97 lines
3.4 KiB
Markdown
97 lines
3.4 KiB
Markdown
---
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title: How to Define a Minimum Drupal Core Version
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date: 2015-04-03
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excerpt: How to define a minimum Drupal core version for your module or theme.
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tags:
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- drupal
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- drupal-7
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- drupal-planet
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meta:
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og:
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title: 'How to Define a Minimum Drupal Core Version'
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excerpt: 'How to define a minimum Drupal core version for your module or theme.'
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type: article
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---
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This week, my first code patch was
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[committed to Drupal core](https://www.drupal.org/node/2394517#comment-9773143).
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The patch adds the `user_has_role()` function to the user module, to simplify
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the way to check whether a user in Drupal has been assigned a specific role.
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This is something that I normally write a custom function for each project, but
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it's now available in Drupal core as of
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[7.36](https://www.drupal.org/drupal-7.36-release-notes).
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But what if someone is using a core version less than 7.36 and tries using the
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function? The site would return an error because that function wouldn't exist.
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If you're building a new Drupal site, then I'd assume that you're using a latest
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version of core, or you have the opportunity to update it when needed. But what
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if you're writing a contrib module? How can you be sure that the correct minimum
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version of core?
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## Setting Dependencies
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What I'm going to be doing for my contrib projects is defining a minimum version
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of Drupal core that the module is compatible with. If this dependency isn't met,
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the module won't be able to be enabled. This is done within your module's .info
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file.
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### Adding a Simple Dependency
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You can define a simple dependency for your module by adding a line this this to
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your project's .info file:
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```bash
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dependencies[] = views
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```
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This would make your module dependant on having the
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[Views](https://www.drupal.org/project/views) module present and enabled, which
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you'd need if you were including views as part of your module, for example.
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### Adding a Complex Dependency
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In the previous example, our module would enable if _any_ version of Views was
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enabled, but we need to specify a specific version. We can do this by including
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version numbers within the dependencies field in the following format:
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```bash
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dependencies[] = modulename (major.minor)
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```
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This can be a for a specific module release or a branch name:
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```bash
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dependencies[] = modulename (1.0)
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dependencies[] = modulename (1.x)
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```
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We can also use the following as part of the field for extra granularity:
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- = or == equals (this is the default)
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- > greater than
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- < lesser than
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- > = greater than or equal to
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- <= lesser than or equal to
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- != not equal to
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In the original scenario, we want to specify that the module can only be enabled
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on Drupal core 7.36 or later. To do this, we can use the "greater than or equal
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to" option.
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```ini
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dependencies[] = system (>=7.36)
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```
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Because we need to check for Drupal's core version, we're using the system
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module as the dependency and specifying that it needs to be either equal to or
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greater than 7.36. If this dependency is not met, e.g. Drupal 7.35 is being
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used, then the module cannot be enabled rather than showing a function not found
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error for `user_has_role()` when it is called.
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## External Links
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- [Writing module .info files (Drupal 7.x)](https://www.drupal.org/node/542202#dependencies)
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