You only take the label for the column defintion in Chart::prepareData(), so you cannot support date string representation for hAxis and therefore no trendlines.
With this patch, you will also respect the type definition from columns, allowing us to format datetime as date string representation, which is necessary for trendlines on datetime based datasets.
You only take the label for the column defintion in Chart::prepareData(), so you cannot support date string representation for hAxis and therefore no trendlines.
With this patch, you will also respect the type definition from columns, allowing us to format datetime as date string representation, which is necessary for trendlines on datetime based datasets.