Final Class: ArrayTreeDataProvider

Oracle® JavaScript Extension Toolkit (JET)
17.0.0
F92240-01

Since:
  • 5.1.0
Module:
  • ojarraytreedataprovider

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Methods

Type Definitions

Description

This class implements TreeDataProvider and is used to represent hierachical data available from an array.

Each array element represents a tree node, which can contain nested child object array for its subtree. Array elements can be in any shape and form, but is usually an object with a "children" property. The name of the "children" property can optionaly be specified with the "childrenAttribute" option.

For nodes that cannot have children, the "children" property should not be set. For nodes that can but don't have children, the "children" property should be set to an empty array.

Data can be passed as a regular array or a Knockout observableArray. If a Knockout observableArray is used, any mutation must be performed with observableArray methods.

ArrayTreeDataProvider subscribes to all changes of Knockout observableArrays including root and any children observableArrays.

The events described below will be dispatched to the ArrayTreeDataProvider with the appropriate event payload.

Filtering is supported and, by default, applied only on leaf nodes. Empty tree nodes are not collapsed. The filtering on leaf nodes only works by combining the passed in filter definition with an OR expression of the "children" property to determine if a node is a tree or leaf.

Events

Consumers can add event listeners to listen for the following event types and respond to data change. Event listeners should be added to the root-level ArrayTreeDataProvider created by the application. The root-level ArrayTreeDataProvider receives events for the entire tree. Child-level ArrayTreeDataProvider returned by getChildDataProvider does not receive events.

mutate

This event is fired when items are added to, removed from, or updated in an observableArray. The event is the observableArray specific.

Event payload is found under event.detail, which implements the DataProviderMutationEventDetail interface.

refresh

This event with no payload is fired when the data has been refreshed and components need to re-fetch the data. In this case, the re-fetch is from the root.

This event with payload 'keys' is fired when updated nodes include any changes in their children. The 'keys' is the set of keys of the nodes with changes in their children, and components need to re-fetch the sub-tree of 'keys'. In this case, the re-fetch should be from each key.

Event payload is found under event.detail, which implements the DataProviderRefreshEventDetail interface.

Example of a tree structured data: 

// initiate a nested observable array
const obData = ko.observableArray([
  {title:"News", id:"news"},
  {title:"Blogs", id:"blogs", "children": ko.observableArray([
    {title:"Today", id:"today"},
    {title:"Yesterday", id:"yesterday"},
    {title:"Archive", id:"archive"}
  ])}
]);

With the data above, the following are actions on an observableArray and events expected.

Action Data Mutation Example Code Expected Events
add a node as a sibling Action is an 'add' on the observableArray containing the node. This action has no impact to the parent node. Add sibling 'Links' to root level obData.push({title: "Links", id: "links"}); 'mutate' with 'add' for node
remove a node Action is a 'remove' on the observableArray containing the node. This action has no impact to the parent node. Remove node 'Links' obData.splice(2,1); 'mutate' with 'remove' for node
add a child to a leaf node The node doesn't have any children (null or undefined), action is an 'update' on the observableArray containting the node which replaces the node with a new node of the same value plus the child under it. Add a child under 'News' const newNode = obData.slice(0,1);
newNode["children"] = new ko.observableArray([{title: "Child1", id: "child1"}]);
obData.splice(0, 1, newNode);		 'mutate' with 'update' for parent
'refresh' with 'keys' for parent
Add a child to a non-leaf node The node already has children (including []) which is an observableArray, action is actually 'add a sibling to a node' where the node is one of the chidren node Add another child under 'News' obData()[0].children.push({title: "Child2", id: "child2"}); 'mutate' with 'add' for child
Update a node without children changes Action is an 'update' on the observableArray containg the node. Update node 'News' to 'OldNews' obData.splice(0,1,{title: "OldNews", id: "news"}); 'mutate' with 'update' for node
Update a node with children changes Action is an 'update' on the observableArray containg the node. Refer to the above 'Add a child to a node' as an example. The children changes could be any changes in the chidren of the node. 'mutate' with 'update' for parent
'refresh' with 'keys' for parent
Reorder or move a node Action is a 'remove' on the original observableArray containging the node, and an 'add a child to a leaf node' if new parent is a leaf node, or 'Add a child to a non-leaf node' if the new parent is a non-leaf node. Move node 'Today' from 'Blogs' to 'News' const moveNode = obData()[1].children.splice(0,1);
obData()[0].children.push(moveNode);		 'mutate' with 'remove' for node
'mutate' with 'add' for node

Example of consumer listening for the events: 

dataProvider.addEventListener("mutate", handleMutate);
dataProvider.addEventListener("refresh", handleRefresh);

const handleMutate = function(event) {
  if (event.detail.remove) {
    const removeDetail = event.detail.remove;
    // Handle removed items
  }
};

const handleRefresh = function(event) {
  const detail=event.detail;
  if (detail && detail.keys) {
    event.detail.keys.forEach ((key) => {
      // refresh children for key
    });
  }
  else {
    // refresh children for root
  }
}
Example of when 'mutate' or 'feresh' event will be fired: 

