通过一个属性和求和值组合骨干模型

Question

I have a collection where the models look like the following:

ProfileStat = Backbone.Model.extend({
defaults: {
    sessionID: '',
    uID: '',
    keySig: '',
    tempo: '',
    time: '',
    datetime: ''
},
url: function() {
    return apiUrl('Sessions');
}
});

I would like to loop through all the models in this collection, combine all the models that have the same datetime, and add up all their time values.

To give you some context, we basically have users that are putting in sessions in our site, every session gets recorded with the amount of time they have played, but usually they are putting in around 10 sessions a day. We would like to combine all these sessions for any given day, and output the total time they have played into a graph.

Can anyone help me with a method to combine these models based on the day that the user has played, and add up all the time they have played for that given day? Thank you!

Answer 1

I combined usage of a few different underscore methods to do this. Group by to group by the date, Map for creating objects that look exactly how we want, and reduce to sum the items. Let me know if this all makes sense

 arrayOfProfileStats = [{ defaults: { sessionID: '1', uID: '', keySig: '', tempo: '', time: '00:10:00', datetime: '01/01/2000' } }, { defaults: { sessionID: '2', uID: '', keySig: '', tempo: '', time: '00:10:00', datetime: '01/01/2000' } }, { defaults: { sessionID: '3', uID: '', keySig: '', tempo: '', time: '00:10:00', datetime: '01/02/2000' } } ]; function msToHMS(ms) { // 1- Convert to seconds: var seconds = ms / 1000; // 2- Extract hours: var hours = parseInt(seconds / 3600); // 3,600 seconds in 1 hour seconds = seconds % 3600; // seconds remaining after extracting hours // 3- Extract minutes: var minutes = parseInt(seconds / 60); // 60 seconds in 1 minute // 4- Keep only seconds not extracted to minutes: seconds = seconds % 60; return (hours + ":" + minutes + ":" + seconds); } function toMilliseconds(time) { var a = time.split(':'); // split it at the colons return ((parseInt(a[0]) * 60 * 60 + parseInt(a[1]) * 60 + parseInt(a[2])) * 1000); } var timeForEachDay = function() { var grouped = (_.groupBy(arrayOfProfileStats, function(stat) { return stat.defaults.datetime; })); return _.map(grouped, function(profileDate, key) { // At this point we should have a new object that groups the profileStats by datetime // Now we need to sum the times using reduce() return { [key]: msToHMS(_.reduce(_.map(profileDate, function(date) { return toMilliseconds(date.defaults.time); }), function(total, time) { return total + time; }, 0)) }; }); } console.log(timeForEachDay()); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script> 

Answer 2

I used a couple underscore methods to solve this problem. The first function filters through all the models in the collection to ensure that the models being grabbed are after a certain date. The second function sorts through all those chosen models, and sums up the time played.

filtered = this.filter(function (ProfileStat) {
        //convert the current models datetime to unix
        unixDateTime = Moment(ProfileStat.get("datetime")).valueOf();
        //convert the interval date to unix
        intervalDate = Moment(intervalDate).valueOf();
        //only return the sessions that are ahead of the interval date
        return unixDateTime >= intervalDate;

        //iterate through each model returned from the filtered function and combine all the sessions for any given date
    }).forEach(function(ProfileStat){
        //format the current model date time to MM/DD/YYYY
        ProfileStat.attributes.datetime = Moment(ProfileStat.get('datetime')).format('MM/DD/YYYY');
        //store this datetime in a variable
        var date = ProfileStat.attributes.datetime;
        if (dateArray.indexOf(date) == -1) {
             dateArray.push(date);
             var obj = {datetime: date, timePlayed: ProfileStat.attributes.timePlayed,};
             resultArray.push(obj);
         } 
         else {
             resultArray[dateArray.indexOf(date)].timePlayed += ProfileStat.attributes.timePlayed;
         }
    });