Binding Ext.data.JsonStore to linked comboboxes - extjs

Question

I am new to extJS. I have 2 comboboxes which is binded witha common data store.
Below is the store -
comboStore = new Ext.data.JsonStore({
url: 'Getvalues',
root: 'rows',
autoLoad: true,
fields: ['Type', 'TypeDetails']
});
Here Type is a string and TypeDetails is an array list having field Description. A single Type can have multiple Description.
My requirement is, I have to bind one combobox with Type and when ever I select a Type only Description of curresponding Type should be binded with combobox 2.
I have tried -
xtype: 'combo',
id: 'cmbType',
editable: true,
typeAhead: true,
allowBlank: false,
displayField: 'Type',
valueField: 'Type',
hiddenName: 'Type',
store: comboStore,
mode: 'local',
triggerAction: 'all',
selectOnFocus: true,
emptyText: 'Select Type'
, listeners: {
select: function (cmb, record, index) {
}
}
xtype: 'combo',
id: 'cmbDesc',
editable: true,
typeAhead: true,
allowBlank: false,
displayField: 'Description',
valueField: 'Description',
hiddenName: 'Description',
store: comboStore,
mode: 'local',
triggerAction: 'all',
selectOnFocus: true,
emptyText: 'Select Type first'
What should I do in combo1 select?
I am using extJS 3.4

Answer 1

You should use extraParams property of Proxy definition! Like below:
/**
* Model Definition
*/
Ext.define('comboModel', {
extend: 'Ext.data.Model',
fields: [
{name: 'Type', type: 'int'},
{name: 'TypeDetails', type: 'string'}
]
});
/**
* Model Definition
*/
Ext.define('descModel', {
extend: 'Ext.data.Model',
fields: [
{name: 'Description', type: 'int'},
{name: 'DescDetails', type: 'string'}
]
});
/**
* JsonStore Deifinition
*
* Here we will define a JsonStore which will interact server.
* The returning value type from server should be json!
* Also, do not forget to specify root and idProperty
*/
var comboStore = new Ext.data.JsonStore({
model : 'comboModel', // you should identify of your model
proxy: {
type: 'ajax',
url: '/path/to/your/server/url',
reader: {
type: 'json',
root: 'rows',
idProperty: 'ROOT_ID
}
}
});
var descriptionStore = new Ext.data.JsonStore({
model: 'descModel',
proxy: {
type: 'ajax',
url: '/path/to/your/server/url',
reader: {
type: 'json',
root: 'descriptions',
idProperty: 'DESC_ID'
}
}
});
xtype: 'combobox',
store: 'comboStore',
valueField: 'Type',
displayField: 'TypeDetails',
listeners: {
select: function(val) {
// here is the important part, we are sending the query string
// param by url, like /?desc=122332
descriptionStore.proxy.extraParams = {'desc': val.getValue()}
descriptionStore.load();
}
}
xtype: 'combobox',
store: 'descriptionStore',
valueField: 'Description',
displayField: 'DescDetails',