Filtering in React DropDownList component

24 Sep 2021 / 7 minutes to read

The DropDownList has built-in support to filter data items when allowFiltering is enabled. The filter operation starts as soon as you start typing characters in the search box.

To display filtered items in the popup, filter the required data and return it to the DropDownList via updateData method by using the filtering event.

The following sample illustrates how to query the data source and pass the data to the DropDownList through the updateData method in filtering event.

Source

Preview

index.tsx

index.html

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


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

    // maps the appropriate column to fields property
    private fields: object = { text: "Country", value: "Index" };
    // define the filtering data
    private searchData: { [key: string]: Object }[] = [
      { Index: "s1", Country: "Alaska" }, { Index: "s2", Country: "California" },
      { Index: "s3", Country: "Florida" }, { Index: "s4", Country: "Georgia" }
  ];

    // filtering event handler to filter a Country
    public onFiltering(args: FilteringEventArgs) {
        let query = new Query();
        // frame the query based on search string with filter type.
        query = (args.text !== "") ? query.where("Country", "startswith", args.text, true) : query;
        // pass the filter data source, filter query to updateData method.
        args.updateData(this.searchData, query);
    }

    public render() {
        return (
             // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" popupHeight="250px" fields={this.fields} filtering={this.onFiltering = this.onFiltering.bind(this)} allowFiltering={true} dataSource={this.searchData} placeholder="Select a country" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Syncfusion React DropDownList</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for React Components" />
    <meta name="author" content="Syncfusion" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
    <style>
        #loader {
            color: #008cff;
            height: 40px;
            left: 45%;
            position: absolute;
            top: 45%;
            width: 30%;
        }
    </style>
</head>

<body>
    <div id='sample' style="margin: 20px auto 0; width:250px;">
        <div id='loader'>Loading....</div>
    </div>
</body>

</html>

Limit the minimum filter character

When filtering the list items, you can set the limit for character count to raise remote request and fetch filtered data on the DropDownList. This can be done by manual validation within the filter event handler.

In the following example, the remote request does not fetch the search data until the search key contains three characters.

Source

Preview

index.tsx

index.html

import { DataManager, ODataV4Adaptor, Query } from '@syncfusion/ej2-data';
import { SortOrder } from '@syncfusion/ej2-lists';
import { DropDownListComponent, FilteringEventArgs } 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 searchData: DataManager = new DataManager({
    adaptor: new ODataV4Adaptor,
    crossDomain: true,
    url: 'https://services.odata.org/V4/Northwind/Northwind.svc/Customers'
  });
  // maps the appropriate column to fields property
  private fields: object = { text: 'ContactName', value: 'CustomerID' };
  // bind the Query instance to query property
  private query: Query = new Query().select(['ContactName', 'CustomerID']).take(7);
  // sort the resulted items
  private sortOrder: SortOrder = 'Ascending';
  // filtering event handler to filter a customer
  public onFiltering(e: FilteringEventArgs) {
    // load overall data when search key empty.
    if (e.text === '') {
      e.updateData(this.searchData);
    } else {
      // restrict the remote request until search key contains 3 characters.
      if (e.text.length < 3) { return; }
      let query: Query = new Query().select(['ContactName', 'CustomerID']);
      query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
      e.updateData(this.searchData, query);
    }
  }

  public render() {
    return (
      // specifies the tag for render the DropDownList component
      <DropDownListComponent id="ddlelement" allowFiltering={true} popupHeight="250px" filtering={this.onFiltering = this.onFiltering.bind(this)} sortOrder={this.sortOrder} query={this.query} dataSource={this.searchData} fields={this.fields} placeholder="Select a customer" />
    );
  }
}
ReactDOM.render(<App />, document.getElementById('sample'));

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Syncfusion React DropDownList</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for React Components" />
    <meta name="author" content="Syncfusion" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
    <style>
        #loader {
            color: #008cff;
            height: 40px;
            left: 45%;
            position: absolute;
            top: 45%;
            width: 30%;
        }
    </style>
</head>

<body>
    <div id='sample' style="margin: 20px auto 0; width:250px;">
        <div id='loader'>Loading....</div>
    </div>
</body>

</html>

Change the filter type

While filtering, you can change the filter type to contains, startsWith, or endsWith for string type within the filter event handler.

In the following examples, data filtering is done with endsWith type.

Source

Preview

index.tsx

index.html

// import DataManager related classes
import { Query } from '@syncfusion/ej2-data';
import { SortOrder } from '@syncfusion/ej2-lists';
import { DropDownListComponent, FilteringEventArgs } 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 searchData: { [key: string]: Object }[] = [
    { Index: "s1", Country: "Alaska" }, { Index: "s2", Country: "Californiag" },
    { Index: "s3", Country: "Florida" }, { Index: "s4", Country: "Georgia" }
]
// maps the appropriate column to fields property
private fields: object = { value: "Country" };
  // sort the resulted items
  private sortOrder: SortOrder = 'Ascending';
  // filtering event handler to filter a customer
  public onFiltering(e: FilteringEventArgs) {
    // load overall data when search key empty.
    if (e.text === '') {
      e.updateData(this.searchData);
    } else {
      let query: Query = new Query();
      // change the type of filtering
      query = (e.text !== '') ? query.where('Country', 'endsWith', e.text, true) : query;
      e.updateData(this.searchData, query);
    }
  }

  public render() {
    return (
      // specifies the tag for render the DropDownList component
      <DropDownListComponent id="ddlelement" allowFiltering={true} popupHeight="250px" filtering={this.onFiltering = this.onFiltering.bind(this)}  sortOrder={this.sortOrder} dataSource={this.searchData} fields={this.fields} placeholder="Select a customer" />
    );
  }
}
ReactDOM.render(<App />, document.getElementById('sample'));

