Data binding in React Drop down list component

2 Feb 202324 minutes to read

The DropDownList loads the data either from local data sources or remote data services using the dataSource property. It supports the data type of array or DataManager.

The DropDownList also supports different kinds of data services such as OData, OData V4, and Web API, and data formats such as XML, JSON, and JSONP with the help of DataManager adaptors.

Fields	Type	Description
text	string	Specifies the display text of each list item.
value	number or string	Specifies the hidden data value mapped to each list item that should contain a unique value.
groupBy	string	Specifies the category under which the list item has to be grouped.
iconCss	string	Specifies the icon class of each list item.

When binding complex data to the DropDownList, fields should be mapped correctly. Otherwise, the selected item remains undefined.

Binding local data

Local data can be represented in two ways as described below.

1. Array of simple data

The DropDownList has support to load array of primitive data such as strings and numbers. Here, both value and text field act the same.

[Class-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
export default class App extends React.Component {
    // define the array of string
    sportsData = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];
    render() {
        return (
        // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={this.sportsData} placeholder="Select a game"/>);
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

export default class App extends React.Component<{}, {}> {

    // define the array of string
    private sportsData: string[] = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];

    public render() {
        return (
              // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" dataSource={this.sportsData} placeholder="Select a game" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

[Functional-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
function App() {
    // define the array of string
    const sportsData = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];
    return (
    // specifies the tag for render the DropDownList component
    <DropDownListComponent id="ddlelement" dataSource={sportsData} placeholder="Select a game"/>);
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

function App() {
    // define the array of string
    const sportsData: string[] = ['Badminton', 'Cricket', 'Football', 'Golf', 'Tennis'];

    return (
    // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={sportsData} placeholder="Select a game" />
    );
}
ReactDOM.render(<App />, document.getElementById('sample'));

2. Array of JSON data

The DropDownList can generate its list items through an array of complex data. For this, the appropriate columns should be mapped to the fields property.

In the following example, Id column and Game column from complex data have been mapped to the value field and text field, respectively.

[Class-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
export default class App extends React.Component {
    // define the JSON of data
    sportsData = [
        { Id: 'game1', Game: 'Badminton' },
        { Id: 'game2', Game: 'Football' },
        { Id: 'game3', Game: 'Tennis' }
    ];
    // maps the appropriate column to fields property
    fields = { text: 'Game', value: 'Id' };
    render() {
        return (
        // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={this.sportsData} fields={this.fields} placeholder="Select a game"/>);
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

export default class App extends React.Component<{}, {}> {

    // define the JSON of data
    private sportsData: { [key: string]: Object }[] = [
        { Id: 'game1', Game: 'Badminton' },
        { Id: 'game2', Game: 'Football' },
        { Id: 'game3', Game: 'Tennis' }
    ];

    // maps the appropriate column to fields property
    private fields: object = { text: 'Game', value: 'Id' };

    public render() {
        return (
             // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" dataSource={this.sportsData} fields={this.fields} placeholder="Select a game" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

[Functional-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
function App() {
    // define the JSON of data
    const sportsData = [
        { Id: 'game1', Game: 'Badminton' },
        { Id: 'game2', Game: 'Football' },
        { Id: 'game3', Game: 'Tennis' }
    ];
    // maps the appropriate column to fields property
    const fields = { text: 'Game', value: 'Id' };
    return (
    // specifies the tag for render the DropDownList component
    <DropDownListComponent id="ddlelement" dataSource={sportsData} fields={fields} placeholder="Select a game"/>);
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

function App() {

    // define the JSON of data
    const sportsData: { [key: string]: Object }[] = [
        { Id: 'game1', Game: 'Badminton' },
        { Id: 'game2', Game: 'Football' },
        { Id: 'game3', Game: 'Tennis' }
    ];

    // maps the appropriate column to fields property
    const fields: object = { text: 'Game', value: 'Id' };

    return (
    // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={sportsData} fields={fields} placeholder="Select a game" />
    );
}
ReactDOM.render(<App />, document.getElementById('sample'));

3. Array of Complex data

The DropDownList can generate its list items through an array of complex data. For this, the appropriate columns should be mapped to the fields property.

