Change print $node_url To a Link Fields Value
If it is a field with in the node then you should be able to use the $node object. 

The object contains all the fields associated with the node. 

if you are not sure of the name of the field then you could try to print the object using the print_r function. 

You could also try try the $content object which contains the fields as well. 

print render($content['field_viewslink']);


That should render the variable.