// initiate a nested observable array
const obData = ko.observableArray([
  {title:"News", id:"news"},
  {title:"Blogs", id:"blogs", "children": ko.observableArray([
    {title:"Today", id:"today"},
    {title:"Yesterday", id:"yesterday"},
    {title:"Archive", id:"archive"}
  ])}
]);

// add a new node to children of 'Blogs' by adding directly to the observableArray obData()[1].children.
// 'mutate' event with add will be fired on observableArray obData()[1].children.
const newNode = {title: 'Future', id: 'future'};
obData()[1].children.push(newNode);

// add a new node to children of 'Blogs' by updating the node 'Blogs' of the observableArray obData with updated children.
// 'mutate' event with update will be fired on observableArray obData.
// 'refresh' event with 'keys' as 'blogs' will be fired since the children of 'blogs' is changed.
const newBlogsNode = {title:"Blogs", id:"blogs", "children": ko.observableArray([
    {title:"Today", id:"today"},
    {title:"Yesterday", id:"yesterday"},
    {title:"Archive", id:"archive"},
    newNode
  ])};
obData.splice(1, 1, newBlogsNode);

Observe that these two ways of mutating data result to the same final data. The observableArray methods apply to different observableArray results to differnt events fired.


Usage

Signature:

final class ArrayTreeDataProvider<K, D> implements TreeDataProvider<K, D>

Generic Parameters
ParameterDescription
KType of Key
DType of Data
Typescript Import Format
//This class is exported directly as module. To import it
import ArrayTreeDataProvider= require("ojs/ojarraytreedataprovider");

For additional information visit:


Final classes in JET

Classes in JET are generally final and do not support subclassing. At the moment, final is not enforced. However, this will likely change in an upcoming JET release.


Constructor

new ArrayTreeDataProvider(data, options)

Parameters:
Name Type Argument Description
data Array | function():Array data supported by the components

This can be either an Array, or a Knockout observableArray.
options ArrayTreeDataProvider.Options.<D> <optional>
 Options for the ArrayTreeDataProvider

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');
}

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
initialMap Map.<any> <optional>
 Optionally 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
initialSet Set.<any> <optional>
 Optionally 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();

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.

In order for JET components to work correctly, DataProvider implementations should ensure that:

  • The iterator accounts for data mutations when returning the next block of data, and that no row is duplicated or skipped. For example, an offset-based implementation may need to adjust the offset from which the next block of data starts if rows have been added or removed in the returned data.
  • JET components may call "next" on the iterator even after the iterator has returned done:true. If new data is available after the last returned row, the iterator is expected to return the new data and set "done" to false. This differs from the AsyncIterator spec for performance reasons.

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

Parameters:
Name Type Argument Description
params FetchListParameters <optional>
 fetch parameters
Since:
  • 4.2.0
See:
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;
});

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

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<D>

Properties:
Name Type Argument Description
childrenAttribute string <optional>
 Optional field name which stores the children of nodes in the data. Dot notation can be used to specify nested attribute. If this is not specified, the default is "children".
implicitSort Array.<SortCriterion.<D>> <optional>
 Optional array of SortCriterion used to specify sort information when the data loaded into the dataprovider is already sorted. This is used for cases where we would like display some indication that the data is already sorted. For example, ojTable will display the column sort indicator for the corresponding column in either ascending or descending order upon initial render. This option is not used for cases where we want the ArrayDataProvider to apply a sort on initial fetch. For those cases, please wrap in a ListDataProviderView and set the sortCriteria property on it.
keyAttributes string | Array<string> <optional>
 Optionally the field name which stores the key in the data. Can be a string denoting a single key attribute or an array of strings for multiple key attributes. Please note that the ids in ArrayDataProvider must always be unique. Please do not introduce duplicate ids, even during temporary mutation operations. @index causes ArrayDataProvider to use index as key and @value will cause ArrayDataProvider to use all attributes as key. @index is the default.

With "@index", the key generation is based on the item index only initially. The key for an item, once assigned, will not change even if the item index changes (e.g. by inserting/removing items from the array). Assigned keys will never be reassigned. If the array is replaced with new items, the new items will be assigned keys that are different from their indices. In general, caller should specify keyAttributes whenever possible and should never assume that the generated keys are the same as the item indices.

This option is ignored if the "keys" option is specified.
keyAttributesScope 'siblings' | 'global' <optional>
 Optional scope of the key values in the fields specified by keyAttributes. Supported values:
  • 'global': the key values are unique within the entire tree.
  • 'siblings': the key values are unique among the siblings of each node.
Default is 'global'.
sortComparators ArrayDataProvider.SortComparators<D> <optional>
 Optional sortComparator to use for sort.
textFilterAttributes string[] <optional>
 Optionally specify which attributes the filter should be applied on when a TextFilter filterCriteria is specified. If this option is not specified then the filter will be applied to all attributes.