Database Abstraction Layer for Drupal 7, 8, 9, and 10

Entity CRUD (Create, Read, Update, and Delete) operations are handled via the EntityTypeManager service.

In this tutorial we'll:

• Learn how to use the EntityTypeManager service to perform basic CRUD operations with examples you can copy/paste
• Access both property and field values of an entity
• Update entities by setting new field values and then saving the object

By the end of this tutorial, you'll be able to understand Entity CRUD operations and be well on your way to becoming comfortable with accessing and manipulating entity values in code.

Any Drupal module that provides custom database tables should implement hook_views_data() to describe the schema of those tables to Views. This hook is used to provide information to Views about the fields in a table, their human-readable names, and the types of data (string, integer, date, etc.) stored in each column. You can also tell Views how it should handle sorting, filtering, and formatting the data. Implementations of hook_views_data() can also be used to describe relationships between tables.

If you're creating a module that implements hook_schema() and adds new tables to the database it's a good idea to also add support for Views. Among other things, it'll allow administrators to create any user-facing displays of data from your table using Views. Then, they can be edited without having to write code. Once you've described your table to Views via hook_views_data() Views will be able to provide a way for administrators to construct queries against your data via the UI.

In this tutorial we'll:

• Use hook_views_data() to expose a custom table defined in a Drupal module to Views.
• Learn how to describe different types of data to Views.
• Demonstrate the relationship between hook_views_data() and what a site administrator has access to in the Views UI.

By the end of this tutorial you should know how to describe custom database tables and their fields to the Views module.

In this excerpt from the Overview of Drupal 7, Angie Byron, talks about the Database API in Drupal 7. This was a round table discussion with other Lullabots on the line who ask and answer questions, in addition to Angie's presentation. This lays a good foundation for how the database system works in Drupal and sets you up for the hands-on tutorials that follow.

Additional resources

Database API documentation

In this chapter we learn how to get data out of the database and display it. The example walks through writing a module that creates a page that displays how many nodes are published and unpublished for each content type in our site. We use the db_select() function to accomplish this.

In this chapter we learn how to create a new database table. This example walks through creating a module that defines the the properties of our new table and also programatically creating that table. We learn about hook_schema() and hook_update_N() in our module's install file.

Trainers note: This video starts out with a module that implements hook_node_view() and stores data about views in the $_SESSION variable. It also states that we built this earlier in the series. However, that's not true. We did talk about hook_node_view() in https://drupalize.me/videos/event-driven-hook-system, but we never actually wrote the $_SESSION handling part. So, if you're following along and want the same sample code we start with make sure you download the code attached to this node.

In this chapter we learn other ways to interact with our database beyond the simple db_select() query from the earlier video. This example walks through writing a module that that saves and displays data about how many times a user has visited a specific page. We learn about db_select(), db_insert(), db_update(), db_merge(), db_delete() and introduce the concept of "get and set" helper functions.