Interface: DataProvider

Oracle® JavaScript Extension Toolkit (JET)
8.0.0
F18189-01

Signature:

interface DataProvider<K, D>

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Methods


DataProvider

Version:
  • 8.0.0
Since:
  • 4.2.0
Module:
  • ojdataprovider

Module usage

See JET Module Loading for an overview of module usage within JET.

Typescript Import Format
//To use this interface, import as below.
import {DataProvider} from "ojs/ojdataprovider";
Generic Parameters
ParameterDescription
KType of Key
DType of Data

JET In Typescript

A detailed description of working with JET elements and classes in your typescript project can be found at: JET Typescript Usage.

Description

DataProvider is the basic interface for getting runtime data which JET components that display list of items (such as oj-table and oj-list-view) can use. Please note that these APIs are public and hence the application is also allowed to call methods on it.

JET provides some implementations of this interface, such as oj.ArrayDataProvider.

Applications can also create their own implementations of this interface and use them with JET components that support it. For example, an application can create a DataProvider implementation that fetches data from a REST endpoint.

Implementation class must implement all of the interface methods. It should also fire the events described below when appropriate, so that JET components or other consumers can respond to data change accordingly.

Events

Implementation can fire the following events by creating an instance of the event class and passing the event payload in the constructor.

oj.DataProviderMutationEvent

This event is fired when items have been added or removed from the data.

Event payload should implement the oj.DataProviderMutationEventDetail interface.

Consumers can add an event listener for the "mutate" event type on the DataProvider object.

oj.DataProviderRefreshEvent

This event is fired when the data has been refreshed and components need to re-fetch the data.

This event contains no additional event payload.

Consumers can add an event listener for the "refresh" event type on the DataProvider object.

Example of implementation firing an oj.DataProviderMutationEvent for removed items: 
let removeDetail = {data: removedDataArray,
                    indexes: removedIndexArray,
                    keys: removedKeySet,
                    metadata: removedMetadataArray};
this.dispatchEvent(new oj.DataProviderMutationEvent({remove: removeDetail}));
Example of consumer listening for the "mutate" event type: 
let listener = function(event) {
  if (event.detail.remove) {
    let removeDetail = event.detail.remove;
    // Handle removed items
  }
};
dataProvider.addEventListener("mutate", listener);

Methods

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

Check if there are rows containing the specified keys

A generic implementation of this method is available from oj.FetchByKeysMixin. 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 oj.FetchByKeysParameters contains by key parameters
Since:
  • 4.2.0
Returns:
Returns Promise which resolves to oj.ContainsKeysResults.
Type
Promise.<oj.ContainsKeysResults>
Example

Check if keys 1001 and 556 are contained

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

createOptimizedKeyMap(initialMap?: Map<K, D>): Map<K, D>

Return an empty Map which is optimized to store key value pairs

Optionally provided by certain DataProvider implementations for storing key/value pairs from the DataProvider in a performant fashion. Sometimes components will need to temporarily store a Map of keys provided by the DataProvider, for example, in the case of maintaining a Map of selected keys. Only the DataProvider is aware of the internal structure of keys such as whether they are primitives, Strings, or objects and how to do identity comparisons. Therefore, the DataProvider can optionally provide a Map implementation which can performantly store key/value pairs surfaced by the DataProvider.

Parameters:
Name Type Argument Description
Optionally Map.<any> <optional>
 specify an initial map of key/values for the Map. If not specified, then return an empty Map.
Since:
  • 6.2.0
Returns:
Returns a Map optimized for handling keys from the DataProvider.
Type
Map.<any>
Example

create empty key Map

let keyMap = dataprovider.createOptimizedKeyMap();

createOptimizedKeySet(initialSet?: Set<K>): Set<K>

Return an empty Set which is optimized to store keys

Optionally provided by certain DataProvider implementations for storing keys from the DataProvider in a performant fashion. Sometimes components will need to temporarily store a Set of keys provided by the DataProvider, for example, in the case of maintaining a Set of selected keys. Only the DataProvider is aware of the internal structure of keys such as whether they are primitives, Strings, or objects and how to do identity comparisons. Therefore, the DataProvider can optionally provide a Set implementation which can performantly store keys surfaced by the DataProvider.

Parameters:
Name Type Argument Description
Optionally Set.<any> <optional>
 specify an initial set of keys for the Set. If not specified, then return an empty Set.
Since:
  • 6.2.0
Returns:
Returns a Set optimized for handling keys from the DataProvider.
Type
Set.<any>
Example

create empty key Set

let keySet = dataprovider.createOptimizedKeySet();

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

Fetch rows by keys

A generic implementation of this method is available from oj.FetchByKeysMixin. 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 oj.FetchByKeysParameters fetch by key parameters
Since:
  • 4.2.0
Returns:
Returns Promise which resolves to oj.FetchByKeysResults.
Type
Promise.<oj.FetchByKeysResults>
Example

Fetch for keys 1001 and 556

let fetchKeys = [1001, 556];
dataprovider.fetchByKeys({keys: fetchKeys}).then(function(value) {
  // 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 oj.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 oj.FetchByOffsetParameters fetch by offset parameters
Since:
  • 4.2.0
Returns:
Returns Promise which resolves to oj.FetchByOffsetResults.
Type
Promise.<oj.FetchByOffsetResults>
Example

Fetch by offset 5 rows starting at index 2

dataprovider.fetchByOffset({size: 5, offset: 2}).then(function(value) {
  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 asyncIterator which can be used to fetch a block of data.
Parameters:
Name Type Argument Description
params oj.FetchListParameters <optional>
 fetch parameters
Since:
  • 4.2.0
See:
Returns:
AsyncIterable with oj.FetchListResult
Type
AsyncIterable.<oj.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]();
asyncIterator.next().then(function(result) {
  let value = result.value;
  let data = value.data;
  let keys = value.metadata.map(function(val) {
    return val.key;
});

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", and "filter".
Since:
  • 4.2.0
Returns:
capability information or null if undefined
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
  ...

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

dataprovider.getTotalSize().then(function(value) {
  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);