Passing information to Ext.data.Model in Extjs

Question

I'm trying to edit an open source program (and learn Extjs meanwhile) and I encountered a problem about models. I don't want to put code here since it is too long but I can provide if necessary.

So I got a a class which extends Ext.form.Panel and model "PartModel" assigned to it. This model has a string field called "partNumber" along with many other fields.

In this panel I want to choose a part number from a combobox from predefined values at database and assign it to "partNumber".

The problem is I want to assign value that is "displayed" in the combobox.(Not one of store fields, I'm using a custom XTemplate for it)

How can I do it?

Edit: Adding combobox code. I thought adding "dataIndex: 'partNumber'" would be sufficient to do job but this code isn't working at all. I can see Part Numbers strings from combobox but when I choose one and hit save button it doesn't save. (There are many other fields working well with that save button maybe I just need to add another button to save part number?)

{
  xtype: 'combobox',
  dataIndex: 'partNumber',
  fieldLabel: "Part Number",
  labelWidth: 150,
  flex: 1,
  store:{
    xtype: 'store',
    autoLoad: true,
    model: 'PartGroupsClasses',
    proxy: getPartGC()},
  queryMode: 'local',
  renderTo:Ext.getBody(),
  tpl:Ext.create('Ext.XTemplate','<tpl for="."><div class="x-boundlist-item">{code}-{descr}-{ccode}-{cdescr}</div></tpl>'),
  displayTpl:Ext.create('Ext.XTemplate','<tpl for=".">{code}{descr}{ccode}{cdescr}</tpl>')
}

Edit2: Figured out save button is basically calling following function.

Ext.override(Ext.data.Model, {
    setDataWithAssociations: function(data) {
        for (var i in data) {
            if (this.fields.containsKey(i)) {
                this.set(i, data[i]);
            }
            if (this.associations.containsKey(i)) {
                var store = this[i]();
                store.add(data[i]);
            }
        }
    }
});

Answer 1

I would do something like this... in your combobox's model, add an extra field that makes use of the convert function to create your displayValue, and then in your combobox, just use that value for your displayValue property.

Model

Ext.define('MyComboModel', {
  extend: 'Ext.data.Model',
  fields: [
    {
      name: 'code',
      type: 'string'
    },
    {
      name: 'desc',
      type: 'string'
    },
    {
      name: 'ccode',
      type: 'string'
    },
    {
      name: 'cdesc',
      type: 'string'
    },
    {
      name: 'displayValue',
      type: 'string',
      convert: function(value, record) {
        return record.get('code') +
          record.get('desc') +
          record.get('ccode') +
          record.get('cdesc');
      }
    }
  ]
});

Combo

    xtype: 'combobox',
    name: 'Field2',
    valueField: 'displayValue',
    displayField: 'displayValue',
    fieldLabel: 'Field2',
    queryMode: 'local',

Full example.