Linq.js : Group By two properties (fields)

Question

I have the following array:

var source = [
            { "DistributorId": 1, "DistributorName": "Distributor 01", "PriceListId": 1, "Year": 2014, "Month": 9 },
            { "DistributorId": 1, "DistributorName": "Distributor 01", "PriceListId": 2, "Year": 2014, "Month": 10 },
            { "DistributorId": 2, "DistributorName": "Distributor 02", "PriceListId": 3, "Year": 2014, "Month": 10 },
            { "DistributorId": 3, "DistributorName": "Distributor 03", "PriceListId": 4, "Year": 2014, "Month": 9 },
            { "DistributorId": 3, "DistributorName": "Distributor 03", "PriceListId": 5, "Year": 2014, "Month": 10 }
        ];

I want to to use linq.js to group these array by two fields "DistributorId" and "DistributorName" to get the following result:

var des =
        [
            {
                "DistributorId": 1,
                "DistributorName": "Distributor 01",
                "PriceLists":
                [
                    { "Year": 2014, "Month": 9 },
                    { "Year": 2014, "Month": 10 }
                ]
            },
            {
                "DistributorId": 2,
                "DistributorName": "Distributor 02",
                "PriceLists":
                [
                    { "Year": 2014, "Month": 10 }
                ]
            },
            {
                "DistributorId": 3,
                "DistributorName": "Distributor 03",
                "PriceLists":
                [
                    { "Year": 2014, "Month": 9 },
                    { "Year": 2014, "Month": 10 }
                ]
            }
        ];

score 2 · Accepted Answer · answered Sep 29 '14 at 16:13

2

The overload of group by that you want looks like this:

// Overload:function(keySelector,elementSelector,resultSelector,compareSelector)

First you'll need the key which is a combination of the distributor id and name. Then collect all years and months that have the same distributor id and name. The result of course and a way to compare the key objects (the properties as strings is a simple way to achieve that).

var query = Enumerable.from(data)
    .groupBy(
        "{ Id: $.DistributorId, Name: $.DistributorName }",
        "{ Year: $.Year, Month: $.Month }",
        "{ DistributorId: $.Id, DistributorName: $.Name, PriceLists: $$.toArray() }",
        "String($.Id) + $.Name"
    )
    .toArray();

Just note that I'm using the linq.js 3.x names: methods using lowerCamelCase. Change to UpperCamelCase for older versions.

answered Sep 29 '14 at 16:13

Jeff Mercado

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It works, thanks - Have you faced any issues while working with linq.js 3.x as it is still beta? – Taraman Sep 30 '14 at 07:50
I can't say that I have. It's all the same for the most part. I'm not really using the new methods added but I have no reason think that they wouldn't work. – Jeff Mercado Sep 30 '14 at 13:53
What if I want to return the count such that my ToArray returns the following array of objects [{ "DistributorId": 1, "DistributorName": "Distributor 01", Total: 2} { "DistributorId": 1, "DistributorName": "Distributor 02", Total: 1} { "DistributorId": 1, "DistributorName": "Distributor 03", Total: 2} ] – nav Jan 28 '15 at 16:10

score 0 · Answer 2 · answered Sep 29 '14 at 08:35

This should do the trick:

var source = [
    { "DistributorId": 1, "DistributorName": "Distributor 01", "PriceListId": 1, "Year": 2014, "Month": 9 },
    { "DistributorId": 1, "DistributorName": "Distributor 01", "PriceListId": 2, "Year": 2014, "Month": 10 },
    { "DistributorId": 2, "DistributorName": "Distributor 02", "PriceListId": 3, "Year": 2014, "Month": 10 },
    { "DistributorId": 3, "DistributorName": "Distributor 03", "PriceListId": 4, "Year": 2014, "Month": 9 },
    { "DistributorId": 3, "DistributorName": "Distributor 03", "PriceListId": 5, "Year": 2014, "Month": 10 }
];

var dest = [];
source.map(function(current){
    var id = current.DistributorId - 1;
    dest[id] = dest[id] || {
        "DistributorId": current.DistributorId,
        "DistributorName": current.DistributorName,
        "PriceLists": []
    };
    dest[id].PriceLists.push({ "Year": current.Year, "Month": current.Month });
})

Linq.js : Group By two properties (fields)

2 Answers2