Problem to solve

JModelList class has a method getListQuery to build the query object use to get list of records from database. However, this method is too generic, so all classes which extends this class must implement this class itself.

The problem is that the code for the getListQuery on all children classes (atleast in Joomla core backend) are almost the same. Look at few of them below:

ContactModelContacts: https://github.com/joomla/joomla-cms/blob/staging/administrator/components/com_contact/models/contacts.php#L148
TagsModelTags: https://github.com/joomla/joomla-cms/blob/staging/administrator/components/com_tags/models/tags.php#L121

we end up writing these repeating code again and again. It wastes time and when we want to change something, we will have to change it in different places.

In this PR, I try to improve the getListQuery method of JModelList, move all these repeating code into the parent class so that children classes won't have to implement it again. At the beginning, I just use this new code in ContactModelContacts and TagsModelTags as the sample. We can work on other classes if this PR is accepted

How to test

This change will only affect to Contacts list and Tags list from backend of the site. So just test and make sure these pages work well

This PR also needs PLT to review code if we want to get this changed get into our system

Possible issue with this PR

This PR use FOFInflector class from FOF, so if FOF is removed from Joomla core in the future, we will need to replace it with similar class. From my experience, we will need to have an string inflector class in Joomla core.