uui-data-sources

name	uui-data-sources
description	Helps work with UUI DataSources (ArrayDataSource, LazyDataSource, AsyncDataSource) powering PickerInput, DataTable, FiltersPanel, and other data-driven components. Use when implementing or fixing features that load, filter, sort, or display lists of data.

UUI Data Sources

UUI DataSources are the core infrastructure for data-driven components like PickerInput, DataTable, FiltersPanel, and PickerModal. They handle loading, filtering, sorting, selection, and tree hierarchies.

Location

• Package: @epam/uui-core
• Path: uui-core/src/data/processing/
• Types: uui-core/src/types/dataSources.ts

DataSource Types

Type	Use Case	Data Flow
ArrayDataSource	In-memory, synchronous list. Items already loaded.	Pass items array. Filtering/search/sorting done client-side.
LazyDataSource	Server-driven, lazy loading. Large or remote data.	api(request, context) fetches on demand. Supports pagination, search, tree.
AsyncDataSource	Fetches once via API, then caches.	api(options) called once; results cached and reused across views.

Hooks (Recommended Usage)

Use hooks instead of instantiating classes directly — they handle lifecycle and prop updates:

import { useArrayDataSource, useLazyDataSource, useAsyncDataSource } from '@epam/uui-core';

useArrayDataSource

For in-memory data:

const dataSource = useArrayDataSource(
    {
        items: myItems,
        getId: (item) => item.id,
        getParentId: (item) => item.parentId, // optional, for tree
    },
    [myItems]
);

useLazyDataSource

For server-driven lazy loading:

const dataSource = useLazyDataSource<TItem, TId, TFilter>(
    {
        api: (request, context) => {
            // request: { filter, sorting, search, range, ids, cursor }
            // context: { parentId, parent } for tree children
            return myApi.fetchItems(request, context);
        },
        getId: (item) => item.id,
        getParentId: (item) => item.parentId,
    },
    []
);

API must return { items: TItem[], count?: number, from?: number, cursor?: any }.

useAsyncDataSource

Fetches once, then caches. Good for dropdowns with fixed options:

const dataSource = useAsyncDataSource(
    {
        api: (options) => svc.api.demo.countries({}, options).then((r) => r.items),
        getId: (item) => item.id,
    },
    []
);

useView and DataSourceState

Components consume DataSources via useView:

const [dataSourceState, setDataSourceState] = useState<DataSourceState>({});
const view = dataSource.useView(dataSourceState, setDataSourceState);

const rows = view.getVisibleRows();
const listProps = view.getListProps();
view.reload();

DataSourceState (uui-core/src/types/dataSources.ts) includes:

• search — search string
• filter — filter object (passed to LazyDataSource API)
• sorting — sort options
• checked — checked item IDs (multi-select)
• selectedId — single selected item
• folded — tree node fold state
• page, pageSize — pagination
• focusedIndex, scrollTo — list position

SetDataSourceState is (update: (prev) => DataSourceState) => void — functional update pattern.

Key Config Options

• getId(item) — Required. Returns unique ID.
• getParentId(item) — Optional. For tree hierarchy. LazyDataSource uses it to load parent chain.
• complexIds — Set true if IDs are objects/arrays (internally JSON.stringified).
• rowOptions / getRowOptions(item) — Row-level options (selectable, checkable, editable).
• cascadeSelection — true | 'explicit' | 'implicit' for parent-child selection behavior.
• isFoldedByDefault(item, state) — Default fold state for tree nodes.
• selectAll — Enable/disable select-all. Default true.

LazyDataSource API Contract

type LazyDataSourceApi<TItem, TId, TFilter> = (
    request: LazyDataSourceApiRequest<TItem, TId, TFilter>,
    context: LazyDataSourceApiRequestContext<TItem, TId>
) => Promise<LazyDataSourceApiResponse<TItem>>;

• Request: filter, sorting, search, range: { from, count }, ids (for specific IDs), cursor (pagination).
• Context: parentId, parent when loading tree children.
• Response: { items, count?, from?, cursor?, totalCount? }.

Common Patterns

PickerInput with DataSource

const dataSource = useArrayDataSource({ items, getId: (i) => i.id }, [items]);
<PickerInput
    dataSource={ dataSource }
    value={ value }
    onValueChange={ setValue }
    getName={ (item) => item.name }
    entityName="Item"
/>

DataTable with DataSource

const dataSource = useArrayDataSource({ items, getId: (i) => i.id }, [items]);
const [tableState, setTableState] = useState<DataTableState>({});
const view = dataSource.useView(tableState, setTableState);
<DataTable
    getRows={ () => view.getVisibleRows() }
    columns={ columns }
    value={ tableState }
    onValueChange={ setTableState }
/>

Tree with getParentId

const dataSource = useArrayDataSource({
    items,
    getId: (i) => i.id,
    getParentId: (i) => i.parentId,
}, [items]);

LazyDataSource clearCache

When data changes on the server, call dataSource.clearCache() (LazyDataSource only) to force reload.

References

• Data source types: uui-core/src/types/dataSources.ts
• ArrayDataSource: uui-core/src/data/processing/ArrayDataSource.tsx
• LazyDataSource: uui-core/src/data/processing/LazyDataSource.tsx
• AsyncDataSource: uui-core/src/data/processing/AsyncDataSource.tsx
• Hooks: uui-core/src/data/processing/hooks/
• Examples: app/src/docs/_examples/dataSources/, app/src/docs/_examples/pickerInput/, app/src/docs/_examples/tables/