How do I sanitize form input in Silverstripe CMS

Question

Can someone please direct me to an example of how to sanitise a field from a dataObject BEFORE it gets dumped in the DB?

I don't know where to look.

I want to clean some user input before it is saved to the SiteConfig.

Answer 1

You can customize saving-behaviour of a Page, DataObject or SiteConfig using the onBeforeWrite function.

The function is triggered when calling write() to save the object to the database. This includes saving a page in the CMS or altering a ModelAdmin record.

Here is an example for Silverstripe 3.1 of using onBeforeWrite on a SiteConfig Extension to strip characters and convert characters to lowercase on a text field:

SiteConfig onBeforeWrite example

class CustomSiteConfig extends DataExtension {

    private static $db = array(
        'TwitterUsername' => 'Text'
    );

    public function updateCMSFields(FieldList $fields) {
        $fields->addFieldToTab('Root.Main', new TextField('TwitterUsername', 'Twitter Username'));
    }

    public function onBeforeWrite() {
        $this->owner->TwitterUsername = strtolower($this->owner->TwitterUsername);
        $this->owner->TwitterUsername = preg_replace("/[^a-z0-9]/", '', $this->owner->TwitterUsername);

        parent::onBeforeWrite();
    }
}

Note: For the above example to work the CustomSiteConfig extensions needs to be applied to the SiteConfig. This can either be done through a yml config file or through a _config.php file.

mysite/_config/config.yml

---
Name: site
After: 'framework/*','cms/*'
---

# ...

# SiteConfig Extension

SiteConfig:
  extensions:
    - CustomSiteConfig

# ...

Or

mysite/_config.php

global $project;
$project = 'mysite';

// ...

SiteConfig::add_extension('CustomSiteConfig');

// ...