What are good design patterns for dynamic visualforce components for a data-driven input form?

Question

I am designing a custom input form that will be data-driven and will display things like input fields, input text components, custom inputs that I create, etc. The elements on the form will be largely data-driven so I could create it with dynamic vf binding like so:

<apex:repeat... var="inputobj">
  <apex:outputpanel rendered="{!inputobj.type == 'standardinputfield'}"
    <apex:inputField required="{!inputobj.isRequired}" value="{!inputobj.data[f.apiName]}"
  </apex:outputpanel}"
  <apex:outputpanel rendered="{!inputobj.type == 'something'}"
  ...
  </apex:outputpanel}" 
  <apex:outputpanel rendered="{!inputobj.type == 'something else'}"
  ...
  </apex:outputpanel}"
  ...
</apex:repeat>

I've used this pattern in the past and it works reasonably well but the vf becomes quite unwieldy as you create more types (both from a development and performance perspective) and you can't really reuse and extend the vf like you can with abstract and virtual classes.

My idea is that the inputobjects will have a method which generates a dynamic vf component for itself and then just repeat over those components. Has anyone built something similar or run into any issues with this?

My main concern is ending up with an unholy mess of UI mixed in with business logic or running into performance issues with dynamic vf components.

Answer 1

I think the first things you should look to use are Dynamic Visualforce Components. The introduction of this feature was meant to address some of the challenges that you are facing. This allows you to simplify your Visualforce markup by moving the logic of the markup (view) rendering to your Apex Controller. Some will argue that this is bad because it mixes View responsibilities into your Controller, thus breaking the MVC design, but this can also be a really powerful feature if used appropriately.

There is a good example here of returning a outputPanel from the controller.

Aside from this, you can also look to create some of your own Visualforce Components to keep your markup pages a little cleaner.