I am designing an application that will display dynamically-generated forms to the user who will then enter values into the form fields and submit those values for persistence. The form represents an employee evaluation.
One use case allows an administrator (from HR) to define the form fields. They should be able to create a new form, add/remove fields from a form and mark a form as ‘deleted’.
The second use case is when a manager views the form and enters values into the form fields for a specific employee. They should be able to save the values at any time and recall the saved values when viewing the form again for the same employee.
Finally, when the manager is satisfied with the values they’ve entered for that employee, they can ‘submit’ the form data which persists the flattened data into the data warehouse for reporting purposes. When this is done, the ‘working’ copy of the data is removed so the form will display empty the next time they view it for that employee.
I am not concerned with the front-end at this point and working on the back-end service application that sits between the client and the data store. The application must provide a course-grained interface for all of the behavior required.
My question is how many aggregate roots do I actually have (and from that, how many repositories, etc)? Do I separate the form definition from the form data even though I need both when displaying the form to the user?
I see two main entities, ‘EmployeeEvaluationSchema’ and ‘EmployeeEvaluation’. The ‘EmployeeEvaluationSchema’ entity would have a collection of ‘FieldDefinition’ value objects which would contain the properties that define a field, the most basic being the name of the field. The ‘EmployeeEvaluation’ entity would have a collection of ‘FieldValue’ value objects which contain the values for each field from the definition. In the simplest case, it would have a field name and value property. Next, the ‘EmployeeEvaluation’ could have a reference to ‘EmployeeEvaluationSchema’ to specify which definition the particular evaluation is based on. This can also be used to enforce the form definition in each evaluation. You would have two repositories – one for each entity. If you were to use an ORM such as NHibernate, then when you retrieve a ‘EmployeeEvaluation’ entity, the associated ‘EmployeeEvaluationSchema’ would also be retrieved even though there is a dedicated repository for it.