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Code refactoring is the process of restructuring and improving existing code without changing its external behavior. Refactoring allows us to slowly improve our code as we continue to add features. The goals when refactoring are: make the code easier to read, reduce complexity and improve maintainability.
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Refactor vs Rewrite
Modernize Your Legacy PHP Application
Example Code
<?php
function full_catalog_array($limit = null, $offset = 0) {
include("connection.php");
try {
$results = $db->query("SELECT title, category, img FROM Media");
} catch (Exception $e) {
echo "Unable to retrieved results";
exit;
}
$catalog = $results->fetchAll(PDO::FETCH_ASSOC);
return $catalog;
}
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Right now, we have two includes to
work with the catalog, data.php and
0:00
functions.php.
0:05
Our functions file is doing the actual
work of reading the catalog and
0:07
adding the items to our web page.
0:11
So our functions file is really the file
that needs to know about our data.
0:13
Besides, the only thing
our data file is doing now
0:18
is including our connection file.
0:22
So let's change our function file
to include the connection instead,
0:24
then we can clean up the rest of the pages
so they're only including functions.php.
0:28
This, again,
helps us to separate concerns and
0:34
keep duplicated code to a minimum,
making things easier to maintain.
0:37
Let's go into work spaces.
0:42
Let's take a look at our connection file.
0:44
Every time we want to query the database,
0:46
we'll need to instantiate
a PHP data object.
0:48
So we'll leave this block of code that
creates the db variable in this file so
0:52
that it can be included everywhere
we need to run a query.
0:56
The exact query we run will
be different each time, so
1:00
we won't need this second block
of code here in the shared file.
1:04
Instead, we want to move that from our
connection file to our functions file.
1:07
So let's cut the code from here [BLANK
AUDIO] and open our functions.php file.
1:13
In our functions.php file, we're
first going to create a new function.
1:20
We'll name this full_ catalog_array.
1:26
We'll include our connection.php.
1:33
And that gives us the connection to
the database through our PHP data object.
1:40
We're ready to run the query.
1:44
So let's paste in the code to select
all the items from the media table.
1:46
We'll finish off our function and indent.
1:51
We then want to add a return
of our catalog array.
1:55
Our full catalog array function will now
include the connection file to create this
2:05
db object.
2:10
And it then uses that object
to query the database.
2:11
We'll be adding code to query the database
in other places going forward.
2:15
And will be able to include
the connection.php file in those other
2:19
places to connect to the database.
2:23
Without having to duplicate
that block of code.
2:25
The last thing we need to do is change
our files that include our function page.
2:28
So let's open index.php.
2:33
Step one is to remove
the include of data.php.
2:35
Step two, since we no longer
include our data.php file,
2:39
which created a catalog array,
we now need to create that catalog
2:44
array using the call to our new
full_catalog_array function.
2:48
Will get more specific later,
but this will work for now.
2:56
We're going to do this same thing for
the catalog and the details page.
3:00
So let's copy this line.
3:05
We'll open catalog, remove the include
to data and paste this line.
3:09
We'll do the same thing in details
remove data and paste in the line.
3:16
Now, let's go back and preview our site.
3:23
It shouldn't look like anything has
changed until we try to click on an item.
3:28
We then see a bunch of notices and
not really any other details.
3:34
But we now have everything we need in
place to write our second query and
3:38
get the item details page working again.
3:42
Along with adding functionality,
3:45
throughout this project we'll be
utilizing a process called refactoring.
3:47
Code-refactoring is a process
of restructuring and
3:51
improving existing code without
changing its external behavior.
3:55
Refactoring allows us to slowly improve
our code as we continue to add features.
3:59
The goals when refactoring
are make the code easier to read,
4:06
reduce the complexity and
improve maintainability.
4:10
The key to refactoring is to make small,
incremental changes that we can test.
4:14
If something breaks or
doesn't work the way we expect,
4:20
we can always go back to
the original code and try again.
4:23
We keep our application running but
are able to make improvements and
4:27
add features at the same time.
4:31
It's like the boy scouts rule, always
leave things better than you found them.
4:33
Our first three factor may
not seem super useful, but
4:38
it sets us up to be in
a much better place soon.
4:41
Sometimes it may seem hard to
justify the time to refactor when
4:45
you also want to add
functionality to an application.
4:49
Once your code works,
it's tempting to just leave it alone and
4:53
keep programming new features.
4:56
However, experienced programmers
are constantly refactoring
4:59
because they understand the time
it will save in the long run.
5:03
Cleaner code means it's easier to read,
fix bugs, and add features.
5:08
We've already started
to refactor our code.
5:13
Instead of pulling all
the data all the time,
5:15
we'll now be able to ask our functions
to give us just the data we want.
5:18
For example,
pull only the items by JRR Token, or
5:23
more specifically pull
only books by Token.
5:27
It has been said that 80% of a developer's
time is spent reading code and
5:31
only 20% is actually spent writing code.
5:37
Whatever the percentage,
you will spend a lot of time reading code.
5:40
When that code is easier to read,
5:45
it makes programming not only faster but
much more enjoyable.
5:47
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