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Quick start with Migrations plugin

In a previous post I gave an overview of the CakePHP Migrations plugin, what it does and why you should use it in your applications. This article will explain how to use it in a practical way. We are going to bake a simple blog application recipe application and see how migrations are integrated in the development process.

Since we recently moved all our open source projects on http://cakedc.github.com/, this sample application source code is also available there: Sample Migrations Application - Github (it is a CakePHP 1.3 application). Ready?

Bake a new application and add the migrations plugin

First of all, we need to bake a new CakePHP application. Easy enough to do using cake bake, then configure your database (an empty database is sufficient for now) and check that the home page is all green! If you have not set up your environment to use the CakePHP command line yet, take some time to do so... it worth it!

Adding the migrations plugin might also be a straightforward task. You can either download the archive containing the plugin code and unzip it in the "/plugins/migrations" folder of your application, or  add it as a git submodule with the following command:

git submodule add git://github.com/CakeDC/Migrations.git plugins/migrations

Then check that it is correctly installed by executing the following command from your application root:

cake migration help

If you see a list of available commands you can move on next step.

Create initial tables and bake the MVC

We now need something to migrate! Let's create some tables in the database. The application will have Users who can publish Recipes, each one having several Ingredients (of course Ingredients can be used in many Recipes). Here is a SQL dump of this simple database schema:

CREATE TABLE `ingredients` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE `ingredients_recipes` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `ingredient_id` int(11) NOT NULL,
  `recipe_id` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE `recipes` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `name` varchar(100) NOT NULL,
  `content` text NOT NULL,
  `created` datetime NOT NULL,
  `modified` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `password` varchar(255) NOT NULL,
  `created` datetime NOT NULL,
  `modified` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1;

As our goal here is not to focus on the application code itself, baked MVC from these tables might be sufficient... just run the command cake bake all for User, Recipe and Ingredient to bake'em all!

At this point we must have an application with an initial architecture ready to share. To start from here, one will just have to checkout the related commit... but don't you see a problem with this? How will he create the initial database? Maybe we could send him the SQL dump by email, or better commit it with the application! It is where the Migrations plugin comes in.

Generate the initial migration

"Be kind with your coworkers and include the database schema with your code... along with some sample data."

Let's use the migrations shell to generate an agnostic database schema containing our 4 tables, and an initial admin user account. To do so we just need to run the following command:

cake migration generate

After entering a name for the migration and selected the database dump option, we might have a new "/config/migrations" directory containing two files:

  • map.php representing the different migrations order,
  • name_of_the_migration.php a migration file containing all the necessary information to create your actual database. In the sample application it is named: "001_added_users_recipes_and_ingredients_tables.php". You might have noticed that we added a 001 prefix to the migration name to make it easier to see migrations order, it is a good practice.

We can now open the generated migration file (/config/migrations/001_added_users_recipes_and_ingredients_tables.php) and take a look at it. If you need more information and understand all available migration directives, you can read the plugin documentation.

For now we are just going to focus on the empty "after()" callback. This callback is triggered once the migration has been executed, and allow you to do whatever you want, given the direction of the migration: applied (up) or reverted (down). We are going to use this callback to create an initial admin User. Here is the code of the callback (as you are a CakePHP developer you might understand it quite easily):

function after($direction) {
	if ($direction === 'up') {
		if (!class_exists('Security')) {
			App::import('Core', 'Security');
		}

		$User = $this->generateModel('User');
		$user = array(
			'User' => array(
				'name' => 'admin',
				'password' => Security::hash('unsecurepassword', null, true)));
		$User->save($user);
	}
	return true;
}

Notice the use of the generateModel() method provided by the Migrations plugin. It is a shorthand allowing you to cleanly load a model in the callback to insert new data or update the existing. We could explain the reason of it more deeply but it is not the goal of this article, so just keep in mind that it is the best way to load a Model from callbacks!

Here we are! We can now share the application with anyone. After checked out the application, one will just have to run cake migration all to turn an empty database to a database containing all the needed tables, and an initial admin user to start using the application.

Categorize the recipes!

As the application evolves, we need to sort recipes by categories. This change involves two changes in the current database schema: a new categories table must be created, and a category_id field added to the recipes table.

Note: If you later want to use the migrations diff feature to generate a migration containing a diff between your previous database schema and the current one, you have to generate a Cake Schema of your database at this point. Simply run cake schema generate.

We can now update the recipes table and create a new categories table. Here is a simple SQL script:

CREATE TABLE `categories` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1;
ALTER TABLE `recipes` ADD `category_id` INT NOT NULL

Bake the MVC for categories and update recipes view pages to display the category so the application reflect these database changes. Before sharing these code changes, we need to generate a second migration describing the above SQL snippet in an agnostic way... and creating initial categories!

