DevExtreme Angular - DataSource API

The DataSource is an object that provides an API for processing data from an underlying store.

import DataSource from "devextreme/data/data_source"

jQuery

JavaScript

var dataSource = new DevExpress.data.DataSource({
    // ...
    // DataSource is configured here
    // ...
});

Angular

TypeScript

import DataSource from "devextreme/data/data_source";
// ...
export class AppComponent {
    dataSource: DataSource;
    constructor () {
        this.dataSource = new DataSource({
            // ...
            // DataSource is configured here
            // ...
        });
    }
}

Vue

App.vue

<script>
import DataSource from 'devextreme/data/data_source';

const dataSource = new DataSource({
    // ...
    // DataSource is configured here
    // ...
});

export default {
    data() {
        return {
            dataSource
        }
    }
}
</script>

React

App.js

// ...
import DataSource from 'devextreme/data/data_source';

const dataSource = new DataSource({
    // ...
    // DataSource is configured here
    // ...
});

class App extends React.Component {
    // ...
}
export default App;

NOTE

If you create a DataSource instance outside a UI component (as shown above), make sure to dispose of it when it is no longer required. If the instance is created inside a UI component, it is disposed of automatically.
DataSource is not designed to be used in multiple components simultaneously. If you want to share data between multiple widgets, create the store object common for all components. Each component should wrap this store in a separate DataSource.

React

NOTE

If you use DataSource with Next.js, add a use client directive to ensure the instance is created on the client only. DataSource instances do not support React serialization and therefore cannot be created on the server and sent to the client.

Refer to the Data Layer and DataSource Examples articles for more information on working with data in DevExtreme.

NOTE

The DataSource is immutable. You cannot change its configuration at runtime. However, you can use its methods to manipulate it.

Configuration

This section describes properties that configure the DataSource.

Name	Description
customQueryParams	Custom parameters that should be passed to an OData service with the load query. Available only for the ODataStore.
expand	Specifies the navigation properties to be loaded with the OData entity. Available only for the ODataStore.
filter	Specifies data filtering conditions.
group	Specifies data grouping properties.
langParams	Specifies parameters for language-specific sorting and filtering.
map	Specifies an item mapping function.
onChanged	A function that is executed after data is loaded.
onLoadError	A function that is executed when data loading fails.
onLoadingChanged	A function that is executed when the data loading status changes.
pageSize	Specifies the maximum number of data items per page. Applies only if paginate is true.
paginate	Specifies whether the DataSource loads data items by pages or all at once. Defaults to false if group is set; otherwise, true.
postProcess	Specifies a post processing function.
pushAggregationTimeout	Specifies the period (in milliseconds) when changes are aggregated before pushing them to the DataSource.
requireTotalCount	Specifies whether the DataSource requests the total count of data items in the storage.
reshapeOnPush	Specifies whether to reapply sorting, filtering, grouping, and other data processing operations after receiving a push.
searchExpr	Specifies the fields to search.
searchOperation	Specifies the comparison operation used in searching.
searchValue	Specifies the value to which the search expression is compared.
select	Specifies the fields to select from data objects.
sort	Specifies data sorting properties.
store	Configures the store underlying the DataSource.

NOTE

The DataSource allows you to specify CustomStore properties in its configuration object. If you define CustomStore properties as shown in the following code, they override the store.

jQuery

JavaScript

var infiniteList = new DevExpress.data.DataSource({
    load: function (loadOptions) {
        // Loading data objects
    },
    byKey: function (key) {
        // Retrieving a data object by key
    }
});

Angular

TypeScript

import DataSource from "devextreme/data/data_source";
// ...
export class AppComponent {
    infiniteList: DataSource;
    constructor() {
        this.infiniteList = new DataSource({
            load: (loadOptions) => {
                return new Promise((resolve, reject) => {
                    const data = // Loading data objects
                    resolve(data);
                });
            },
            byKey: (key) => {
                return new Promise((resolve, reject) => {
                    const obj = // Retrieving a data object by key
                    resolve(obj);
                });
            }
        });
    }
}

Vue

App.vue

<script>
import DataSource from 'devextreme/data/data_source';

const infiniteList = new DataSource({
    load: (loadOptions) => {
        // Loading data objects
    },
    byKey: (key) => {
        // Retrieving a data object by key
    }
});

export default {
    // ...
    data() {
        return {
            infiniteList
        }
    }
}
</script>

React

App.js

// ...
import DataSource from 'devextreme/data/data_source';

const infiniteList = new DataSource({
    load: (loadOptions) => {
        // Loading data objects
    },
    byKey: (key) => {
        // Retrieving a data object by key
    }
});

class App extends React.Component {
    // ...
}
export default App;

Methods

This section describes methods that control the DataSource.

Name	Description
cancel(operationId)	Cancels the load operation with a specific identifier.
dispose()	Disposes of all the resources allocated to the DataSource instance.
filter()	Gets the filter property's value.
filter(filterExpr)	Sets the filter property's value.
group()	Gets the group property's value.
group(groupExpr)	Sets the group property's value.
isLastPage()	Checks whether the count of items on the current page is less than the pageSize. Takes effect only with enabled paging.
isLoaded()	Checks whether data is loaded in the DataSource.
isLoading()	Checks whether data is being loaded in the DataSource.
items()	Gets an array of data items on the current page.
key()	Gets the value of the underlying store's key property.
load()	Starts loading data.
loadOptions()	Gets an object with current data processing settings.
off(eventName)	Detaches all event handlers from a single event.
off(eventName, eventHandler)	Detaches a particular event handler from a single event.
on(eventName, eventHandler)	Subscribes to an event.
on(events)	Subscribes to events.
pageIndex()	Gets the current page index.
pageIndex(newIndex)	Sets the index of the page that should be loaded on the next load() method call.
pageSize()	Gets the page size.
pageSize(value)	Sets the page size.
paginate()	Gets the paginate property's value.
paginate(value)	Sets the paginate property's value.
reload()	Clears currently loaded DataSource items and calls the load() method.
requireTotalCount()	Gets the requireTotalCount property's value.
requireTotalCount(value)	Sets the requireTotalCount property's value.
searchExpr()	Gets the searchExpr property's value.
searchExpr(expr)	Sets the searchExpr property's value.
searchOperation()	Gets the searchOperation property's value.
searchOperation(op)	Sets the searchOperation property's value.
searchValue()	Gets the searchValue property's value.
searchValue(value)	Sets the searchValue property's value.
select()	Gets the select property's value.
select(expr)	Sets the select property's value.
sort()	Gets the sort property's value.
sort(sortExpr)	Sets the sort property's value.
store()	Gets the instance of the store underlying the DataSource.
totalCount()	Gets the number of data items in the store after the last load() operation without paging. Takes effect only if requireTotalCount is true

Events

This section describes events that the DataSource raises.

Name	Description
changed	Raised after data is loaded.
loadError	Raised when data loading fails.
loadingChanged	Raised when the data loading status is changed.

Name

Description

changed

Raised after data is loaded.

loadError

Raised when data loading fails.

loadingChanged

Raised when the data loading status is changed.