Force Ext to create body element for hidden (collapsed) panel - extjs

Question

I've created a panel bundled with an Ext.Template. This panel is contained in another panel that starts its life collapsed.
id: 'myPanel',
title: 'My Title',
layout: 'border',
collapsible: true,
collapsed: true,
hideCollapseTool:true,
bodyBorder: false,
height: 300,
bodyStyle: 'background:#F9F9F9;',
items: [{
id: 'myDisplayPanel',
bodyStyle: 'background:transparent;',
width: 300,
border: false,
margins: '5 5 5 5',
region: 'west',
tpl: new Ext.Template([
'some template'
])
},
{
id: 'myForm',
xtype: 'form',
bodyStyle: 'background:transparent;',
border: false,
margins: '5 5 5 5',
region: 'center',
[...]
This template-panel is supposed to be updated as the result of a row select in a neighbouring grid. But I get an error the first time I call .update(data); on the myDisplayPanel, as it contains no body element.
myGridSelectionModel: new Ext.grid.RowSelectionModel({
singleselect: true,
listeners: {
rowselect: function(sm,rowIdx,r) {
Ext.getCmp('myDisplayPanel').update(r.data);
Ext.getCmp('myPanel').expand(true);
}
}
}),
The call to myDisplayPanel.update() causes an error when Ext tries to call the template.overwrite function with myDisplayPanel.body as the first param.
function(b,a,c){b=Ext.getDom(b);b.innerHTML=this.applyTemplate(a);
Is it possible somehow to force Ext to generate a body element for this hidden panel before it is beeing shown? I've tried to expand the element prior to updating it, but this has now effect...

Answer 1

I know this thread is 2 months old, so I'm not sure if you ever found a solution. However, I just ran into the same thing and came across your thread while looking for an answer. This is what I ended up doing:
Where you're currently running panel.update(content), try this:
if(panel.rendered) panel.update(content);
else panel.contentToLoad = content;
Set up a listener for the render event to run:
if(this.contentToLoad) panel.update(this.contentToLoad);
That way, if the panel isn't rendered, it will store the content somewhere and the render listener will load whatever is there when the panel IS rendered.

Answer 2

Collapsed panels (and hidden containers in general) by default do not layout their children until they first become visible. You can override this behavior by setting forceLayout: true on the collapsed container. As the name suggests, this will force the container to perform its layout whether it is visible or not. Note that in your case this would be myPanel that would need this configuration, not myDisplayPanel.

Answer 3

You might try Panel's elements config, which from the docs is "A comma-delimited list of panel elements to initialize when the panel is rendered." So e.g.,
elements: ['header','body']
However it already defaults to 'body' only, so it may just be that the panel is truly not rendered yet when you are updating it. Try reversing the order of your calls so that the container is expanded first (should force the child panel to render) then update it.