Function distinct

databases/mongo.js:527–640

(appId, collectionName, onKey, query, select, sort, limit, skip)

  },

  distinct(appId, collectionName, onKey, query, select, sort, limit, skip) {
    const deferred = q.defer();

    try {
      if (config.mongoDisconnected) {
        deferred.reject('Database Not Connected');
        return deferred.promise;
      }

      const collection = config.mongoClient.db(appId).collection(mongoUtil.collection.getId(appId, collectionName));

      let include = [];

      if (query.$include) {
        if (query.$include.length > 0) {
          include = include.concat(query.$include);
        }
      }

      // delete $include and $includeList recursively
      query = _sanitizeQuery(query);

      const keys = {};
      const indexForDot = onKey.indexOf('.');

      // if DOT in onKey
      //  keys = { beforeDot: { afterDot : "$beforeDot.afterDot"} }
      // else
      //  keys = { onKey : "$"+onKey }
      if (indexForDot !== -1) {
        // not using computed properties as it may not be available in server's nodejs version
        keys[onKey.slice(0, indexForDot)] = { };
        keys[onKey.slice(0, indexForDot)][onKey.slice(indexForDot + 1)] = `$${onKey}`;
      } else keys[onKey] = `$${onKey}`;

      if (!sort || Object.keys(sort).length === 0) sort = { createdAt: 1 };

      if (!query || Object.keys(query).length === 0) {
        query = {
          _id: {
            $exists: true,
          },
        };
      }

      const pipeline = [];
      pipeline.push({ $match: query });
      pipeline.push({ $sort: sort });

      // push the distinct aggregation.
      pipeline.push({
        $group: {
          _id: keys,
          document: {
            $first: '$$ROOT',
          },
        },
      });