xidel: add object into json array - arrays

Question

I want extract some information on a website. For this, i use xidel.
I use this command line:
xidel --template-file template.xml --dot-notation=on
and here my template file :
<actions>
<action>
... code before ...
<page url={$url}/>
<pattern>
<div class="row p-r-15 p-l-15 contenu-collec">
{$collection := []}
<t:loop>
{$manga := {}}
<div univers="1">
<div class="post-block collec-titre">
<h2 class="post-title detail-objets">{$manga.title:=.}</h2>
<div>
<input>{$manga.value:=#value}</input>
</div>
</div>
</div>
<!--<call action="test"/>-->
{$collection := $collection.push($manga)}
</t:loop>
</div>
</pattern>
<loop var="t" list="$collection">
<call action="test"/>
</loop>
</action>
<action id="test">
<page url="http://site">
<post name="editions" value="{$t.value}"/>
<post name="action" value="collec_objets_serie"/>
<post name="univers" value="1"/>
<post name="user_id" value="{$userid}"/>
<template>
<!-- <div style="display:block;">{$t.test}</div> -->
<t:loop>
{$t.tome := {}}
<a>{t.tome.url:=#href}</a>
</t:loop>
</template>
</page>
</action>
In the loop i create a object $manga. How to add this object to the $collection array ?
I have tried
{$collection := $collection.push($manga)}
but don't work.