Group By Query in Parse.com Cloud Code

Question

I'm trying to get the results of the following sql command in Parse.com using cloud code.

Select shop, count(1) from Membership group by shop;

Is there a way to do so? or I can only get the number of members from selecting each shop?

var query = new Parse.Query("Membership");
query.equalTo("shop",shop_id);
var promise = query.find().then(function(results){
        var number_of_membership_of_one_shop = results.leng
        return results;
    });

you can require underscore and use _.groupBy() – danh Jan 02 '15 at 04:31 — danh, Jan 02 '15 at 04:31

Wayne Ellery · Accepted Answer · 2015-01-02T05:08:47.810

2

Parse unfortunately doesn't support group by.

You could first select all shops and then use a count query for each shop.

var query = new Parse.Query("Membership");
query.equalTo("shop",shop_id);

var promise = query.count().then(function(count){
    var number_of_membership_of_one_shop = count;
    return number_of_membership_of_one_shop;
});

If this is performing too many requests, you could select all the memberships and then count them on the client, but this will have a limit of 1000 so you may need to adopt some other techniques:

var query = new Parse.Query("Membership");
query.select("shop_id");
query.limit(1000);
var storeCounts = [];

queryObject.find({
    success: function (results) {
        for (var i = 0; i < results.length; i++) {
            var shopId = results[i].get('shop_id');

            if (!storeCounts[shopId]) {
                storeCounts[shopId] = 0;
            }

            storeCounts[shopId]++;
        }
    },
    error: function (error) {
        alert("Error: " + error.code + " " + error.message);
    }
});

edited Jan 02 '15 at 05:08

answered Jan 02 '15 at 03:57

Wayne Ellery

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Hi Wayne, thanks for the reply. I'm actually trying to get an array of {shop, number_of_members} from parse query API. Don't want to query the shop one by one. Is there a group_by function that I'm unaware of? – Ng Zhong Qin Jan 02 '15 at 03:58
Is this what you wanted? – Wayne Ellery Jan 02 '15 at 03:59
I think Parse.com doesn't support Group_by. http://stackoverflow.com/questions/22319841/efficient-way-to-query – Ng Zhong Qin Jan 02 '15 at 04:07
I think I know what you want now. I'll take a look. My answer was not the greatest – Wayne Ellery Jan 02 '15 at 04:08
I updated my answer. You are correct, there is no groupBy. I've provided a couple of options to get the numbers that you are after. – Wayne Ellery Jan 02 '15 at 04:29
2

Note that the query has default 100 and max 1000 results limitation. – eth3lbert Jan 02 '15 at 04:55

Group By Query in Parse.com Cloud Code

1 Answers1