Sure enough, this worked just as he said. I was somehow under the impression that each instance variable of the bean had to have one getter and one setter, like it was a required part of the bean specification. It turns out that this isn't exactly correct, I commented out the set() method and it automatically turns the bound input to read only. I never had learned this before so I thought it worthy of sharing. Of course the nice side benefit of blogging this, is that I am now 10x more likely to remember this.
The logic for a computed field goes in the Get() method. For some reason I was thinking the opposite. To make the value dynamic, I put the computed value in a different container than the editable fields, and did a partial refresh of the container in the onChange event of each input field used in the calculation. I really like the result. All of this amounted to an additional six lines of java code in a method that I already had.
To create a dynamic field in summary:
- Bind directly to the bean using expression language. If you are using beans, then you are likely already doing this. I used an 'Edit Box' to store my 'computed field'.
- Comment out or remove the set----() method in the bean
- Put your business logic in the get----() method of the bean
- Put your dynamic field(s) in a different container element
- Refresh the container element using partial refresh