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I am a retired IT Professional (Sales Consultant) who has dabbled in development over the past 20 years.  I have mainly done projects for friends and local businesses and non-profits.  My strengths have always been in database design, and was an active user of all kinds of databases from DB2 to DBase, Informix, Oracle, SQL Server etc..  I was mainly working as an analyst helping design new applications.  This is to explain that I tend to think in database terms when approaching a business problem.  The challenge has always been to build out a suitable front end to control data input and extracts by the user base.  Most of my work in the early 2000's was done in MS Access using VBA to script forms and controls.  I have a warehouse control program used by a local grocery to manage his warehouse which serves 8 stores.  The program has been running since 2006 and has not missed a day.  A couple of years ago, my main user retired and the owner hired three people to replace him.  Of course, they all needed to use the application, which ran on a stand-alone PC.  I wanted to move the program to a MySQL database with a PHP front end.  For the most part, I was able to produce all the reports and charts from the database.  Unfortunately, there is one "killer-app" that Access provided that has been impossible for me to get the client to leave.  This is basically a Master/Child form used to generate purchase orders and invoices.  MS Access has an incredibly integrated way of having a master form with the vendor and a detail form in which the user can quickly (key factor) select product from that vendor and then enter a quantity.  I wound up networking a server and using three PC's to support the business.  It has created many headaches trying to keep the three user's front ends in synch.

I have been able to get close using AJAX and PHP, basically creating an API-like connection to a item table, but the user experience of having the "master" information (Vendor name, address, terms etc.) at the top of the screen and the item details listed below are my personal "holy grail".  I have seen quite a few scripts that come close, but of course many of these are quite a bit simpler than is need for this process.  
Ideally I want the user to be able to select the vendor and have the upper for populate with the data from the vendor table plus today's date and the target ship date..  The user can then make any changes and those changes will be saved in the purchase_order table.  Then the "detail" form will let the user add items from a dropdown (one line at a time).  When the item is selected, the record is updated with the available inventory, the price, weight, suggested retail etc. all of which can be edited and then saved into the purchase_order_detail table.

I am an intermediate when it comes to PHP and JS.  I have been trying hard to embrace the MVC paradigm, and I understand the benefits.  I have been able to successfully build basic CRUD applications over my databases in CI. 
I am looking for any ideas of where I might learn more about building out what I have been calling the "master/detail" form concept using CI.  I am open to any suggestions, and apologize if this is not the proper forum for this question.
Thanks in advance for any helpful suggestions you might have.

Read the CodeIgniter Users Guide and do the tutorial there.

IncludeBeer

has nice tutorials to get you started.


Google Search CodeIgniter 4 Tutorials

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

@emart53 ,

You could also purchase a book (created by the lead developer) https://leanpub.com/codeigniter4foundations . Not only would you be learning about programming with CI4 but you would be supporting the lead developer.

Read the CodeIgniter Users Guide and do the tutorial there.

IncludeBeer

has nice tutorials to get you started.


Google Search CodeIgniter 4 Tutorials

Thanks very much!