Extending SilverStripe modules extension - silverstripe

Question

I have installed a particular module in my SilverStripe installation. The following is the directory structure
- Root
- framework
- cms
- mymodule
- code
- extensions
- CustomClass.php
Here is an example of CustomClass.php
class CustomClass extends Extension {
public function init() {
}
public function customMethod() {
}
}
I need to override the customMethod method of the CustomClass class. I could easily change this method, but changing here will cause trouble in the future if the modules get updated. All the changes made will be lost.
So for this I want to extend the extension class used in modules.
I have created an extension /mysite/extensions/MyCustomClass.php
class MyCustomClass extends Extension {
public function customMethod() {
//do my code here
}
}
but I have no idea how to apply this. I thought CustomClass::add_extension("MyCustomClass ") but surely this will not work because add_extension method doesn't exist in CustomClass.
How do we cope with this scenario? Can I use Injector instead? If yes, how can it be called in mysite/_config.php instead of _config.yml?

Answer 1

Using injector does solve the problem but have to use _config.yml as well. Here is what I did.
File /mysite/extensions/MyCustomClass.php
class MyCustomClass extends CustomClass {
public function customMethod() {
//do my code here
}
}
in /mysite/_config/config.yml I added following lines
Injector:
CustomClass:
class: MyCustomClass
And in /mysite/_config.php I added following line
$object = Injector::inst()->create('CustomClass');
And it all worked fine.

Answer 2

There is another way to achieve similar functionality without straight up replacing a previous extension. With SilverStripe's extension system, we can control not only what configuration settings are loaded but the order they are loaded. This is important to note because the customMethod function from an extension, it uses the first one it finds from all the extensions loaded.
Because of this, it can be only a matter of controlling when your MyCustomClass extension is loaded so you can have your own customMethod function run.
Let's say the "MyModule" module has the following YAML file defined:
---
Name: MyModuleExtensions
After:
- 'framework/*'
- 'cms/*'
---
Page:
extensions:
- CustomClass
All we need to do is specify a separate YAML file to run before this "MyModule" one. This can be accomplished like:
---
Name: MyCustomModule
Before:
- MyModule/#MyModuleExtensions
---
Page:
extensions:
- MyCustomClass
Now, when you call your customMethod function on whatever class you have your extensions on (so in my example, the Page class), it will call the one from your MyCustomClass extension.