To use like $leftjoin = new LeftJoin($user_source,$purchase_source,array("id"=>"user_id"));

Ahh... I just noticed that I asked the same question in 2019

https://www.koolreport.com/forum/topics/970

It looks like we do not have it till now. Okeee....

Could you tell me please where I am wrong.

I used to do the following:

     $join1 = new Join($spoiled_tmp, $cons1, array("item_id" => "itemId"));
     $join2 = new Join($join1, $cons2, array("item_id" => "itemId"));
     $join2->pipe($this->dataStore('spoiled'));

It worked but I need Left Join in this case so I added ->pipe($this->dataStore('*****')) to the code where I calculate $spoiled_tmp, $cons1 and $cons2 to get spoiled_tmp, cons1 and cons2 Datastores;

and then I do

$joined= $this->dataStore('spoiled_tmp')
            ->leftJoin($this->dataStore('cons1'), array('item_id' => 'itemId'))
            ->leftJoin($this->dataStore('cons2'), array('item_id' => 'itemId'));
$joined->pipe($this->dataStore('spoiled'));

but I got the empty table where the previous code worked.