieldRender={fieldRender}/>;

export default App;

.custom-item {
    font-size: 16px;
}

See Also

• 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(){
    $("#dropDownBoxContainer").dxDropDownBox({
        // ...
        inputAttr: {
            id: "inputId"
        }
    });
});

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

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

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

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

import DxDropDownBox from 'devextreme-vue/drop-down-box';

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

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

import DropDownBox from 'devextreme-react/drop-down-box';

const inputAttr = { id: 'inputId' };

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

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

@(Html.DevExtreme().DropDownBox() _
    .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(){
    $("#dropDownBoxContainer").dxDropDownBox({
        // ...
        inputAttr: {
            'aria-label': 'your-label',
        },
    });
});

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

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

<script>
import DxDropDownBox from 'devextreme-vue/drop-down-box';

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

import DropDownBox from 'devextreme-react/drop-down-box';

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

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

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

See Also

• validationErrors

The DropDownBox uses other UI components to render items. Use the contentTemplate to embed a UI component such as the List or the TreeView. In this case, items are displayed in accordance with the configuration and functionality of the embedded UI component.

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

dropDownBoxInstance.option('items', newItems);

You can use the dataSource property instead of items. It accepts the DataSource object whose underlying stores include API that allows you to update individual items without reassigning the entire item collection.

See Also

• labelMode
• placeholder

This property can have one of the following values:

labelMode	Description	Illustration
"static"	The label is displayed above the input field.
"floating"	The label is used as a placeholder, but when the editor gets focus, the label moves to the position above the input field.
"hidden"	The label is hidden.

If the number of entered characters reaches the value assigned to this property, the UI component does not allow you to enter any more characters.

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

<dx-drop-down-box ...
    (onInitialized)="saveInstance($event)">
</dx-drop-down-box>

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

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

<script>
import DxDropDownBox from 'devextreme-vue/drop-down-box';

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

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

<script setup>
import DxDropDownBox from 'devextreme-vue/drop-down-box';

let dropDownBoxInstance = null;

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

import DropDownBox from 'devextreme-react/drop-down-box';

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

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

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

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

See Also

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

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

<dx-drop-down-box ...
    (onOptionChanged)="handlePropertyChange($event)"> 
</dx-drop-down-box>

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 { DxDropDownBoxModule } from 'devextreme-angular'; 

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

export class AppModule { }  

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

<script>  
import 'devextreme/dist/css/dx.light.css'; 
import DxDropDownBox from 'devextreme-vue/drop-down-box'; 

export default { 
    components: { 
        DxDropDownBox
    }, 
    // ...
    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 DropDownBox from 'devextreme-react/drop-down-box'; 

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

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

See Also

• showDropDownButton

See Also

• label

When this property is set to true, the following applies:

• The editor's value cannot be changed using the UI.
• Built-in action buttons are invisible.

• Custom action buttons are visible but disabled. If a button should not be disabled, set its disabled property to false:

  jQuery

  index.js

  $(function() {
      $("#dropDownBoxContainer").dxDropDownBox({
          // ...
          buttons: [{
              name: "myCustomButton",
              location: "after",
              options: {
                  onClick: function(e) {
                      // ...
                  },
                  disabled: false
              }
          }]
      });
  });

  Angular

  app.component.html

  app.component.ts

  app.module.ts

  <dx-drop-down-box ... >
      <dxi-button
          name="myCustomButton"
          location="after"
          [options]="myCustomButtonConfig">
      </dxi-button>
  </dx-drop-down-box>

  import { Component } from '@angular/core';
  
  @Component({
      selector: 'app-root',
      templateUrl: './app.component.html',
      styleUrls: ['./app.component.css']
  })
  export class AppComponent {
      myCustomButtonConfig = {
          onClick: (e) => {
              // ...
          },
          disabled: false
      };
  }

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

  Vue

  App.vue

  <template>
      <DxDropDownBox ... >
          <DxDropDownBoxButton
              name="myCustomButton"
              location="after"
              :options="myCustomButtonConfig"
          />
      </DxDropDownBox>
  </template>
  
  <script>
  import 'devextreme/dist/css/dx.light.css';
  
  import DxDropDownBox, {
      DxButton as DxDropDownBoxButton
  } from 'devextreme-vue/drop-down-box';
  
  export default {
      components: {
          DxDropDownBox,
          DxDropDownBoxButton
      },
      data() {
          return {
              myCustomButtonConfig: {
                  onClick: (e) => {
                      // ...
                  },
                  disabled: false
              }
          }
      }
  }
  </script>

