Migration plugins are the glue that binds a source, a destination, and multiple process plugins together to move data from one place to another. Often referred to as migration templates, or simply migrations, migration plugins are YAML files that explain to Drupal where to get the data, how to process it, and where to save the resulting object.

Source, process, and destination plugins do the heavy lifting in each phase of the ETL process in a custom migration. We need to choose which plugins we want to use for each phase, as well as map fields from our source data to fields at our destination. A migration YAML file glues it all together and gives it a unique name that we can use to run it.

In this tutorial we'll:

• Determine what information we're going to move, and where we're going to move it to
• Install Migrate Plus and Migrate Tools which we'll use to run our custom migration
• Write a custom migration plugin (configuration) YAML file that will work with Migrate Tools

By the end of this tutorial you should be able to write a custom migration YAML file and understand how to choose the source, destination, and process plugins that will do the work.

Before we can learn to write a custom migration, we need some sample data and a destination site for that data.

In this tutorial we'll obtain some source data to work with and configure our Drupal destination site by creating the necessary content types and fields to accommodate the source data. Then we'll look at the data that we'll be importing and start to formulate a migration plan.

By the end of this tutorial you'll have some source data and an empty but configured destination Drupal site ready for data import.

Destination plugins handle the load phase of the ETL (Extract, Transform, Load) process and are responsible for saving new data as Drupal content or configuration.

In this tutorial, we'll:

• Examine the role that destination plugins fulfill
• Learn about existing destination plugins
• Better understand when you might need to write your own destination plugin

By the end of this tutorial, you should be able to explain what destination plugins does and understand how you'll make use of them in your own migration.

Process plugins manipulate data during the transform phase of the ETL process while the data is being moved from the source to the destination. Drupal core provides a handful of common process plugins that can be used to perform the majority of data transformation tasks. If you need some functionality beyond what is already provided you can write your own custom process plugins.

In this tutorial we'll:

• Examine the role that process plugins fulfill
• Understand the processing pipeline
• List the existing process plugins in Drupal core and what each one does
• Better understand when you might need to write your own process plugin

By the end of this tutorial you should be able to explain what process plugins do, and understand how you'll make use of them in your own migration.

Source plugins extract data from a source and return it as a set of rows representing an individual item to import and some additional information about the properties that make up that row.

Anyone writing a custom migration, or module developers who want to provide a migration path from their Drupal 6 or 7 module, will need to work with source plugins.

In this tutorial we'll talk about the role that source plugins fulfill and how they work. By the end of this tutorial you should be able to determine whether or not you need to write a source plugin for your migration.

This tutorial covers writing a custom process plugin that you can use to manipulate the value of any field during the process (or transform) phase of a migration. Process plugins take an individual field value provided by a source plugin, and perform transformations on that data before passing it along to the load phase.

In this tutorial we'll write a process plugin that can either uppercase an entire string or the first letter of each word in the string depending on configuration.

By the end of this tutorial you should know how to start writing your own process plugins.

This tutorial covers writing a custom source plugin that imports data from a MySQL database into Drupal nodes. After completing this tutorial you should understand how to write your own custom source plugin that can:

• Extract data from an SQL source
• Describe the various fields in the source data to the Migrate API for mapping
• Provide unique IDs for each row of imported data

By the end of this tutorial you should be able write a custom source plugin that uses an SQL data store as well as have a foundation for writing source plugins that extract data from any source that PHP can read.

Anyone writing JavaScript for Drupal should use the Drupal.behaviors API when writing their custom JavaScript functionality. Doing so ensures that your JavaScript is executed at the appropriate times during the life cycle of a page, such as when the page loads, or after new DOM elements have been added via an AJAX request.

In this tutorial we'll look at:

• The problem that Drupal.behaviors solves
• How to use Drupal.behaviors when writing your JavaScript code

By the end of this tutorial you should be able to explain what the Drupal.behaviors API is, and be able to use it in your own JavaScript.

In Drupal, whenever we output markup it's best practice to use a Twig template or a theme function. But whenever you need to output DOM elements within JavaScript the best practice is to use the Drupal.theme function. This function ensures that the output can be overridden just like the HTML output by Twig. This tutorial covers how to use the Drupal.theme function in your JavaScript when inserting DOM elements, as well as how to replace the markup output by other JavaScript code that is using the Drupal.theme function.

ESLint is the linting tool of choice for JavaScript in Drupal. In this tutorial we’ll show how to install the ESLint application and then use it to verify that your JavaScript files are meeting the Drupal coding standards.

Drupal (as of version 8.4) has adopted the Airbnb JavaScript coding standards. In this tutorial, we'll walk through how to install the necessary package dependencies to run eslint on JavaScript files within your Drupal site.

It's often useful to pass dynamically calculated values from the server to the client in order to make them available to your front-end JavaScript. Your JavaScript might need to know something particular about the user currently visiting the site or the value of a particular configuration variable. In this tutorial, we'll look at how Drupal can pass these values from the PHP code that executes during a page load to the front-end JavaScript in your theme.

In order to do this, we'll need to:

• Explain how drupalSettings bridges the gap between PHP and JavaScript
• Generate values for settings in PHP and make them available to JavaScript
• Make use of PHP generated settings within your JavaScript code

Sometimes your JavaScript needs to insert new strings into the user interface. In order to ensure that those user-facing strings can be translated into other languages, just like the rest of Drupal's user interface, you should make sure and use the Drupal.t function anytime you output a string of text.

You may know that Drupal provides utility PHP functions for manipulating and sanitizing strings. Drupal also provides JavaScript functions for the same purpose. The two most useful are Drupal.checkPlain and Drupal.formatPlural. Drupal.checkPlain lets you ensure a string is safe for output into the DOM; it is useful when working with user-provided input. Drupal.formatPlural ensures that a string containing a count of items is pluralized correctly. This tutorial will show you where you can find documentation for and example use-cases of both.

Maybe you've heard of anonymous closures but you're not quite sure how they apply in Drupal, or why using them is considered a best-practice. Anonymous closures allow you to avoid accidentally clashing with anything in the global scope, as well as to alias the jQuery object to the more commonly used $. This is necessary because Drupal runs jQuery in no-conflict mode. This tutorial will look at the syntax used for placing your custom JavaScript code inside an anonymous closure, and why it's a good idea to do so.

In this tutorial we'll:

• Explain what a closure is (briefly), and what immediately invoked function expressions are
• Show how typically Drupal JavaScript gets wrapped in a closure
• Provide a copy/paste example you can use in your own code

By the end of this tutorial you should be able to explain what an anonymous closure is, and how to use one in your custom JavaScript for Drupal.