If I two security_groups (say "A" and "B") or two floating_ip_network entries, and select the second one (i.e not the one that is rendered on page load) then the attribute is saved corectly to the db:

#<ComputeAttribute id: 2, compute_profile_id: 1, compute_resource_id: 7, name: "m1.tiny", vm_attrs: {"flavor_ref"=>"1", "image_ref"=>"9c9d4946-3e33-4f6e-92f0-f3527ef42862", "tenant_id"=>"e52297c4bf694c788c8bfb2b7792146b", "security_groups"=>"B", "network"=>"B"}, created_at: "2014-01-09 12:36:20", updated_at: "2014-01-09 12:50:46">]

But if I re-edit the profile (or try to create a host with it) I get the original, first enties in the form (i.e they are set to "A"). This means I have to go select "B" manually, negating the point of the profile.

This is probably related to the long-standing issue of the VM Tab not reloading correctly when Host#new is re-rendered after an error - a fix for that was wrapped up in larger changes in PR 1099. Perhaps it could be extracted and tested against this bug too?