DevExtreme Angular - CustomStore Methods

This section describes the methods used to access data associated with the CustomStore.

byKey(key)

Gets a data item with a specific key.

Parameters:
key:

Object

|

String

|

Number

A data item's key value.

Return Value:

Promise<any> (jQuery or native)

A Promise that is resolved after the data item is loaded. It is a native Promise or a jQuery.Promise when you use jQuery.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • singleKeyStore: CustomStore;
  • compositeKeyStore: CustomStore;
  •  
  • constructor() {
  • // The key consists of a single data field
  • this.singleKeyStore = new CustomStore({
  • key: "field1",
  • // ...
  • });
  • // Gets the data item with "field1" being equal to 1
  • this.singleKeyStore.byKey(1).then(
  • (dataItem) => { /* Process the "dataItem" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  •  
  • // The key consists of several data fields
  • this.compositeKeyStore = new CustomStore({
  • key: [ "field1", "field2" ],
  • // ...
  • });
  • // Gets the data item with both "field1" and "field2" being equal to 1
  • this.compositeKeyStore.byKey({
  • field1: 1,
  • field2: 1
  • }).then(
  • (dataItem) => { /* Process the "dataItem" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }

clearRawDataCache()

Deletes data from the cache. Takes effect only if the cacheRawData property is true.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor( ... ) {
  • this.store = new CustomStore({
  • // CustomStore is configured here
  • cacheRawData: true
  • });
  • this.store.clearRawDataCache();
  • };
  • }

insert(values)

Adds a data item to the store.

Parameters:
values:

Object

A data item.

Return Value:

Promise<any> (jQuery or native)

A Promise that is resolved after a data item is added. It is a native Promise or a jQuery.Promise when you use jQuery.

In the following code, dataObj is a data object added to the database and returned from the server. If the server returns nothing or the store works with local data, dataObj contains the data object passed to the insert method.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // CustomStore is configured here
  • });
  • this.store.insert({ id: 1, name: "John Doe" })
  • .then(
  • (dataObj) => { /* Process the data object here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }
NOTE
The data item's key value should be unique, otherwise, the insertion will fail.

key()

Gets the key property (or properties) as specified in the key property.

Return Value: any

The key property's value.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // ...
  • key: "ProductID"
  • });
  • let keyProps = this.store.key(); // returns "ProductID"
  • };
  • }

keyOf(obj)

Gets a data item's key value.

Parameters:
obj:

Object

A data item.

Return Value: any

The data item's key value.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // ...
  • key: "id"
  • });
  • let key = this.store.keyOf({ id: 1, name: "John Doe" }); // returns 1
  • };
  • }

load()

Starts loading data.

Return Value:

Promise<any> (jQuery or native)

A Promise that is resolved after data is loaded. It is a native Promise or a jQuery.Promise when you use jQuery.

load(options)

Starts loading data.

Parameters:
options:

LoadOptions

Data processing settings.

Return Value:

Promise<any> (jQuery or native)

A Promise that is resolved after data is loaded. It is a native Promise or a jQuery.Promise when you use jQuery.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • import DevExpress from "devextreme/bundles/dx.all";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // CustomStore is configured here
  • });
  • let options: DevExpress.data.LoadOptions = {
  • // Data processing settings are specified here
  • };
  • this.store.load(options)
  • .then(
  • (data) => { /* Process "data" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }

off(eventName)

Detaches all event handlers from a single event.

Parameters:
eventName:

String

The event's name.

Return Value:

CustomStore

The object for which this method is called.

See Also

off(eventName, eventHandler)

Detaches a particular event handler from a single event.

Parameters:
eventName:

String

The event's name.

eventHandler:

Function

The event's handler.

Return Value:

CustomStore

The object for which this method is called.

See Also

on(eventName, eventHandler)

Subscribes to an event.

Parameters:
eventName:

String

The event's name.

eventHandler:

Function

The event's handler.

Return Value:

CustomStore

The object for which this method is called.

Use this method to subscribe to one of the events listed in the Events section.

See Also

on(events)

Subscribes to events.

Parameters:
events:

Object

Events with their handlers: { "eventName1": handler1, "eventName2": handler2, ...}

Return Value:

CustomStore

The object for which this method is called.

Use this method to subscribe to several events with one method call. Available events are listed in the Events section.

See Also

push(changes)

Pushes data changes to the store and notifies the DataSource.

