pairBy does not listen to array object changes

[nsharrok]

I've been using plaid-plot with time-scale, linear-scale and use #with pair-by.

When I update the data array with pushObject() the chart is moved to the left by (map-by 'x' data) but the plot is not updated leaving a gap where the new data should be drawn.

I examined the pair-by helper and saw there was no observer for the data array. I made some alterations as shown and got the chart to update properly.
addon/helpers/pair-by.js

import Ember from 'ember';
import Helper from 'ember-helper';
import observer from 'ember-metal/observer';
const { assert } = Ember;

export default Helper.extend({
    compute(params) {
        assert('pair-by requires at least 2 arguments: key, data', params.length >= 2);
        let data = params.pop();
        this.set('array', data);
        assert('last argument must be an array of objects', Ember.isArray(data));
        let [...keys] = params; 

        return data.map((d) => {
            return keys.reduce((acc, k, index) => {
                acc[index] = d[k];
                return acc;
            }, []);
        });
    },
    contentDidChange: observer('array.[]', function() {
        this.recompute();
    })
});

Thanks for all your efforts.
Noel Sharrock

[ivanvanderbyl]

Hey @nsharrok thanks for the issue, would you mind submitting a PR and I'll merge it in, thanks :)