You can't just pass a list of instances like that in a link. You can however collect the ids into a list as a parameter and then use it to populate it later. For example:
<g:link controller="ServicioComunitario" action="generarDocDeReporte"
params="${[exportFormat:a, extesion:b, tgids: servicioLista.collect{it.id}.join(',')] }"
update="mainContent">Excel</g:link><br/>
And then in your controller where you need to get the list again:
def tg = ServicioComunitario.getAll(params?.tgids?.tokenize(","))
Also, you don't need to assign params
to params
when returning your model. parameters are already exposed in the GSP by convention.
[servicioComunitarioInstanceList: tg]