src/store/RelayQueryTracker.js

/**
 * Copyright (c) 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule RelayQueryTracker
 * @flow
 */

'use strict';

import type {DataID} from 'RelayInternalTypes';
const RelayNodeInterface = require('RelayNodeInterface');
const RelayQuery = require('RelayQuery');

const flattenRelayQuery = require('flattenRelayQuery');

const TYPE = '__type__';

class RelayQueryTracker {
  _trackedNodesByID: {[key: string]: {
    isMerged: boolean,
    trackedNodes: Array<RelayQuery.Node>,
  }};

  constructor() {
    this._trackedNodesByID = {};
  }

  trackNodeForID(
    node: RelayQuery.Node,
    dataID: DataID
  ): void {
    // Don't track `__type__` fields
    if (node instanceof RelayQuery.Field && node.getSchemaName() === TYPE) {
      return;
    }

    this._trackedNodesByID[dataID] = this._trackedNodesByID[dataID] || {
      trackedNodes: [],
      isMerged: false,
    };
    this._trackedNodesByID[dataID].trackedNodes.push(node);
    this._trackedNodesByID[dataID].isMerged = false;
  }

  /**
   * Get the children that are tracked for the given `dataID`, if any.
   */
  getTrackedChildrenForID(
    dataID: DataID
  ): Array<RelayQuery.Node> {
    const trackedNodesByID = this._trackedNodesByID[dataID];
    if (!trackedNodesByID) {
      return [];
    }
    const {isMerged, trackedNodes} = trackedNodesByID;
    if (!isMerged) {
      const trackedChildren = [];
      trackedNodes.forEach(trackedQuery => {
        trackedChildren.push(...trackedQuery.getChildren());
      });
      trackedNodes.length = 0;
      trackedNodesByID.isMerged = true;
      let containerNode = RelayQuery.Fragment.build(
        'RelayQueryTracker',
        RelayNodeInterface.NODE_TYPE,
        trackedChildren
      );
      containerNode = flattenRelayQuery(containerNode);
      if (containerNode) {
        trackedNodes.push(containerNode);
      }
    }
    const trackedNode = trackedNodes[0];
    if (trackedNode) {
      return trackedNode.getChildren();
    }
    return [];
  }

  /**
   * Removes all nodes that are tracking the given DataID from the
   * query-tracker.
   */
  untrackNodesForID(
    dataID: DataID
  ): void {
    delete this._trackedNodesByID[dataID];
  }
}

module.exports = RelayQueryTracker;