linq.js group by, aggregate multiple fields

Question

I am trying to group my data by 2 properties, and sum two other properties for each group. My code is off just a bit, because I am getting the same sum for both the fields (value and quantity). What am I missing? Thanks!

The code -

var linq = Enumerable.from(data);
        var result = linq
            .groupBy(
                "{ pCo: $.portCo , sName: $.secName }",
                "$.value, $.quantity",
                "{ portCo: $.pCo, security: $.sName, value: $$.sum($.value), quantity: $$.sum($.quantity) }",
                "$.pCo + ' ' + $.secName")
            .toArray();

score 2 · Accepted Answer · edited May 23 '17 at 11:54

2

Ok, after n trials and (n-1) errors, got it to work with the following syntax:

var linq = Enumerable.from(data);
        var result = linq
            .groupBy(
                "{ pCo: $.portCo , sName: $.secName }",
                null,
                "{ portCo: $.pCo, security: $.sName, value: $$.sum('$.value'), quantity: $$.sum('$.quantity') }",
                "$.pCo + ' ' + $.secName")
            .toArray();

The rationale for the null is not clear to me, and i needed '$.x' quotes for the property names in the sum function.

Inspiration for the solution from Jeff's answer here - https://stackoverflow.com/a/15647792/2011729

edited May 23 '17 at 11:54

Community

1
1

answered Apr 13 '16 at 13:49

Montoo

31
9

Passing in `null` when a function is expected will be replaced with the identity function. In this case, you just needed to produce an object that contained a `value` and `quantity` property. Your original wasn't a valid expression. Then as you've figured out, you needed to pass in a selector to the `sum()` function. – Jeff Mercado Apr 13 '16 at 16:29

linq.js group by, aggregate multiple fields

1 Answers1