In the following example, Code.Id column and Country.Name column from complex data have been mapped to the value field and text field, respectively.

[Class-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
export default class App extends React.Component {
    // define the JSON of data
    countriesData = [
        { Country: { Name: 'Australia' }, Code: { Id: 'AU' } },
        { Country: { Name: 'Bermuda' }, Code: { Id: 'BM' } },
        { Country: { Name: 'Canada' }, Code: { Id: 'CA' } },
        { Country: { Name: 'Cameroon' }, Code: { Id: 'CM' } },
        { Country: { Name: 'Denmark' }, Code: { Id: 'DK' } },
        { Country: { Name: 'France' }, Code: { Id: 'FR' } }
    ];
    // maps the appropriate column to fields property
    fields = { text: 'Country.Name', value: 'Code.Id' };
    render() {
        return (
        // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={this.countriesData} fields={this.fields} placeholder="Select a country"/>);
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

export default class App extends React.Component<{}, {}> {

    // define the JSON of data
    private countriesData: { [key: string]: Object }[] = [
        { Country: { Name: 'Australia' }, Code: { Id: 'AU' }},
        { Country: { Name: 'Bermuda' },Code: { Id: 'BM' }},
        { Country:{ Name: 'Canada'}, Code:{ Id: 'CA'} },
        { Country:{Name: 'Cameroon'}, Code:{ Id: 'CM'} },
        { Country:{Name: 'Denmark'}, Code:{ Id: 'DK' }},
        { Country:{Name: 'France'}, Code: { Id:'FR'} }
    ];

    // maps the appropriate column to fields property
    private fields: object = { text: 'Country.Name', value: 'Code.Id' };

    public render() {
        return (
             // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" dataSource={this.countriesData} fields={this.fields} placeholder="Select a country" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

[Functional-component]

index.jsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
function App() {
    // define the JSON of data
    const countriesData = [
        { Country: { Name: 'Australia' }, Code: { Id: 'AU' } },
        { Country: { Name: 'Bermuda' }, Code: { Id: 'BM' } },
        { Country: { Name: 'Canada' }, Code: { Id: 'CA' } },
        { Country: { Name: 'Cameroon' }, Code: { Id: 'CM' } },
        { Country: { Name: 'Denmark' }, Code: { Id: 'DK' } },
        { Country: { Name: 'France' }, Code: { Id: 'FR' } }
    ];
    // maps the appropriate column to fields property
    const fields = { text: 'Country.Name', value: 'Code.Id' };
    return (
    // specifies the tag for render the DropDownList component
    <DropDownListComponent id="ddlelement" dataSource={countriesData} fields={fields} placeholder="Select a country"/>);
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

function App() {

    // define the JSON of data
    const countriesData: { [key: string]: Object }[] = [
        { Country: { Name: 'Australia' }, Code: { Id: 'AU' }},
        { Country: { Name: 'Bermuda' },Code: { Id: 'BM' }},
        { Country:{ Name: 'Canada'}, Code:{ Id: 'CA'} },
        { Country:{Name: 'Cameroon'}, Code:{ Id: 'CM'} },
        { Country:{Name: 'Denmark'}, Code:{ Id: 'DK' }},
        { Country:{Name: 'France'}, Code: { Id:'FR'} }
    ];

    // maps the appropriate column to fields property
    const fields: object = { text: 'Country.Name', value: 'Code.Id' };

    return (
    // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" dataSource={countriesData} fields={fields} placeholder="Select a country" />
    );
}
ReactDOM.render(<App />, document.getElementById('sample'));

Binding remote data

The DropDownList supports retrieval of data from remote data services with the help of DataManager component. The Query property
is used to fetch data from the database and bind it to the DropDownList.

The following sample displays the first 6 contacts from “Customers” table of the Northwind Data Service.

