Occasionally, I have come across Drupal sites that have base64 encoded images embedded into content fields. This is the approach of taking the binary data contained in a file and converting it into a string of characters. The original binary data can then be re-created using this string and the data is understood by lots of different technologies (including web browsers).

Whilst this is technically possible, it massively balloons the size of the database and can often slow down page load times due to the database being slow to respond to the request. Instead of fetching a few kilobytes of data from the table the database is forced to fetch many megabytes of data, which can create a bottleneck for other requests.

A recent challenge that I faced on a project was to generate the HTML of a full Drupal page, from within a Drupal request. The project called for a template to be rendered within the structure of a Drupal theme and also to include the styles associated with that theme.

At first, this doesn't seem like a big problem, but once I started trying to figure things out it became much more complex than I was expecting.

The problem is that you can't just render a page using the 'html' and 'page' templates as there is a lot of context surrounding those templates. Without this context in place Drupal produces a page of markup that contains no styles or blocks. The context is how Drupal knows what theme to load, what libraries to add to the page, what preprocess hooks to call, what menu items to generate, and so on.

I have written lots of detail about using update hooks to manage updates in Drupal and they have all been about the hook_update_N() hook. The hook_update_N() hook is just one of the options available in running updates as the update pipeline also includes hook_post_update_NAME(). The hook_deploy_NAME() hook, bundled with Drush 10, can also be used as an update hook in the same way.

Each of these update hooks has a number of different best practices when considering their use. All of these hooks are run once and once only and the key idea is that they take Drupal (or a module) from one version to another by adding database changes or configuration updates as the module gets updated.

For example, if you have a module that has a database table then it will be stored as schema information within your module. Once you release the module you must ensure that everyone who already has the module installed can still use it after the schema has changed. This means that as well as updating the schema information you also need to provide steps in the update hooks to update existing installs. Without this step the module would likely crash as it attempts to inject data into tables or fields that don't exist.

The Marp suite of tools is great for creating presentations from simple Markdown rules.

I've previously written about how to get up and running with Marp, but as I have been using it for a while I have come up with a few things that might be useful to know about if you are getting to grips with it.

Here's a list of what I'll be talking about.

1. Using HTML In Slides
2. Adding Speaker Notes
3. Using Spot Directives
4. Using Images
5. Generate A Presentation From A Document
6. Jump To A Slide
7. Creating Custom Themes

I was recently working with a Drupal 9 site and found some strange behaviour when saving certain types of content. The page would appear to save, but much of the content appeared to be missing. It had even failed to generate the paths for the page based on the path auto rules.

Digging deeper I found the root cause of the problem was an improperly created redirect in an insert hook within custom code written on the site. This code looked for the creation of a particular content type and then forced the redirect to happen.

Marp or Markdown Presentation Ecosystem is a collection of tools that allows the generation of presentations of different formats from a markdown template. The tools are written in JavaScript and have a number of options that allow presentations of different styles and formats.

This tools stood out to me as it has syntax highlighting built in and allows the creation of presentations using markdown. The presentation can also be altered using standard CSS styles.

I've spent many hours fiddling with presentations in Keynote and Google Slides, so I wanted something that would be simple to use and generate the presentation files I needed.

Generating a PDF document from a web page through PHP can be problematic. It's often something that seems quite simple, but actually generating the document can be difficult and time consuming.

There are a number of libraries available that allow you to generate PDF documents, but in reality they solve one problem and introduce several more. Packages exist as either HTML to PDF converters or allow you to generate a PDF by placing elements into the document.

Generating a PDF manually is not normally a good way to go just due to it being a very time consuming process and is difficult to test. You will probably have to spend time creating a rendering engine just for this purpose, and that will take time to create and maintain.

The lazy builder API in Drupal allows the creation of highly dynamic content within a render array without having to disable the cache for the entire render array or the page the content is attached to. What this means in real terms is that the initial render array can be cached quite heavily, but lazy builders allows for additional rendering to be done in after the initial rendering pass to generate content.

There are several reasons why lazy builders might be useful. The most useful reasons are to present some highly personalised or dynamic content to a user, but you might also want to offset the rendering of some slow code to give it some more fine grained caching that stores the outcome in a cache bucket.

Lazy builders work by using a normal render array, but instead of rendering the content you inject a lazy builder placeholder into the content. A callback method is used to tell Drupal how to inject the content into the placeholder.

The cache system in Drupal has a number of different components with time, contexts and tags being used to determine the cache.

Whilst all of these mechanisms are really useful you can also inject data directly into the cache system. This is beneficial if you have an expensive function that takes a long time to complete. The result of the function can be stored in the Drupal cache system just like other cache data.

For example, let's say you are pulling data from a slow API. If the data doesn't change much it might be better to add a cache to the request so that instead of going to the slow API the fast cache systems are used instead.

I was recently working on a Drupal form where I needed a user to select from a list of options that were available in a field attached to an entity. As the entity itself didn't exist when the user was filling in the form I needed a way of finding out the options that could be applied to the field. 

Getting a list of values from a field allows for numerous possibilities within Drupal, including configuring modules and creating wizards for generating content. As it took me a little while to track down how to do this I thought a quick post might come in handy for anyone looking to do the same.

In order to get the values available in a field we first need to create a blank entity. This will be used by the field storage system to load the correct field definitions.