es we explained different aspects of the syntax used by the Migrate API. In today’s article, we are going to dive deeper to understand how the API interprets our migration definition files. We will explain how to configure process plugins and set subfields and deltas for multi-value field migrations. We will also talk about process plugin chains, source constants, pseudofields, and the process pipeline. After reading this article, you will better comprehend existing migration definition files and improve your own. Let’s get started.
In Drupal, a view is a listing of information. It can a list of nodes, users, comments, taxonomy terms, files, etc. A view scans your website using any criteria you specify and presents the results in the format of your choice. Example formats include a HTML table, a RSS feed, a PDF document, a CSV document, an interactive map, an image slideshow, or a JSON representation to be used as a REST endpoint. The same content can be presented in multiple formats at the same time. For instance, you can present a table of user information and on the same page a link to download the data in CSV format.
We have already talked about nodes, content types, and fields. In Drupal, they often comprise the main content of a page. Very likely you will want to display extra information along the page. This can be accomplished using containers called blocks. For example, the main content of a page can be a news article and a block can be used to display a list of other articles written by the same author. You could also use a block to show a search box or copyright text. Let’s explore what Drupal blocks have to offer.
After understanding the difference between nodes and content types, let’s learn a new concept. Fields are Drupal’s atomic data storage mechanism. They allow you to save discrete pieces of information which can be used for displaying, filtering, and sorting purposes.. Fields can be attached to nodes, users, taxonomy terms, blocks, and other Drupal entities. It is possible to share a field among bundles of the same entity. For example, you can share an image field among different content types (bundles) of the content (node) entity.
Node and content type are arguably the two most common concepts that we hear when starting to learn Drupal. Sometimes they are used interchangeably, but they represent different concepts. Let’s learn the difference and how they relate to one another. We are going to learn attributes that all nodes share, how content types can provide default values, and how content types serves as templates to collect different kinds of information.