This module allows you to directly edit the fields of a related has_one object directly, without having to mess around with GridField or links to ModelAdmin. If the related has_one doesn't exist yet, then this module also creates the object and sets up the relation for you on first write.
This module has been tested editing a has_one in both a GridFieldDetailForm and on a generic Page in CMSMain.
SilverStripe 4.x.
Basic testing has been carried out on 4.0.x-dev. Extensive testing may be required as SS4 becomes more solid.
To use this module, simply add a field to the CMS fields for your object in your getCMSFields() method. The name of the field should be HasOneName-_1_-FieldName.
For example, say you have a has_one called Show and that has_one has a field called Title you want to edit. You'd add the field TextField::create('Show-_1_-Title', 'Show Title').
If you do not require that the outputted name of the field matches the value you supply, you can also use a colon as a separator instead of -_1_-.
To add support to your own forms, you need to add the SGN\HasOneEdit\UpdateFormExtension extension to your controller and call $this->extend('updateEditForm', $form) before returning the form to the template. Without this, the fields will not get populated with the values from the has_one though saving will work.