Parameters:
changes:

Array<any>

Data changes to be pushed.

There are three possible data change types:

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // CustomStore is configured here
  • });
  • this.store.push([{ type: "insert", data: data }]);
  • this.store.push([{ type: "update", data: data, key: key }]);
  • this.store.push([{ type: "remove", key: key }]);
  • };
  • }

The DataSource does not automatically sort, group, filter, or otherwise shape pushed data. If it should, enable the reshapeOnPush property. We also recommend specifying the pushAggregationTimeout to reduce the number of updates and recalculations.

When data is grouped or paginated, the UI component bound to the DataSource ignores inserted data items until data is reshaped. Disable grouping and paging or enable reshapeOnPush for the inserted data items to appear immediately after they are pushed. The DataGrid and TreeList UI components have individual grouping and paging properties. Use them instead of the corresponding DataSource properties.

IMPORTANT
This method does not modify the remote data source. It is used to push changes from the remote data source to the store without reloading all data.

DataGrid Real-Time Updates Demo DataGrid SignalR Demo Chart SignalR Demo DataGrid Collaborative Editing Demo

See Also

remove(key)

Removes a data item with a specific key from the store.

Parameters:
key:

Object

|

String

|

Number

A data item's key value.

Return Value:

Promise<void> (jQuery or native)

A Promise that is resolved after the data item is removed. It is a native Promise or a jQuery.Promise when you use jQuery.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • singleKeyStore: CustomStore;
  • compositeKeyStore: CustomStore;
  •  
  • constructor() {
  • // The key consists of a single data field
  • this.singleKeyStore = new CustomStore({
  • key: "field1",
  • // ...
  • });
  • // Removes the data item with "field1" being equal to 1
  • this.singleKeyStore.remove(1)
  • .then(
  • (key) => { /* Process the "key" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  •  
  • // The key consists of several data fields
  • this.compositeKeyStore = new CustomStore({
  • key: [ "field1", "field2" ],
  • // ...
  • });
  • // Removes the data item with both "field1" and "field2" being equal to 1
  • this.compositeKeyStore.remove({
  • field1: 1,
  • field2: 1
  • }).then(
  • (key) => { /* Process the "key" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }

totalCount(options)

Gets the total count of items the load() function returns.

Parameters:
obj:

Object

Filtering and grouping properties.

Object structure:
Name Type Description
filter

Object

A filtering expression; described in the Filtering section.

group

Object

A grouping expression; described in the Grouping section.

Return Value:

Promise<Number> (jQuery or native)

A Promise that is resolved after the total item count is obtained. It is a native Promise or a jQuery.Promise when you use jQuery.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • store: CustomStore;
  • constructor() {
  • this.store = new CustomStore({
  • // CustomStore is configured here
  • });
  • this.store.totalCount()
  • .then(
  • (count) => { /* Process the "count" here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }

update(key, values)

Updates a data item with a specific key.

Parameters:
key:

Object

|

String

|

Number

A data item's key value.

values:

Object

An object with new values for the data item.

Return Value:

Promise<any> (jQuery or native)

A Promise that is resolved after the data item is updated. It is a native Promise or a jQuery.Promise when you use jQuery.

In the following code, dataObj is a data object updated in the database and returned from the server. If the server returns nothing or the store works with local data, dataObj contains the data object passed to the update method.

TypeScript
  • import CustomStore from "devextreme/data/custom_store";
  • // ...
  • export class AppComponent {
  • singleKeyStore: CustomStore;
  • compositeKeyStore: CustomStore;
  •  
  • constructor() {
  • // The key consists of a single data field
  • this.singleKeyStore = new CustomStore({
  • key: "field1",
  • // ...
  • });
  • // Updates the data item with "field1" being equal to 1
  • this.singleKeyStore.update(1, { name: "John Smith" })
  • .then(
  • (dataObj) => { /* Process the data object here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  •  
  • // The key consists of several data fields
  • this.compositeKeyStore = new CustomStore({
  • key: [ "field1", "field2" ],
  • // ...
  • });
  • // Updates the data item with both "field1" and "field2" being equal to 1
  • this.compositeKeyStore.update(
  • { field1: 1, field2: 1 },
  • { name: "John Smith" }
  • ).then(
  • (dataObj) => { /* Process the data object here */ },
  • (error) => { /* Handle the "error" here */ }
  • );
  • };
  • }