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[MUSIC]

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We've been building our website using
the Drupal web interface so far.

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But there's a lot more you can
do if you can program PHP.

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Drupal is written in PHP, and
with a little programming,

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you can create your own modules to make
Drupal do exactly what you need it to.

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There aer many reasons to learn
how to build your own modules.

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A custom module could
create new content types.

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Custom modules can also implement
behaviors like email notification,

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personal messaging between users, and
displaying content dynamically with Ajax.

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Another common use for
custom modules, is to supplement or

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modify the behavior of
existing contrib modules.

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But if we start simple and learn
the basic mechanics of how to create and

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enable your own module, then you'll
be able to expand these techniques

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to customize Drupal in
whatever ways you need.

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Let's make a simple module that
will greet a user with the message,

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hello my dear friend.

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First, open your project directory and
create a folder for your module in sites,

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all, modules.

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Notice this is the same place
we put our contrib modules.

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This new folder must have the same name
as the module that you're building.

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It should have a meaningful name,
suggesting its purpose.

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In this case,
we're going to call it greeting.

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Now, we're going to open our text editor.

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I'm using Sublime text, but
you can use whatever editor you'd like.

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See the teacher's notes for suggestions.

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Now we're going to create two files and

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save them inside of our
new greeting folder.

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The first one is going to
be called greeting.module,

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and the second one is going
to be called greeting.info.

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The .module file will
contain the core of the code

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defining the behavior of the module.

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The .info file gives Drupal
information about your module,

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such as the module name and description.

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There can be other files
included in a module, but

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the dot module and
dot info files are the only ones required.

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Let's start with the greeting.info file.

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We're going to type name = Greeting,

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with a capital G, and

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description = Display greetings.

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Then we're going to type
package = My First Modules.

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Core = 7.x.

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Finally, we'll say,
files and then opening and

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closing square brackets = greeting.module,
the name of our other file.

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The .info file needs these five things,
name,

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description, package, core, and files.

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Name, description and package are
displayed in the module's administration

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page where you can enable your module.

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Core defines which version of Drupal
the module is compatible with.

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We're using Drupal 7,
so core is set to 7.x.

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The files parameter is an array

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containing the relative paths
to any external files to load.

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Also, while the .module
code is written in PHP,

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we don't want to use
the PHP tags like this.

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Leave it plain.

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Now let's save that file and
work on the greeting.module file.

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The Drupal standard says that we should
start with the opening PHP tag like this,

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but you do not use the closing
tag at the bottom of the file.

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By not closing out the PHP tag,
we eliminate the possibility for

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excessive white space errors,
as well as some validation issues.

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This is one of a number
of coding standards for

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Drupal that you can find
on the drupal.org website.

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See the teacher's notes for
more information.

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After we open our PHP tag,
we declare two functions.

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The first one's job is to
return an array of information,

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and the second one's job
is to return some HTML.

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We start with the function keyword and

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we'll name this function, greeting_menu.

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Give it some parentheses and
the opening and closing curly brackets.

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Then let's go ahead and
declare our second one.

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Function, and
we'll call this one say_hello.

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Parentheses and curly brackets.

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Now, inside of the first one, we're going
to declare a variable called items,

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and we're going to set it
equal to a blank array.

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Then, we're going to insert a key and
value into the items array.

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The key will be, hello_friend, and
it is going to equal another array.

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Put the semicolon at the end and

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then this array will also
consist of key value pairs.

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First we have title,
which we're setting equal to Hello Friend,

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exclamation mark, and then a comma.

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Then we have page callback.

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We're going to set that equal to
the name of our second function,

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say_hello.

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Then, we have the access callback,

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which is equal to TRUE,
and we have the type,

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which is equal to menu_normal_item.

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All in caps.

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Finally, after creating this array,
we want to return it.

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Return items.

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And now we're gonna put our HTML into the
second function and it will say return.

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Let's give it a paragraph tag, and
then the phrase, Hello my dear friend.

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And the closing paragraph tag.

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And don't forget the semicolon.

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Now we can save this, and
go into the Drupal web interface to

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enable our module the same way
that we did with contrib modules.

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Click on Modules in the management menu,

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and then scroll down until you see
your newly added greeting module.

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It will be in a package
labeled my first modules.

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You can also see the description
that you listed in the .info file,

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displayed in the module's row.

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Click the check box to enable it and
then click Save configuration.

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At this point if your browser
gets stuck at a blank page at

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localhost:888/admin/modules/list/confirm,
or

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if it's doing what my page is doing right
now, where it doesn't say that the options

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have been successfully saved, then you
know there's an error in your code.

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Usually a syntax error of some sort.

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Go look at your code and
compare it to the code above.

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Try to fix your error and then reload the
page and try again to enable your module.

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See here?

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I skipped a comma.

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Each of these lines in the array needs
to have a comma at the end of it.

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Let's save and try it now.

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I will reload the modules page, and
I will scroll down to the greeting module,

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click to enable it again, and
now I will click Save configuration.

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And since we have successfully fixed it,
the browser comes back to the module's

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page displaying the message,
the configuration options have been saved.

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Now, if you go to your homepage,
you'll see a new link that says,

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Hello Friend, under the navigation menu.

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If you click it, you'll be taken
to localhost:8888/hello_friend,

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where your greeting appears,
styled using Drupal's current theme.

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Let's take a closer look
at the .module file.

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The .module file is divided
into two PHP functions,

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greeting_menu and say_hello.

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greeting_menu handles input and
say_hello handles output.

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Let's go through each
step in greeting_menu.

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First, the greeting menu function
is declared with no arguments.

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Notice also that the first
word of the function name

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is the same as the name of the module.

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Then we create a new array called items,

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then we create a key value
pair in the items array.

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The key is the string hello friend, and

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the value is another array with
four other key value pairs.

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Then, we return the items array.

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You're probably wondering what
that items array is used for.

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Well, it's key is the URL we
use to access our module.

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We define it to be hello_friend so
that we can go to

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http://localhost:8888/hello_friend and

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then we see our greeting on the screen.

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The URL key makes a menu item for us.

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And there it is.

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The array attached to this
key holds information

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that the page needs to load,
called the attributes of the menu item.

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The attribute named page callback

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stores the name of the function to run
when your browser goes to the URL.

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In this case we run
the function say hello,

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which returns a string of
HTML to display on the page.

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Setting the access call
back attribute to TRUE

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just means that any user has
permission to access this URL.

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There you have it!

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You've completed your first
custom Drupal module.

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You're well on your way.