Final Class: TreeDataProviderView

Fields

dataMapping

Optional dataMapping to apply

Since:

• 6.2.0

Methods

addEventListener(eventType: string, listener: EventListener): void

Add a callback function to listen for a specific event type.

Parameters:

Name	Type	Description
eventType	string	The event type to listen for.
listener	EventListener	The callback function that receives the event notification.

containsKeys(parameters : FetchByKeysParameters<K>) : Promise<ContainsKeysResults<K>>

Check if there are rows containing the specified keys. If this method is called on a DataProvider returned from getChildDataProvider(key), the rows will be only those from the children of the key.

Parameters:

Name	Type	Description
parameters	FetchByKeysParameters	contains by key parameters

Since:

• 4.2.0

Returns:

Returns Promise which resolves to ContainsKeysResults.

Type

Promise.<ContainsKeysResults>

Example

Check if keys 1001 and 556 are contained

let containsKeys = [1001, 556];
let value = await dataprovider.containsKeys({keys: containsKeys});
let results = value['results'];
if (results.has(1001)) {
  console.log('Has key 1001');
} else if (results.has(556){
  console.log('Has key 556');
}

dispatchEvent(evt: Event): boolean

Dispatch an event and invoke any registered listeners.

Parameters:

Name	Type	Description
event	Event	The event object to dispatch.

Returns:

Return false if a registered listener has cancelled the event. Return true otherwise.

Type

boolean

fetchByKeys(parameters : FetchByKeysParameters<K>) : Promise<FetchByKeysResults<K, D>>

Fetch rows by keys. If this method is called on a DataProvider returned from getChildDataProvider(key), the rows will be only those from the children of the key.

Parameters:

Name	Type	Description
parameters	FetchByKeysParameters	fetch by key parameters

Since:

• 4.2.0

Returns:

Returns Promise which resolves to FetchByKeysResults.

Type

Promise.<FetchByKeysResults>

Example

Fetch for keys 1001 and 556

let fetchKeys = [1001, 556];
let value = await dataprovider.fetchByKeys({keys: fetchKeys});
// get the data for key 1001
console.log(value.results.get(1001).data);

fetchByOffset(parameters: FetchByOffsetParameters<D>): Promise<FetchByOffsetResults<K, D>>

Fetch rows by offset

A generic implementation of this method is available from FetchByOffsetMixin. It is for convenience and may not provide the most efficient implementation for your data provider. Classes that implement the DataProvider interface are encouraged to provide a more efficient implementation.

Parameters:

Name	Type	Description
parameters	FetchByOffsetParameters	fetch by offset parameters

Since:

• 4.2.0

Returns:

Returns Promise which resolves to FetchByOffsetResults.

Type

Promise.<FetchByOffsetResults>

Example

Fetch by offset 5 rows starting at index 2

let result = await dataprovider.fetchByOffset({size: 5, offset: 2});
let results = result['results'];
let data = results.map(function(value) {
  return value['data'];
});
let keys = results.map(function(value) {
  return value['metadata']['key'];
});

fetchFirst(parameters?: FetchListParameters<D>): AsyncIterable<FetchListResult<K, D>>

Get an AsyncIterable object for iterating the data.

AsyncIterable contains a Symbol.asyncIterator method that returns an AsyncIterator. AsyncIterator contains a “next” method for fetching the next block of data.

The "next" method returns a promise that resolves to an object, which contains a "value" property for the data and a "done" property that is set to true when there is no more data to be fetched. The "done" property should be set to true only if there is no "value" in the result. Note that "done" only reflects whether the iterator is done at the time "next" is called. Future calls to "next" may or may not return more rows for a mutable data source.

Please see the DataProvider documentation for more information on custom implementations.

Parameters:

Name	Type	Argument	Description
params	FetchListParameters	<optional>	fetch parameters

See:

• https://github.com/tc39/proposal-async-iteration for further information on AsyncIterable.

Returns:

AsyncIterable with FetchListResult

Type

AsyncIterable.<FetchListResult>

Example

Get an asyncIterator and then fetch first block of data by executing next() on the iterator. Subsequent blocks can be fetched by executing next() again.

let asyncIterator = dataprovider.fetchFirst(options)[Symbol.asyncIterator]();
let result = await asyncIterator.next();
let value = result.value;
let data = value.data;
let keys = value.metadata.map(function(val) {
  return val.key;
});
// true or false for done
let done = result.done;

getCapability(capabilityName: string): any

Determines whether this DataProvider defines a certain feature.

Parameters:

Name	Type	Description
capabilityName	string	capability name. Defined capability names are: "fetchByKeys", "fetchByOffset", "sort", "fetchCapability" and "filter".

Since:

• 4.2.0

Returns:

capability information or null if undefined

• If capabilityName is "fetchByKeys", returns a FetchByKeysCapability object.
• If capabilityName is "fetchByOffset", returns a FetchByOffsetCapability object.
• If capabilityName is "sort", returns a SortCapability object.
• If capabilityName is "filter", returns a FilterCapability object.
• If capabilityName is "fetchCapability", returns a FetchCapability object.

Type

Object

Example

Check what kind of fetchByKeys is defined.

let capabilityInfo = dataprovider.getCapability('fetchByKeys');
if (capabilityInfo.implementation == 'iteration') {
  // the DataProvider supports iteration for fetchByKeys
  ...

getChildDataProvider(key: K): TreeDataProvider<K, D> | null

Get the data provider for the children of the row identified by key.

Parameters:

Name	Type	Description
key	any	key of the row to get child data provider for.

Since:

• 5.1.0

Returns:

A TreeDataProvider if the row can (but doesn't have to) have children; or null if the row cannot have children. Use the isEmpty method on the returned TreeDataProvider to determine if it currently has children.

Type

TreeDataProvider | null

getTotalSize : {Promise.<number>}

Return the total number of rows in this dataprovider

Returns:

Returns a Promise which resolves to the total number of rows. -1 is unknown row count.

Type

Promise.<number>

Example

Get the total rows

let value = await dataprovider.getTotalSize();
if (value == -1) {
  // we don't know the total row count
} else {
  // the total count
  console.log(value);
}

isEmpty(): 'yes' | 'no' | 'unknown'

Returns a string that indicates if this data provider is empty. Valid values are:

• "yes": this data provider is empty.
• "no": this data provider is not empty.
• "unknown": it is not known if this data provider is empty until a fetch is made.

Since:

• 4.2.0

Returns:

string that indicates if this data provider is empty

Type

"yes" | "no" | "unknown"

Example

Check if empty

let isEmpty = dataprovider.isEmpty();
console.log('DataProvider is empty: ' + isEmpty);

removeEventListener(eventType: string, listener: EventListener): void

Remove a listener previously registered with addEventListener.

Parameters:

Name	Type	Description
eventType	string	The event type that the listener was registered for.
listener	EventListener	The callback function that was registered.

Type Definitions

Options<K, D, Kin, Din>

Properties:

Name	Type	Argument	Description
dataMapping	DataMapping.<K, D, Kin, Din>	<optional>	mapping to apply to the data.