extract string from a json object - extjs

Question

I have an attribute in the extjs code defined as :
datajson: {
'name' : 'Hello',
....
}
Now I need to set the value of a textfield to the name defined inside this attribute.
I have tried the following but its not working:
Ext.getCmp('name').setValue((this.datajson.xyz.name).toString());
The id of the textfield whose value I am trying to set is 'name'
Here is the full code structure.
Ext.define('Test', {
extend : 'Ext.Container',
alias : 'widget.myapp',
datajson:{
'xyz' : {
...
"name" : 'Hello',
...
}
},
initComponent : function() {
this.appcombo = Ext.create('Ext.form.field.ComboBox', {
store: Ext.create('Ext.data.Store', {
fields: ['text'],
data: [
{text: "a"},
{text: "b"},
{text: "c"}
]
}),
listeners: {
select: function(combo, record, index) {
Ext.getCmp('name').setValue((this.datajson.xyz.name).toString());
}
}
});
...
...
//Here we have a textfield within a Panel whose id is 'name'
So basically I am loading the page and then selecting one value in combo box which serves as the event to load the values in the text-fields with the data which is in datajson.
EDIT: More information added.

Answer 1

The scope within your select function no longer contains datajson. To continue to use this.datajson you can pass the required scope into the function using bind
Ext.application({
name: 'Fiddle',
datajson: {
'name': 'Hello'
},
displayName: function (combo, record, index) {
Ext.getCmp('name').setValue((this.datajson.name));
},
launch: function () {
Ext.create('Ext.form.Panel', {
title: 'Contact Info',
width: 300,
bodyPadding: 10,
renderTo: Ext.getBody(),
items: [{
xtype: 'combo',
store: Ext.create('Ext.data.Store', {
fields: ['text'],
data: [{
text: "a"
}, {
text: "b"
}, {
text: "c"
}]
}),
listeners: {
select: this.displayName.bind(this)
}
}, {
xtype: 'textfield',
id: 'name',
fieldLabel: 'Name'
}]
});
}
});