1. Organize your code with MVC
MIS 3502, Fall 2015
Brad Greenwood, PhD
Department of MIS
Fox School of Business
Temple University
10/22/2015

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What Have We Done
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3. Course Overview We are here. To do: MySQL
Weeks 6 & 7
HTML & CSS
Weeks 1 & 2
PHP
Weeks 3 – 5
PDO
Week 8 & 9
To do:
Organize your code with MVC (week 10)
Work with forms (week 11)
Use cookies and sessions (week 12)

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Objectives
Understand what the MVC pattern is.
Understand how the MVC pattern can be used to develop web applications (what files go where, and why)
Understand how functions can be used to perform database processing.
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5. Why do we need the MVC pattern?
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The MVC pattern
The Controller: Act like a traffic cop… receive user input and decide what to do.
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The MVC pattern
The Model: talk to the database. Enforce rules regarding what is / is not valid data.
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The MVC pattern
The View: specifies what the user can see.
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The MVC pattern
SANITY CHECK! – In which of the above would you expect to see code that uses PDO syntax?
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The MVC pattern
SANITY CHECK! – In which of the above would you expect to see a lot of HTML?
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The MVC pattern
SANITY CHECK! – In which of the above would you expect to see a lot of if / else statements?
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Where do the files go?
Up until now, you have been organizing your code like this.
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Where do the files go?
Now we are going to start using folders to manage our php files.
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Where do the files go?
Collectively, this is all a web site.
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Where do the files go?
This is the home page (or landing page) for the site.
The single main.css file is used consistenly throughout the site.
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Where do the files go?
Inside the site, there are two applications.
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Where do the files go?
These folders contain model and view files that will be used on the entire site.
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Where do the files go?
These folders contain additional supporting files used by both the catalog and manager applications.
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Where do the files go?
The cart folder is not yet in use. (You may ignore this for now.)
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Why are we doing this? There are three reasons:
Avoid repeated code.
This concept is commonly referred to as DRY (Don’t Repeat Yourself)
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What’s in here????
Inside the product_catalog application we have index.php. In this context, index.php is the controller.
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What’s in here????
We also have these views. Views are named here with the convention of entity-underscore-verb.
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SANITY CHECK - If I were to see a view named product_add.php, what sort of operation would that page be used for?
SANITY CHECK – Where would I expect to see the code that connects to the database and adds the product information? The same place (the view) or someplace else?
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26. Getting data out of the database
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Putting data in
Notice that this function doesn’t return a value. It has no return statement. It doesn’t really need one. But, what might be a reasonable use of a returned result in this operation?
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28. What you will see in the controller.
Notice that this code is much lighter (more simple) than what the model is doing. Remember the controller is just directing traffic. It should defer “the hard stuff” like data manipulation to the Model files, and data presentation to the View files.
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29. Setting expectations…
So that’s it, right? Every MVC application is structured exactly like this. Right?
Actually no. There are a lot of variations on the MVC pattern. For instance, some developers will put all the controller code in a folder named “controllers”, and others will have lively debates over where form validation should go. The important thing is to be consistent.
But now you have a whole new vocabulary for developing web applications. This vocabulary will help make every implementation of MVC more sensible.
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We call the process of changing the file structure of a web site or a web application, without changing its appearance or behavior: refactoring.
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