Function reduceView

lib/index.js:8791–8839

(view, results, options)

  }

  function reduceView(view, results, options) {
    if (options.group_level === 0) {
      delete options.group_level;
    }

    const shouldGroup = options.group || options.group_level;
    const reduceFun = reducer(view.reduceFun);
    const groups = [];
    const lvl = isNaN(options.group_level)
      ? Number.POSITIVE_INFINITY
      : options.group_level;

    for (const result of results) {
      const last = groups[groups.length - 1];
      let groupKey = shouldGroup ? result.key : null;

      // only set group_level for array keys
      if (shouldGroup && Array.isArray(groupKey)) {
        groupKey = groupKey.slice(0, lvl);
      }

      if (last && collate(last.groupKey, groupKey) === 0) {
        last.keys.push([result.key, result.id]);
        last.values.push(result.value);
        continue;
      }
      groups.push({
        keys: [[result.key, result.id]],
        values: [result.value],
        groupKey
      });
    }

    results = [];
    for (const group of groups) {
      const reduceTry = tryReduce(view.sourceDB, reduceFun, group.keys, group.values, false);
      if (reduceTry.error && reduceTry.error instanceof BuiltInError) {
        // CouchDB returns an error if a built-in errors out
        throw reduceTry.error;
      }
      results.push({
        // CouchDB just sets the value to null if a non-built-in errors out
        value: reduceTry.error ? null : reduceTry.output,
        key: group.groupKey
      });
    }
    // no total_rows/offset when reducing
    return { rows: sliceResults(results, options.limit, options.skip) };
  }

  function queryView(view, opts) {
    return sequentialize(getQueue(view), function () {