In-memory and REST data sources

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Use the in-memory source for browser-owned rows, examples, and tests. Use the REST helpers when application endpoints own remote rows and persistence.

In-memory source

const dataSource = inMemoryGridDataSource({
  schema,
  tree: [
    {
      rowKey: "project-1",
      levelName: "projects",
      columns: { name: "Migration" },
    },
  ],
  levels: {
    projects: {
      sortMode: "client",
      filterMode: "none",
      paginationMode: "none",
    },
  },
});

The in-memory source is not an authorization boundary.

On a tree level, a client filter (filterMode: "client" with compileFilter) keeps each match’s ancestors and, by default, its descendants, and publishes the ancestors that do not match as treeContextRowKeys. The level option treeMatchContext: "ancestors" keeps only the ancestors. A client sort orders the siblings at every depth.

filterTreeSourceNodes() applies the same rule for a custom source:

const { nodes, contextRowKeys, matchCount } = filterTreeSourceNodes(
  allNodes,
  (columns) => String(columns.name).includes("Tax"),
  { parentKeyField: "parent_id", matchContext: "ancestors" },
);

It returns TreeFilterResult: the kept nodes in input order, the context row keys, and the number of rows that match themselves. A parent key that names no row, or a parent loop, ends the walk. TreeMatchContext is "ancestors" | "ancestors-and-descendants".

REST sources

restLevelSource() and restGridDataSource() separate mutable query state from request construction:

rowQuery stores mutable page, page-size, sort, and filter values.
buildRowsRequest adds fixed filters, parent-row constraints, or transport defaults before a fetch runs.
fetchPage returns { nodes, totalCount?, footerRows?, treeContextRowKeys? }. A tree level’s endpoint sets treeContextRowKeys when it returns a filtered tree.
sourceOwnedRowQuery(initial) keeps query state inside a level source.
hostBackedRowQuery(state) adapts application query state to the same source command contract.

Use source-owned query state for embedded levels and child levels without visible controls. Use host-backed query state when toolbar controls, URL state, exports, and row loading must read the same query store.

Remote endpoints remain responsible for authorization, validation, persistence, and conflict handling.

In-memory and REST data sources

In-memory source

REST sources

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