Nothing different than what we did previously: run cake migration generate, give a name to the migration, and choose between generating a diff from the schema.php file (if one was generated), generating a dump of the database (we will remove unnecessary instructions later) or generating an empty migration file. Once generated, it is always important to check the generated directives for the migration and fix them if needed. The migration must look like this:

var $migration = array(
	'up' => array(
		'create_table' => array(
			'categories' => array(
				'id' => array('type' => 'integer', 'null' => false, 'default' => NULL, 'key' => 'primary'),
				'name' => array('type' => 'string', 'null' => false, 'default' => NULL, 'length' => 100),
				'indexes' => array(
					'PRIMARY' => array('column' => 'id', 'unique' => 1),
				),
				'tableParameters' => array('charset' => 'latin1', 'collate' => 'latin1_swedish_ci', 'engine' => 'MyISAM'),
			),
		),
		'create_field' => array(
			'recipes' => array(
				'category_id' => array('type' => 'integer', 'null' => false, 'default' => NULL)
			),
		),
	),
	'down' => array(
		'drop_table' => array(
			'categories'
		),
		'drop_field' => array(
			'recipes' => array(
				'category_id'
			),
		),
	),
);

If you understood what we did in the first migration callback to add an initial user you might be able to implement this one. We would like to add initial categories: Starters, Main Dish and Desserts.

For lazy people, the code is here:

function after($direction) {
	if ($direction === 'up') {
		$Category = $this->generateModel('Category');
		$categories = array(
			array('name' => 'Starters'),
			array('name' => 'Main Dish'),
			array('name' => 'Desserts'));
		$Category->saveAll($categories);
	}
	return true;
}

Here we are again! The changes are ready to commit, and the commit will contains both code and database changes. One could update the database after checking out this commit by running: cake migration all.

The end

I hope this very simple use case and the code we built will help you to start using Migrations. As you could see it is very simple to use and will make your life much more easier: you would not have to worry anymore about the state of your database schema.

The source code of this tutorial is available on Github. If you found any bug or have any suggestion about the Migrations plugin, please create a ticket on Github. Comment this article if you have any question, and do not hesitate to share it if you found it useful!

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CakePHP Upgrade to 4 - Piece by Piece

Let's imagine you have a huge application in CakePHP 2.x (or 1.x) and you're planning to upgrade to the latest CakePHP 4.x. After doing some estimations, you realize the upgrade process is out of your scope, because you don't have the budget or developer availability to do it in 1 shot. At this point, some companies would abort the upgrade and keep working on 2.x for "some more time" until "this last release is delivered" or until "budget is available next fall", digging deeper and deeper into the rabbit hole…   There's an alternative you could follow if this is your case: proceed with the upgrade of a smaller portion of your application and let the 2 versions coexist for some time.   Warning: This is NOT for every project or company. Please carefully think about this decision as it has overhead you'll need to handle.   So, if your application has a portion that could be extracted, with a small set of dependencies from other areas of your application, or if you are creating a new feature with a limited set of dependencies with the rest of your application, this approach would be good for you.   In order to allow both applications to coexist, we are going to keep the CakePHP 1.x application as the main one, and use CakePHP 4.x as a subfolder inside of the first one. It's important to note that in order to share sessions between both applications you'll need to use a storage you can actually share, like database or cache based sessions (redis, etc). Then, you can use a configuration like this one (see below) to add a new upstream to handle your new application. Note: the upstream could be located in another server of your network, using a different PHP version etc.   We've used nginx as an example, but you can use the same approach in other web servers like Apache.   In our example we're going to use all paths starting with /api  to be managed by our new CakePHP 4.x application. upstream cake4 {      # Note this could be any server/port in your network where the cake4 application is installed          server 127.0.0.1:9090; }   # This is our CakePHP 2.x server server {     server_name example.com;       root   /var/virtual/example.com/app/webroot;     index index.php;       # All requests /api are forwarded to our CakePHP 4.x application location /api {         proxy_pass http://cake4;             proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;         proxy_set_header Host $host;             proxy_http_version 1.1;         proxy_set_header Upgrade $http_upgrade;             proxy_set_header Connection "Upgrade";     }       location / {             try_files $uri $uri/ /index.php?$args;     }       location ~ \.php$ {           try_files $uri =404;           include fastcgi_params;                fastcgi_pass unix:/run/php/php7.4-fpm.sock;           fastcgi_index index.php;             fastcgi_intercept_errors on;         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;     } }   # This is our CakePHP 4.x server server {     listen 9090;     server_name example.com;       root   /var/virtual/cake4-example.com/webroot;     index index.php;       location / {         try_files $uri $uri/ /index.php?$args;     }       location ~ \.php$ {         try_files $uri =404;             include fastcgi_params;         fastcgi_pass unix:/run/php/php7.4-fpm.sock;             fastcgi_index index.php;         fastcgi_intercept_errors on;             fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;     } }   As you can see, we have 3 blocks defined in our configuration file:

