string, and the control type is set to
input-text. You can optionally set them if you want to change to another type:
one-to-one: The property is related to one object instance of the related model
one-to-many: The property contains list of object instances of the related model
many-to-many: The property contains list of object instances of the related model, and the related model may also have list of object instances of the current model.