Drupal 8 Messenger Service

7th February 2019 - 2 minutes read time

Note: This post is over a year old and so the information contained here might be out of date. If you do spot something please leave a comment and I will endeavour to correct.

For a long time the drupal_set_message() function has been a mainstay of Drupal development. You can use this function to print a message or an error response to a user. This is useful to do as it can be done almost anywhere before the final page rendering functions and will be printed into the same area of a Drupal page.

This has recently been deprecated in Drupal 8.5.0 and so I was looking around on how to do the same thing in a new way. Drupal now has a messenger service, powered by the class Drupal\Core\Messenger\Messenger. This can be included into your code using the following shortcut.

$messenger = \Drupal::messenger();

This can be used to print messages to the user. For example, to print a standard message with a blue background do the following.

$messenger->addMessage('Message printed to a user.');

This can be done in one line like this.

\Drupal::messenger()->addMessage('Message printed to a user.');

There are four different types of message available, each of which is printed with other messages of the same type and on a different coloured background.

// Green status message.
$messenger->addStatus('Print a status to the user.');
 
// Blue message.
$messenger->addMessage('Message printed to a user.');
 
// Yellow warning message.
$messenger->addWarning('A warning about something!');
 
// Red error message.
$messenger->addError('An error happened!');

If you are in a Drupal 8 Form's submitForm() handler then you can also get access to the messenger service through the form object.

$this->messenger()->addMessage($this->t('Form message.'));

If you are still using drupal_set_message() then I recommend that you swap to the messenger service soon as it will be removed in future versions of Drupal.

Drupal 8

Drupal

Drupal 9

Add new comment

Related Content

Drupal 9: Cascading Ajax Select Forms

Tying together different select elements in a form is done with very little effort thanks to the ajax and states system built into Drupal 9. This means that any Drupal form can have a select element that shows and updates options into another select element within the same form. Using this system you can create a hierarchical system where one select will show and populate another select element with items dependent on the first. This is great for giving the user the ability to drill down into options that are dependent on each other.

Drupal 9: Preventing Enumeration Attacks

A recent Wired article about the Parler data hack talked about how a hacker group was able to steal publicly available information from the Parler website using an Insecure Direct Object Reference (IDOR) or enumeration attack. This type of attack involves a hacker looking at the structure of the site and attempting to guess the next available resource by looking at the URL. Apparently, terabytes of Parler's data was downloaded by simply enumerating through the ID's of their publicly available posts.

Drupal 9: Auto Injecting Paragraph Forms On Node Edit Pages

I tried to do something the other day that I thought would be quite simple, but turned out to be really hard to get my head around. I had a Drupal 9 site with Paragraphs installed and I wanted a user to click a button on the node edit form and inject a particular Paragraph into a Paragraph field.

I found 2 solutions to this problem that solve it in slight different ways.

Drupal 9: Using Taxonomy Terms To Create A Related Content Views Block

For the last few years I have been tagging articles as I write them on this site. This tagging has largely been to tie posts together in an aggregated list of other posts tagged with that term. I recently wondered if I could use those tags to show related content below each article. I have struggled with this feature on client websites in the past and it either boils down to a manually curated list or some sort of complex content analysis and Solr search.

Drupal 8: Creating Custom Fields In Search API

Pushing data from Drupal into Solr is a really convenient way of creating a robust and extensible search solution. The Search API module has a number of different fields available that can be used to integrate with all sorts of fields, but what isn't included is computed fields or other data.

Thankfully, adding a custom field into the Search API system doesn't need a lot of code. A single class, with an optional hook, is all that's needed to het everything working.

Drupal 9: Integrating Flood Protection Into Forms

Drupal's login forms are protected by a protection mechanism that prevents brute force attacks. This means that if an attacker attempts to repeatedly guess a user's password to gain entry to their account they will be blocked before being successful. This system has been a part of Drupal for many years and so is battle tested.