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Syncfusion React DropDownList</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for React Components" />
    <meta name="author" content="Syncfusion" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
    <style>
        #loader {
            color: #008cff;
            height: 40px;
            left: 45%;
            position: absolute;
            top: 45%;
            width: 30%;
        }
    </style>
</head>

<body>
    <div id='sample' style="margin: 20px auto 0; width:250px;">
        <div id='loader'>Loading....</div>
    </div>
</body>

</html>

Case sensitive filtering

Data items can be filtered either with or without case sensitivity using the DataManager. This can be done by passing the fourth optional parameter of the where clause.

The following example shows how to perform case-sensitive filter.

Source

Preview

index.tsx

index.html

import { Query } from '@syncfusion/ej2-data';
import { SortOrder } from '@syncfusion/ej2-lists';
import { DropDownListComponent, FilteringEventArgs } 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 searchData: { [key: string]: Object }[] = [
      { Index: "s1", Country: "Alaska" }, { Index: "s2", Country: "Californiag" },
      { Index: "s3", Country: "Florida" }, { Index: "s4", Country: "Georgia" }
  ]
  // maps the appropriate column to fields property
  private fields: object = { value: "Country" };
    // sort the resulted items
    private sortOrder: SortOrder = 'Ascending';
    // filtering event handler to filter a customer
    public onFiltering(e: FilteringEventArgs) {
      // load overall data when search key empty.
      if (e.text === '') {
        e.updateData(this.searchData);
      } else {
        let query: Query = new Query();
        // change the type of filtering
        query = (e.text !== '') ? query.where('Country', 'contains', e.text, false) : query;
        e.updateData(this.searchData, query);
      }
    }

    public render() {
        return (
             // specifies the tag for render the DropDownList component
            <DropDownListComponent id="ddlelement" popupHeight="245px" allowFiltering={true} filtering={this.onFiltering = this.onFiltering.bind(this)} sortOrder={this.sortOrder} dataSource={this.searchData} fields={this.fields} placeholder="Select a customer" />
        );
    }
}
ReactDOM.render(<App />, document.getElementById('sample'));

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Syncfusion React DropDownList</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for React Components" />
    <meta name="author" content="Syncfusion" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
    <style>
        #loader {
            color: #008cff;
            height: 40px;
            left: 45%;
            position: absolute;
            top: 45%;
            width: 30%;
        }
    </style>
</head>

<body>
    <div id='sample' style="margin: 20px auto 0; width:250px;">
        <div id='loader'>Loading....</div>
    </div>
</body>

</html>

Diacritics Filtering

DropDownList supports diacritics filtering which will ignore the diacritics and makes it easier to filter the results in international characters lists when the ignoreAccent is enabled.

In the following sample,data with diacritics are bound as dataSource for DropDownList.

Source

Preview

index.tsx

index.html

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<{}, {}> {
    private diacriticsData: string[] = [
    'Aeróbics',
    'Aeróbics en Agua',
    'Aerografía',
    'Aeromodelaje',
    'Águilas',
    'Ajedrez',
    'Ala Delta',
    'Álbumes de Música',
    'Alusivos',
    'Análisis de Escritura a Mano'];

  public render() {
    return (
           <DropDownListComponent id="diacritics" ignoreAccent={true} dataSource={this.diacriticsData} allowFiltering={true} placeholder="Select a value" filterBarPlaceholder="e.g: aero" />
    );
  }
}
ReactDOM.render(<App />, document.getElementById('sample'));

<!DOCTYPE html>
<html lang="en">

<head>
    <title>Syncfusion React DropDownList</title>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta name="description" content="Essential JS 2 for React Components" />
    <meta name="author" content="Syncfusion" />
    <link href="//cdn.syncfusion.com/ej2/ej2-base/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-inputs/styles/material.css" rel="stylesheet" />
    <link href="//cdn.syncfusion.com/ej2/ej2-react-dropdowns/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
    <style>
        #loader {
            color: #008cff;
            height: 40px;
            left: 45%;
            position: absolute;
            top: 45%;
            width: 30%;
        }
    </style>
</head>

<body>
    <div id='sample' style="margin: 20px auto 0; width:250px;">
        <div id='loader'>Loading....</div>
    </div>
</body>

</html>

Filtering in React DropDownList component

Limit the minimum filter character

Change the filter type

Case sensitive filtering

Diacritics Filtering

See Also