Sort by datetime, then group by date - sorting

Question

I want to sort by a datetime value, and group by a date string.
I have found the sortProperty on the grouper:
You can set this configuration if you want the groups to be sorted on something other then the group string returned by the groupFn. This serves the same role as property on a normal Ext.util.Sorter.
So I tried the following, which only sorts the date correctly:
grouper:{
sortProperty: 'StartDate',
property: 'StartDateOnly',
direction: 'ASC'
},
and I tried the following, which only sorts the time correctly:
grouper:{
sortProperty: 'StartDate',
property: 'StartDateOnly',
direction: 'ASC'
},
sorters: [{
property: 'StartDate',
direction: 'ASC'
}]
You can try it here:
https://fiddle.sencha.com/#view/editor&fiddle/2cei
What am I doing wrong here?

Answer 1

The problem is that you make a sort on a string type but you have date by changing the code on your sencha fiddle like this :
Ext.application({
name : 'Fiddle',
launch : function() {
var mdl = Ext.define('', {
extend: 'Ext.data.Model',
fields: [{
/** #field {date} StartDate with format: Y-m-d H:i */
name: 'StartDate',
type: 'date',
dateFormat: 'Y-m-d H:i'
},{
name: 'StartDateOnly',
type: 'date', // <= here before it was 'string'
convert: function(v,rec) {
return Ext.Date.format(rec.get('StartDate'), 'D d.m.Y');
}
}]
});
...
Then you run, you can see that the group of date StartDateOnly is now order by ASC.
After that, you can retrieve this data in date format and convert it into a string. But if you make a sort on a string you will always have the first of February last like now.
The problem is that it does an alphabetical sort on the days of the week.
In order: Fri, Sat, Thu.

Answer 2

Sencha support did not provide a full solution, but helped me a bit on my way. They found how to "fix" the problem at hand and told me to change the data type of the StartDateOnly column to date, but neither did this fix prove universal nor did it make any sense that this fixed the problem at all. But it showed some underlying correlations, which helped me to dig into the problem and find a universal solution.
I would say the issue is a bug in ExtJS, but I am awaiting confirmation from Sencha on this. I have to yet find the exact line where the bug is introduced.
Problem description:
When sortProperty is set on the grouper and at least one sorter is added on the store, the "transform" function of the grouper is set to the "transform" function of the first sorter (otherwise, it is null).
Solution:
You can manually override the transform function on the grouper by adding the correct sort type explicitly to the grouper config:
grouper:{
sortProperty: 'StartDate',
property: 'StartDateOnly',
transform: Ext.data.SortTypes.asDate,
direction: 'ASC'
},