Sets the constraints necessary during a model.save
call.
Finds the specific morphTo
table we should be working with, or throws
an error if none is matched.
If there are no arguments, return the current object's query builder (or create and return a new one). If there are arguments, call the query builder with the first argument, applying the rest. If the first argument is an object, assume the keys are query builder methods, and the values are the arguments for the query.
Helpers