I'm new to Grails development, and I'm wondering what the standard way of handling this problem is:
In a GSP, I'm iterating over a list of domain objects, many, but not all of which have a getX() method. I want to a tag that looks like this:
<g:each in="${myObjects}>
${it.x}
</g:each>
However, since some of my object don't have a getX method, I am getting a 'No such property' exception. I would like it if there was some sort of operator like the 'safe operator' that prevents NPEs. Is there good way of handling this without doing an 'instanceof'?
I'm afraid Groovy's operators wont help you here. The safe navigation operator (?.) would help you if the reference on which you want to call a method could be null; and the Elvis operator (?:) would help you if your x property would be a property of all the objects, except that for some of them it might be null (something like it.x ?: 'no x here').
In this case --i assume you are working with a collection of objects of different classes, some of them which do not have an x property-- you may ask the object if it has the property x (notice that if the object implements a method called getX, then it.hasProperty('x') will be true):
<g:each in="${myObjects}>
${it.hasProperty('x') ? it.x : 'no x here'}
</g:each>
Replace the 'no x here' bit with whatever your fallback value might be. Also, you might consider using the <g:if>/<g:else> tags instead of the ternary operator if the logic for both options is more complicated than a simple expression :)