Remarkably, I've just today tripped over this same exact
problem again. Turns out even using a post_save signal
callback function does not provide the information about
the new M2M data.
# callback for post_save signal, debug code removed for brevity
def ldap_netgroup_save(sender, **kwargs):
instance = kwargs['instance']
newng = kwargs['created']
cn = 'cn=%s,ou=Netgroup,%s' % (instance.name, base_dn)
connection = ldap.initialize(ldap_uri)
connection.simple_bind_s(bind_dn, bind_password)
if newng:
# WORKS
connection.add_s(cn, [('objectClass', 'nisNetgroup'),])
ifnames = []
for i in instance.interfaces.all():
ifnames = ifnames + make_nisnetgrouptriples(i.fqdn)
# HERE 'ifnames' is INCORRECTLY []
connection.modify_s(cn, [(ldap.MOD_REPLACE, 'nisNetgroupTriple',
ifnames),])
[NEW NETGROUP]*click*
Netgroup: foobar
Interfaces: I select 3
[SAVE]
DEBUG LOG:
Made new netgroup in LDAP: mynewnetgroup
saving interfaces as []
I view the netgroup in the admin interface and sure enough, all 3
'interfaces' are associated properly.
If I just click 'save' then it reports what it should
have reported when I made the new netgroup all along:
DEBUG LOG:
Existing netgroup in LDAP: mynewnetgroup
saving interfaces as ['(agilent,,)', '(agilent.our.org,,)',
'(ape,,)', '(ape.our.org,,)', '(aprh6test,,)',
'(aprh6test.our.org,,)']
This is such nonsense :(
On Jan 12, 12:20 pm, Jeff <[email protected]> wrote:
> On Jan 11, 9:23 pm, Dennis Lee Bieber <[email protected]> wrote:
>
> > On Wed, 11 Jan 2012 17:26:44 +0000, Tom Evans <[email protected]>
> > wrote:
>
> > >On Wed, Jan 11, 2012 at 5:22 PM, Jeff <[email protected]> wrote:
> > >> When Device.netgroups (a M2M field) changes, we need to perform
> > >> some python-ldap operations.
>
> > >Have you considered simply going back to the database to check what
> > >the values currently are? It would be inefficient, but clean and
> > >concise.
>
> > I've forgotten how many means of changing this data there are,
> > but...
>
> Dennis,
>
> Several.
>
> A web-only solution won't work.
>
> I found the 'm2m_changed' signal yesterday, read that you can't
> determine *what* changed by using it, and also ended up directed
> to some open bug reports... etc... and threw up my hands.
>
> To the best of my digging, there is no way to accurately tell
> in SomeModel.save() whether the previous value of MyM2MField
> and the new value are the same, and/or what the differences
> are.
>
> I ended up completely restructuring stuff (I'll spare you the
> details) so that I can just say "whatever .netgroups looks
> like AFTER save, make LDAP look exactly like that." This
> is essentially what Tom Evans suggested in his reply. It's
> inefficient, and clearly a workaround, but is at least doable.
>
> It boils down in LDAP-terms to saying "replace all attribute
> values for X with the following full data. I don't care what
> your old data was." ... instead of saying, "remove value Y
> from the 1000 values set on X" :|
>
> Thank you all for your efforts to help.
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