有时候我们在用store 的时候，会有需求要求我们出了valuefield和displayfield还需要其他的值(必须保证自己要求的那个值在我们请求的数据里面有返回给我们)
这个时候我们就可以用findRecord()方法
findRecord( String fieldName, String/RegExp value, [Number startIndex], [Boolean anyMatch], [Boolean caseSensitive], [Boolean exactMatch] ) : Ext.data.Model
Finds the first matching Record in this store by a specific field value.
When store is filtered, finds records only within filter.
Parameters
fieldName : String
The name of the Record field to test.
value : String/RegExp
Either a string that the field value should begin with, or a RegExp to test against the field.
startIndex : Number (optional)
The index to start searching at
Defaults to: 0
anyMatch : Boolean (optional)
True to match any part of the string, not just the beginning
Defaults to: false
caseSensitive : Boolean (optional)
True for case sensitive comparison
Defaults to: false
exactMatch : Boolean (optional)
True to force exact match (^ and $ characters added to the regex).
Defaults to: false
例如：
store.findRecord(“valuefield/displayfield(对应的字段)”, value(获取到的值), 0, false, false, true).data.VALUE_ID
则可以查到value对应的value_id的值