Can somebody remove spammer batpurev...

A note to self (as I have tried to Google this before, and now I did it again, and most definitively will do it again):

For some reason SilverStripe does not look for field translations in the lang files automatically. Or if it does, I don't know how I should define the fields in the language files so that SilverStripe would find them. I'm using SilverStripe 3.6.1.

Anyway, here is a workaround. Put this to any class inherited from DataObject:

public function fieldLabel($name)
{
	$label = parent::fieldLabel($name);
	$label = _t($this->class.'.'.$name, $label); //Try to translate the field
	return $label;
}

And then you can translate your fields in your mysite/lang/en.yml (or whatever language file):

en:
  Title: MyTitle
  AnotherField: AnotherTranslation

Please do note that the fieldnames are case sensitive, so "Title", "AnotherField" or whatever you have must be written as-is. Also remember to run ?flush=all after editing your language file.

EDIT:

It seems that my workaround does not translate summary fields. But I found this:

http://www.balbuss.com/translating-statics-fields-and-labels/#TranslatingFieldlabels

class MyExample extends DataObject implements i18nEntityProvider {
 
static $db = array(
    'Name' => 'Varchar',
    ...
);
 
function fieldLabels($includerelations = true) {
    $labels = parent::fieldLabels($includerelations);
 
    // add a translation to the $labels array for each db field
    // if $includerelations == true (and it normally is) you need to add 
    // the db_ prefix, cause that's what SS will look for
    foreach($this->stat('db') as $key => $value) {
        $labels[$key] = _t("MyExample.db_{$key}", $key);
    }
 
    return $labels;
}