[6.0 RC2] constraints can not be altered

[Ferdinand]

pls see/try extra-trunk/chricar_product_gtin
and see discussion here
https://bugs.launchpad.net/openobject-addons/+bug/697969
may be because of product_product inheritance ?

[xrg (xrg)]

Reported by Dr. Ferdinand Gassauer:
 "constraints can not be altered ..."

Indeed, when we define an expression like

class bar(osv.osv):
  _inherit = 'bar.bar'

  def _check_foo(self, cr, uid, ids, context):
      return True

  _constraints = [ (_check_foo, "Foo failed!", ['foo']) ]

... it means that _check_foo will be passed as an *object* to the model's
structure of _constraints. Therefore, it would be unequal and just append
the list of any existing constraints. So, an older (_check_foo, , ['foo'])
would always remain active using the previous code. This has to do with
the _check_foo being an unbound (ie. not inheritable) function.

Now, we check the /string name/ of the function, too. We say that if the
inherited class's constraint function has the same name "_check_foo", the
old ones shall be replaced.

Note: this MAY introduce unpredictable results, if several modules try
to override the same inherited constraint. There is no guaranteed order
of inheritance. Please avoid using this feature unless necessary.
---
 bin/osv/osv.py | 7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/bin/osv/osv.py b/bin/osv/osv.py
index 411dc0f..21a7e05 100644
--- a/bin/osv/osv.py
+++ b/bin/osv/osv.py
@@ -372,7 +372,12 @@ class osv(osv_base, orm.orm):
                                 exist = False
                                 for c2 in range(len(new)):
                                      #For _constraints, we should check field and methods as well
- if new[c2][2]==c[2] and new[c2][0]==c[0]:
+ if new[c2][2]==c[2] and (new[c2][0] == c[0] \
+ or getattr(new[c2][0],'__name__', True) == \
+ getattr(c[0],'__name__', False)):
+ # If new class defines a constraint with
+ # same function name, we let it override
+ # the old one.
                                         new[c2] = c
                                         exist = True
                                         break
--
1.7.1

[xrg (xrg)]

On Monday 10 January 2011, Ferdinand Gassauer wrote:
> Am Montag 10 Januar 2011, 12:11:33 schrieb P. Christeas:
>
> well isn't it the same for all inheritance - the last one wins ?

No. In members like _columns and _defaults (which are a dict), the named
items are updated. In _constraints, which is a list, they are just appended,
with that special fragment of code.

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[Ferdinand (office-chricar)]

well IMHO it's not logical (and to be expected) that constraints follow another rule (append instead of replace) - only because its a list and not a dict.
just my 2c

[Ferdinand (office-chricar)]

Applying the patch solves the problem - will it make it into v6?

[Olivier Dony (Odoo) (odo-openerp)]

xrg's patch was merged in server revision 3277 <email address hidden>, in time for v6.0.

Thanks for reporting!

[Satinderjit Singh (grewal-satinder)]

So, does it work with OpenERP 7 for anyone? We tried installing it on OpenERP 7, and it does not work.

[Martin Collins (mkc-steadfast)]

It doesn't work in 6.1, even though it has the patch (around line 900 in orm.py).
Apparently there is never anything in cls.__dict__.get('_constraints', []).

[Martin Collins (mkc-steadfast)]

It does work in 6.1. You have to override the _constraints list as well as the function, even if you don't want to change it.
Only then will it show up in cls.__dict__.get('_constraints', []).