[Class-component]

index.jsx

// import DataManager related classes
import { DataManager, ODataV4Adaptor, Query } from '@syncfusion/ej2-data';
import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
export default class App extends React.Component {
    // bind the DataManager instance to dataSource property
    customerData = new DataManager({
        adaptor: new ODataV4Adaptor,
        crossDomain: true,
        url: 'https://services.odata.org/V4/Northwind/Northwind.svc/'
    });
    // bind the Query instance to query property
    query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    // maps the appropriate column to fields property
    fields = { text: 'ContactName', value: 'CustomerID' };
    // sort the resulted items
    sortOrder = 'Ascending';
    render() {
        return (
        // specifies the tag for render the DropDownList component
        <DropDownListComponent id="ddlelement" query={this.query} dataSource={this.customerData} fields={this.fields} sortOrder={this.sortOrder} placeholder="Select a customer"/>);
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

// import DataManager related classes
import { DataManager, ODataV4Adaptor, Query } from '@syncfusion/ej2-data';
import { SortOrder } from '@syncfusion/ej2-lists';
import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';


export default class App extends React.Component<{}, {}> {
    // bind the DataManager instance to dataSource property
    private customerData: DataManager = new DataManager({
      adaptor: new ODataV4Adaptor,
      crossDomain: true,
        url: 'https://services.odata.org/V4/Northwind/Northwind.svc/'
    });
    // bind the Query instance to query property
    private query: Query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    // maps the appropriate column to fields property
    private fields: object = { text: 'ContactName', value: 'CustomerID' };
    // sort the resulted items
    private sortOrder: SortOrder = 'Ascending';

    public render() {
        return (
              // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" query={this.query} dataSource={this.customerData}
            fields={this.fields} sortOrder={this.sortOrder} placeholder="Select a customer" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

[Functional-component]

index.jsx

// import DataManager related classes
import { DataManager, ODataV4Adaptor, Query } from '@syncfusion/ej2-data';
import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';
function App() {
    // bind the DataManager instance to dataSource property
    const customerData = new DataManager({
        adaptor: new ODataV4Adaptor,
        crossDomain: true,
        url: 'https://services.odata.org/V4/Northwind/Northwind.svc/'
    });
    // bind the Query instance to query property
    const query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    // maps the appropriate column to fields property
    const fields = { text: 'ContactName', value: 'CustomerID' };
    // sort the resulted items
    const sortOrder = 'Ascending';
    return (
    // specifies the tag for render the DropDownList component
    <DropDownListComponent id="ddlelement" query={query} dataSource={customerData} fields={fields} sortOrder={sortOrder} placeholder="Select a customer"/>);
}
ReactDOM.render(<App />, document.getElementById('sample'));

index.tsx

// import DataManager related classes
import { DataManager, ODataV4Adaptor, Query } from '@syncfusion/ej2-data';
import { SortOrder } from '@syncfusion/ej2-lists';
import { DropDownListComponent } from '@syncfusion/ej2-react-dropdowns';
import * as React from 'react';
import * as ReactDOM from 'react-dom';

function App() {
    // bind the DataManager instance to dataSource property
    const customerData: DataManager = new DataManager({
      adaptor: new ODataV4Adaptor,
      crossDomain: true,
        url: 'https://services.odata.org/V4/Northwind/Northwind.svc/'
    });
    // bind the Query instance to query property
    const query: Query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    // maps the appropriate column to fields property
    const fields: object = { text: 'ContactName', value: 'CustomerID' };
    // sort the resulted items
    const sortOrder: SortOrder = 'Ascending';
    return (
    // specifies the tag for render the DropDownList component
    <DropDownListComponent id="ddlelement" query={query} dataSource={customerData}
        fields={fields} sortOrder={sortOrder} placeholder="Select a customer" />
    );
}
ReactDOM.render(<App />, document.getElementById('sample'));

See Also

• How to load data using template
• How to group the data using header
• How to filter the bound data
• How to get the count of the data when using remote data
• How to achieve cascading
• How to add item in between the options
• How to remove an item
• How to preselect the items in dropdownlist