I have a "profile" entity with a field "education" (to get started). That field contains various input fields that describe the "education". At the moment I have "institution" and "year". I created that field with the Field API in a dedicated module and attached it to my "profile" entity (currently this is a profile2 bundle). The entity form works as expected, the "education" field widget is included and I can add multiple "education" entries. I can view my entity and the fields get formatted, and I can edit my entity and the form widgets get rendered.
--profile entity ----education field ------education a --------institution a --------year a ------education b --------institution b --------year b
But I do not like the all or nothing approach here. There are going to be many different fields and I want to display the "profile" entity with various "edit" and "add new entry" buttons, which should load the specified field form widget via AJAX. The profile page on xing.com is a good example of what I am trying to achieve.
Is this possible with the fields form widget and Field API alone, or do I have to implement the ajax callback via a menu hook, which returns a form with the needed input fields? Can I even use my "education" field in that scenario or do I have to work with the entity API and database API?