Hi there i have the following object:

// JobSchedule.php
class JobSchedule extends DataObject {

public static $db = array(
'JobDate'=>'Date',
'Category'=>'Enum("Leak,Sanitary,Blocked drain")',
'Description'=>'Text',
'Status'=>'Enum("Active,Complete,Cancelled")',
'Start'=>'Time',
'End'=>'Time',
);
}

// Calendar.php

public function PlumberResults() {
$jobs = JobSchedule::get()->groupBy('Category');
return $jobs;

}

When i use this i get the following error: [User Error] Uncaught Exception: Object->__call(): the method 'groupby' does not exist on 'DataList'

How do i go about grouping objects?

You now need to wrap your list in a GroupedList. So, return GroupedList::create(JobSchedule::get())->groupBy('Category');

Thanks for the quick reply:

public function PlumberResults() {
$jobs = GroupedList::create(JobSchedule::get()->groupBy('Category'));
return $jobs;
}

Still returns ----- the method 'groupby' does not exist on 'DataList'

That's because you're still calling it on the DataList, not on the GroupedList. groupedBy() is a method on GroupedList().

Optic, As a hint to simon_w's answer you appear to be missing a bracket in your code ;)

Thanks guys...i got it to work now:

public function Grouptest() {
$group = GroupedList::create(JobSchedule::get())
->groupedBy('Category');
return $group;
}

And in my template i called:
<% loop $Grouptest %>
<% loop $Children %>
$Category - $ID - $Type <br>
<% end_loop %>
<% end_loop %>

THE FOLLOWING WORKED AS WELL

public function Grouptest() {
$group = GroupedList::create(JobSchedule::get());
return $group;
}

AND IN TEMPLATE
<% loop $Grouptest.GroupedBy(Category) %>
<% loop $Children %>
$Category - $ID - $Type <br>
<% end_loop %>
<% end_loop %>