  • upstream cake4 {...} to forward requests to the CakePHP 4.x application
  • server {... 2.x ...} using a location /api to forward all these calls to the CakePHP 4.x server
  • server {... 4.x ...} using a specific port (9090) to handle requests in CakePHP 4.x
  Using this approach, you can break your application into 2 parts, and start moving features by path to CakePHP 4. You'll need to handle the changes in 2 projects for a while, and pay this overhead,  but this could be better to maintain than a CakePHP 2.x application sitting on an old PHP version. Happy baking!  

Dependency Injection with CakePHP

Dependency Injection is some of the bigger buzzwords in PHP frameworks.  Historically, CakePHP application logic didn’t support that, until the version 4.2 was released last December. You can do that on your own and have a few plugins for that. This is a new chapter of the framework, let's see how to bake it.  

Use Case

First, let’s talk about a classic Use case on real applications. Our application will include an address form, such as the shipping address for an online order, or provide information about User, Company, etc. Autocomplete can help users supply the details.   We will use the Geocoding API from Google Maps Platform, making a HTTP request for API with json output format and address parameter: https://maps.googleapis.com/maps/api/geocode/json?address=89104&key=****** And here we go, we will get this result:  

Baking a Address Service

After seeing the Use case, all we need on our backend is to make a HTTP request for API and return the JSON result for the frontend to populate related fields.   1. First, let’s exposing our application for accept “.json” requests:   2. Now, we can bake a Address Controller and let’s request an empty result: $ ./bin/cake bake controller Address --actions index   Now our app requests /address.json will return an empty JSON.   3. Let’s bake (manually) the Address Service:   Basically I’m using Cake\Http\Client to make the API request. Also I read Geocode.key from Cake\Core\Configure, we don't want to expose our key on public requests (add the key on config/boostrap.php).   4. Let’s rewrite our Controller:   5. Finally, let’s add our Service on Application.php:   That’s all bakers! Now our endpoint /address.json will support query parameters and return the result of the API request.  

The cost of shiny

I’m here selling an idea and I don't start with the cons. Unfortunately, the Dependency Injection container is an experimental feature that is not API stable yet.  The support is a bit limited, CakePHP will inject services into: constructors of Controllers and Commands and Controller actions. The core team hopefully stabilizes the feature on version 4.3, or at most 4.4. They need your help testing and finding cases, and feedback always is welcome.   I hope this post can be useful for you and your projects.  See you next time!  

Planning For Your Upgrade

Having a successful upgrade implies not only upgrading the code itself, but also identifying the different tasks that will be part of the Upgrade Plan. Making a good plan for an upgrade requires identifying the current status of the application. A good plan is based upon clear, well-defined, and easily understood objectives.   After years of experience with CakeDC making upgrades, migrating applications from CakePHP 1 to CakePHP 4 in all possible combinations, we have noticed there are a set of elements or characteristics that are useful to evaluate and identify before starting the upgrade. Having a clear understanding of these elements will be helpful to define the different tasks that will be included in the Upgrade Plan, and reduce any risk while upgrading and delivering.   Imagine that you want to run a marathon - but before starting any of the thousands of plans you can find on the internet about “How to run a Marathon”, you must know where you are. You could ask yourself:  How many miles per week are you currently running? What is the base training needed to start this program? What is the distance of your longest run in the past 3 weeks? How many days per week do you have available to exercise?, etc. This will help you to choose the plan that better fits you. It’s important to identify where you are, where you want to get and how to get where you want.    Wondering how  to evaluate where you are for the Upgrade? Evaluate the status of your application. You could consider the following points as reference:

  • What is your current CakePHP version? 
  • Identify the weaknesses and the strength of the current code by making a code review.
  • Identify the versions of the packages, plugins, libraries that your application is using. 
  • If you are using CakePHP Third Party plugins, figure out if those plugins have already been upgraded.
  • Identify any third party integration and how the upgrade could affect it. 
  • What is the unit test coverage, if any? 
  • Is there any existing documentation?
  • Is there any custom change in the CakePHP core? (I hope there is not!)
  The complexity, time, cost, and resources required to upgrade your application will depend on the status of your application. Once you know where you are, it’s the time to plan how to get where you want.  Let’s talk about this in a future article. In case you are looking for some guidance on preparing your Upgrade Plan, don’t hesitate to contact us, we could help you to identify your current status, define the plan and execute the whole plan for you. We can also work together with your team on the upgrade, helping them understand the upgraded codebase so you can maintain the project with your own team as you did before.  

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