Ext js button in a toolbar - extjs

Question

I would like to ask if there is a possibility to only show a button in the toolbar whenever a if statement is true.
for my case i have a snippet here
{
xtype: 'toolbar',
dock: 'bottom',
items: [
{
xtype: 'button',
text: 'Pay!',
handler: function() {
console.log('haha');
}
}
]
}
a toolbar that has a button
but i only want to show the button pay whenever the grid is not empty(I also have a grid)
how is this possible.
THANKS!

Answer 1

You have to bind to all events that indicate changes of the row count. Most of them are store events:
xtype:'grid',
tbar:[{
xtype:'button',
itemId:'Test'
}],
buttonchange:function() {
this.down('button[itemId=Test]').setVisible(this.getStore().getCount()>0);
},
listeners:{
viewready:function(gridview) {
var grid = gridview.ownerCt;
grid.buttonchange();
store.on({
load: grid.buttonchange(),
add: grid.buttonchange(),
remove: grid.buttonchange(),
clear: grid.buttonchange(),
filterchange: grid.buttonchange(),
scope: grid
});
}
}

Answer 2

Since your grid data handled by a store you have to add store load event listener.
I create working fiddle for you.

Answer 3

If you are using ExtJs5/6+ you might be able to bind the visibility of your button to the store count.
Something like:
{
xtype: 'toolbar',
dock: 'bottom',
items: [
{
xtype: 'button',
text: 'Pay!',
bind: {
hidden: '{!storeCount}'
}
handler: function() {
console.log('haha');
}
}
]
}
And you need to set the storeCount yourself as the property is not accessible directly (see https://www.sencha.com/forum/showthread.php?286770-unable-to-bind-view-to-store-size)
Assuming you have yourStore declared in your ViewModel, in the ViewController you should be able to do
initViewModel: function(viewModel) {
viewModel.bind('{yourStore}', function(store) {
if(store) {
store.on('datachanged', function () {
this.set('storeCount', this.getCount()) // this is the viewModel as I set the scope of the function
});
}
}, viewModel);
}