MongoProj Examples

examples.js

// To find counts of days of the week use this 
// getUTCDay returns a Day (0-6) see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date for more
// Examples: getUTCMonth for Months (0-11), getUTCHours (0-23)
db.gmail_data.mapReduce(
        function() {
            var dateDoc;
            for( var i = 0; i < this.payload.headers.length; i++ ) {
                var currDoc = this.payload.headers[i];
                if (currDoc.name === 'Date') {
                    dateDoc = currDoc;
                    break;
                }
            }
            if (!dateDoc) {
                emit(null, 1);
                return;
            }
            var parsedDate = new Date(dateDoc.value);
            emit(parsedDate.getUTCDay(), 1);
        },
        function(key, values) { return Array.sum(values) },
        { out: { inline: 1 } }
);

// Returns the top 10 'FROM' fields, sorted

db.gmail_data.aggregate([
    { $group:
      { count: { $sum: 1 },
        _id: {
          $let: {
            vars: { 'from': {
              $arrayElemAt: [
                { $filter: {
                  input: '$payload.headers', as: 'header', cond: { $eq: [ '$$header.name', 'From' ] } }
                }, 0 ]
            } },
            in: '$$from.value'
          }
        }
      }
    },
    { $sort: { count: -1 } },
    { $limit: 10 }
]);