  React

  App.js

  import React from 'react';
  
  import 'devextreme/dist/css/dx.light.css';
  
  import DropDownBox, {
      Button as DropDownBoxButton
  } from 'devextreme-react/drop-down-box';
  
  class App extends React.Component {
      myCustomButtonConfig = {
          onClick: (e) => {
              // ...
          },
          disabled: false
      };
      render() {
          return (
              <DropDownBox>
                  <DropDownBoxButton
                      name="myCustomButton"
                      location="after"
                      options={this.myCustomButtonConfig}
                  />
              </DropDownBox>
          );
      }
  }
  export default App;

  You can also hide a custom action button when the UI component becomes read-only. Set the button's visible property to false in the onOptionChanged function. To get the button, use the getButton(name) method:

  jQuery

  index.js

  $(function() {
      $("#dropDownBoxContainer").dxDropDownBox({
          // ...
          buttons: [{
              name: "myCustomButton",
              // ...
          }],
          onOptionChanged: function(e) {
              if(e.name == "readOnly") {
                  const myButton = e.component.getButton("myCustomButton");
                  myButton.option("visible", !e.value); // Hide the button when readOnly: true
              }
          }
      });
  });

  Angular

  app.component.html

  app.component.ts

  app.module.ts

  <dx-drop-down-box ...
      (onOptionChanged)="changeButtonState">
      <dxi-button
          name="myCustomButton"
          ...
      ></dxi-button>
  </dx-drop-down-box>

  import { Component } from '@angular/core';
  
  @Component({
      selector: 'app-root',
      templateUrl: './app.component.html',
      styleUrls: ['./app.component.css']
  })
  export class AppComponent {
      changeButtonState(e) {
          if(e.name == 'readOnly') {
              let myButton = e.component.getButton('myCustomButton');
              myButton.option('visible', !e.value); // Hide the button when readOnly: true
          }
      }
  }

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

  Vue

  App.vue

  <template>
      <DxDropDownBox ...
          @option-changed="changeButtonState">
          <DxDropDownBoxButton
              name="myCustomButton"
              ...
          />
      </DxDropDownBox>
  </template>
  
  <script>
  import 'devextreme/dist/css/dx.light.css';
  
  import DxDropDownBox, {
      DxButton as DxDropDownBoxButton
  } from 'devextreme-vue/drop-down-box';
  
  export default {
      components: {
          DxDropDownBox,
          DxDropDownBoxButton
      },
      data() {
          return {
              // ...
          }
      },
      methods: {
          changeButtonState(e) {
              if(e.name == 'readOnly') {
                  let myButton = e.component.getButton('myCustomButton');
                  myButton.option('visible', !e.value); // Hide the button when readOnly: true
              }
          }
      }
  }
  </script>

  React

  App.js

  import React from 'react';
  
  import 'devextreme/dist/css/dx.light.css';
  
  import DropDownBox, {
      Button as DropDownBoxButton
  } from 'devextreme-react/drop-down-box';
  
  class App extends React.Component {
      changeButtonState(e) {
          if(e.name == 'readOnly') {
              let myButton = e.component.getButton('myCustomButton');
              myButton.option('visible', !e.value); // Hide the button when readOnly: true
          }
      }
      render() {
          return (
              <DropDownBox ...
                  onOptionChanged={this.changeButtonState}>
                  <DropDownBoxButton
                      name="myCustomButton"
                      ...
                  />
              </DropDownBox>
          );
      }
  }
  export default App;

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

The Clear button calls the reset method.

See Also

• dropDownButtonTemplate

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

• 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() {
    $("#dropDownBoxContainer").dxDropDownBox({
        // ...
        validationMessagePosition: 'right'
    }).dxValidator({
        validationRules: [{
            type: 'required',
            message: 'Required',
        }],
    });
});

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

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

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

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

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

};
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 dropDownBox = $("#dropDownBoxContainer").dxDropDownBox({
        // ...
    }).dxDropDownBox("instance");

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

<dx-drop-down-box
    [validationStatus]="validationStatus"
    [validationErrors]="validationErrors">
</dx-drop-down-box>

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

<template>
    <DxDropDownBox ...
        :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 (
        <DropDownBox
            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.