About bean of hasErrors - grails

Question

Assuming i have the following object in my controller
objCollection = [obj1, obj2, obj3]
And in each obj is the following
obj1 = [
input = value, inputA1 = valueA1, inputA2 = valueA2
]
obj2 = [
input = value, inputB2 = valueB2, inputA3 = valueA3
]
obj3 = [
input = value, inputC2 = valueC2, inputA3 = valueA3
]
And my GSP looks something like this
<div class="control-group ${hasErrors(bean: objCollection.obj, field: 'input', 'error')}">
<g:textField name='input' value='${objCollection?.obj}'>
</div>
<div id="subForm" class="subContainer">
<g:each var='obj' in='${objCollection}' status='a'>
<div id='obj${a+1}'>
<div class='subaccordion'>
<div>
<g:each var='objInstance' in='${obj}' status="b">
<g:render template="miniForm" model="[b:b, objInstance:objInstance]"/>
</g:each>
</div>
</div>
</div>
</g:each>
</div>
While for the template miniForm
<div class="control-group ${hasErrors(bean: objInstance, field: 'input', 'error')}">
<g:textField name='input' value='${objInstance?.obj}'>
</div>
<div class="control-group ${hasErrors(bean: objInstance, field: 'input', 'error')}">
<g:textField name='input' value='${objInstance?.obj}'>
</div>
Where the name attribute is changed using jquery to input A1, A2, B1, B2, C1 and C3 upon form load.
Now my question is, did i passed the object properly to the bean on hasErrors? Because i tried to get the hasErrors to work but somehow it didn't work to my expectation.
Did i made any mistake anywhere?
Also did i map the object correctly to every input in GSP? I'm not quite sure on how to use the safe operator '?' to avoid nullPointer error.