In the previous chapter, you have learned how to process a HTML form for searching. In the next chapter, I’ll take a look at inserting data into the database. Before we get there, let’s do a brief side step to better organization of your code, before it gets too cluttered.
By this time, your working folder is probably a mess of experimental half working scripts and you are getting lost in it. If so, it is a good time to put some order in your code.
Do you remember why we have started to use layout templates? Let’s do the same with our PHP code, so far all of the scripts begin with something like:
Let’s move this shared code to a single file and stop copying & pasting it endlessly. We can create
start.php (or whatever name you like), with the above content and only reference it
in the other scripts using
require 'start.php'. This will make other scripts shorter and better arranged.
It also has the nice effect that if you need to change your database password, there will be only one
point of change.
It is important to understand how global variables work in PHP. In PHP a global variable is any variable
not defined inside a function or method.
Therefore most of the variables you have used so far were global.
Global variables are also shared among included files. This means that if we use the variables
$tplVars in the
start.php script and then include (using the
require command) the script in another
PHP script (e.g.
person-list.php), the variables
$tplVars will be initialized.
You can imagine that the
require statement works as if it copies the contents of the include script and
executes it. Hence the
person-list.php starts where the
start.php script ended. This property of global
variables should not be abused. It is practical in what we have done here. You can be sure that the variables
$tplVars will contain what you expect them to contain, and still you don’t have to worry too
much about that.
Also notice that if the database connection fails, the
start.php script will call
exit which terminates the
entire script execution. This means that once our code in
person-list.php is being executed, we are absolutely
sure that the script is successfully connected to the database (otherwise it would exit prematurely).
Currently you have many files in your project:
So let’s bring a few rules into this:
index.php script in the root of your application
With the current files this leads us the following directory structure:
Don’t forget to use proper paths when referencing the files. Specifically:
require 'include/start.php'; and
If you are unsure, there are all the files.
Of course the naming and organization of files is completely up to you. You don’t need to follow the rules I outlined here, but do follow some rules.
Every application starts somewhere. The
index.php file has special behavior in that
it replaces the default directory listing. Every application should have its index
with some useful content.
Sorry, no solution here :) This is completely up to you. If you have no idea what should be on the index page, don’t worry. Something will come to you later.
As your application becomes more complicated, you need to organize the source code files somehow. Better do it before it becomes a complete mess. Find yourself some rules and stick to them – even if you later discover they were not that good, stick to them rather than changing things only in a part of the application.
In this chapter I have shown an example of how the source code can be organized. This allows you to create non-trivial web applications without getting completely lost in the files and source code. Organizing the source code is a very important aspect of software development, though there is no one true solution to it.