For our equipment booking system we needed two kinds of content types: reservation and equipment. Patrons would create nodes of the reservation content type. Staff would create nodes of the equipment content type(s). Because our library circulates a lot of different equipment we need a bunch of content types — one for each: Apple TV, Laptop, iPad Air, Digital Video Camera, Projector, etc. The equiment content types all need the same field structure — title, description, image, accessories and equipment category. It’s tedious creating these individually, but once you get one fully fleshed out (and the skeletons of the rest in place) then the Field Sync module will finish the job with the push of a button.

The reservation content type would be canonical for each kind of equipment. In other words, we don’t have to create a Reservation_iPad and a Reservation_Laptop and a Reservation_Projector, etc. There’s just one: Reservation. The way we accomplish this is by using an entity reference field that looks for any nodes of equipment content types.

When a patron creates a node of the reservation content type, he/she will select the equipment to be reserved in the entity reference field. This entity reference structure allows us to offer a pretty helpful feature for patrons navigating from a specific equipment page to the reservation form. An Entity Reference Prepopulate and Display Suite combination gives us a “Reserve This Item” link on equipment pages (say Apple TV – Copy 1) that sends the patron to a node/add reservation page that has that piece of equipment (in this case Apple TV – Copy 1) selected in the equipment field.

There’s good documentation out there for Entity Reference Prepopulate — check out this video. But it might be worth explaining how we built the URL that prepoluates the entity reference field. With Display Suite you can create a custom code field — we hardcode a URL to the node/add reservation form, with a token for the id of the currently viewed entity appended onto it. When the user clicks the link, the Entity Reference Prepopulate module kicks off, sees the id and builds the form with that entity referenced.