About Drupal 8 Migrate

The migrate module has been moved into the core in Drupal 8, showing the community dedicated to making the process of upgrading between versions or migrating into Drupal easier. The migrate module takes advantage of the Drupal 8 Plugin system, offering developers with several plugin types that they can implement: MigrateProcessPlugin, MigrateSourcePlugin, and MigrateDestinationPlugin.

Quick Recap of our previous blog:

  1. Complete rewrite & moved into Drupal 8 core
  2. Out of the box support for D6 -> D8 and D7 -> D8
    1. Nodes, Users, Comments, Profiles, Taxonomies
    2. Content & Configuration
  3. Support for custom sources and destinations
  4. Processors for working with/manipulating data

Series Mapping:

Part 1: Migration Setup & Mappings

Part 2: Working with Processors

Part 3: Coming soon!

Drupal 8 Migrate Module Overview

The Drupal 8 migrate module that is shipped with core provides a set of API’s for setting up migrations. The module also provides extensible object-oriented base classes and interfaces for migration plugins including:

  1. Source & Destination Plugins
  2. Process Plugins
  3. Config Migration Mappings

While the migrate module has been moved into core, the contributed space still provides significant value and I wouldn’t recommend trying to build a migration without it:

  1. Migrate Plus: The Migrate Plus project provides extensions to core migration framework functionality as well as examples.
  2. Migrate Tools: The Migrate Tools module provides tools for running and managing Drupal 8 migrations.

Creating Migration Mappings

In Drupal 8 all of your migration mappings are done through configuration files. In Drupal 7 these migration mappings would have been done in classes through the $this->addMapping() function.

Configuration files provide the blueprint for the migrations, and there are two main types of configuration files that we will need to define:

  1. migrate_plus.migrate_group.<name>.yml
  2. migrate_plus.migrate.<name>.yml

Migration Group

The migration group is a configuration file and is similar to the idea of hook_migrate_api in Drupal 7. This configuration file defines a group of migration classes and configures global configuration/settings to be shared across the classes.  

  1. id – Unique identifier
  2. shared_configuration – Defines shared configuration between all migration classes that are part of this group. **Example: setting the source database to use
  3. dependencies – Sets the dependencies for this set of migration classes to function

Let’s see an example:

Migration Configuration File

The migration configuration file is similar to a migration class in Drupal 7. At a high level, the migration config file defines the metadata and field mappings for a particular migration in Drupal 8. There are 5 key concepts that you need to be aware of in the migration configuration file:

  1. Definition – The definition of this migration class, its dependencies, and what migration_group it belongs to
  2. Source – What migration source should be used for this migration when it is run (i.e. where am I migrating my content from?)
  3. Destination – The destination for the migration (i.e. where am I migrating my content to?)
  4. Field Mappings – The mappings from Source -> Destination
    1. Processors – The processing of the source data so that it can be consumed by the destination

Let’s see an example:

Stay tuned for our next blog post in our migration series on custom processors. In this post, we will dive into what it takes to create a custom processor for a WordPress to Drupal migration.

Would you like help to create a more detailed plan for migrating your website to Drupal 8?

Contact Us – We would be happy to help!

As one of the top Drupal firms in the market, we get a lot of questions around Drupal 8 and its broad range of functionality, including Drupal 8 Batch Processing. We thought to start out the new year, we would offer our primer on Drupal 8 Batch Processing.

What is a batch job?

A batch job or batch processing is the execution of a series of jobs in a program on a computer without manual intervention (non-interactive). Strictly speaking, it is a processing mode: the execution of a series of programs each on a set or “batch” of inputs, rather than a single input.

In English, this means that it allows a computer program to break up a series of tasks into smaller chunks or pieces that run without any manual intervention to trigger.

When would I want to use this?

Drupal 8 Batch Processing jobs are valuable to use when there could be large amounts of data or long processes running that utilize a significant amount of memory. An example would be regenerating all URL aliases on your website. The “pathauto” module sets up a batch process when doing this to regenerate 25 aliases at a time, instead of trying to regenerate an entire site (think 5,000 – 500,000 entities) at one time that might cripple the system.

Why would I want to use this?

Performance & Scalability are the biggest reason to utilize Drupal 8 Batch Processing in your development. Batch jobs allow the processing of large amounts of data without relying on a single process to complete the task from start to finish in a single execution. This allows your server resources to be utilized in smaller chunks and freed up after each batch execution finishes.

Here are some questions you can ask when determining if you might need to create a batch process:

  1. Does the action I need to perform against these items have a per-item resource cost?
    • If the action your performing requires loading or processing of each item individually, you should be looking to use batch processing to handle it. If you are performing a simple task, such as a bulk DB query that impacts all nodes in your database, it may not be required.
  2. Do I need to perform an action on a large number of entities?
    • If the answer is yes, than you will likely gain significant performance benefits by utilizing batch processing to work through your task.
  3. Is there a finite set of data that I am performing actions on or can the dataset grow?
    • If you are unsure about how big your data set will get, you should strongly consider batch processing. Not planning for this upfront could cause site downtime and lots of headaches later down the road.
  4. Even if your current data set is small, can it expand?
    • For example, maybe your site only has 30 nodes at the moment, but that number will increase in the future. If this is the case, or you are building a module that you may want to contribute back to the community, you will likely want to look at batch processing as an option for handling this action.

How do I do this?

Creating a batch process in Drupal 8 is relatively straightforward. Here is what you will need to get started:

  • src/Controller/DemoBatchController.php
  • demo_batch.info.yml
  • demo_batch.routing.yml
  • demo_batch.mybatch.inc


The routing file defines a route, the Controller to be used, and the requirements to use it.


The controller tells Drupal what to do when the route (defined above) is accessed. In this case, we are creating a Batch Controller which will handle the processing of the batch job.


This includes file provides the callback functions for the controller to handle execution of the job. In this example, we are running through a migration task.

Looking for help with your Drupal 8 development? Contact Us to find out how we can help.