[Sqlalchemy-tickets] Issue #3299: schematype constraints don't use naming convention if it doesnt include "constraint_name" (zzzeek/sqlalchemy)

[Mike B. <iss...@bi...>]

New issue 3299: schematype constraints don't use naming convention if it doesnt include "constraint_name"
https://bitbucket.org/zzzeek/sqlalchemy/issue/3299/schematype-constraints-dont-use-naming

Mike Bayer:

this is a little limiting.  due to #3067, the constraint convention below will not even be consulted:


```
#!python

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base

m1 = MetaData(naming_convention={"ck": "ck_%(table_name)s_%(column_0_name)s"})
Base = declarative_base(metadata=m1)

class A(Base):
    __tablename__ = 'a'
    id = Column(Integer, primary_key=True)
    foob = Column(BOOLEAN)

e = create_engine("mysql://scott:tiger@localhost/test", echo=True)
Base.metadata.drop_all(e)
Base.metadata.create_all(e)


```

this change needs to be made in order for it to be seen:

```
#!diff


diff --git a/lib/sqlalchemy/sql/naming.py b/lib/sqlalchemy/sql/naming.py
index 9e57418..21bf05d 100644
--- a/lib/sqlalchemy/sql/naming.py
+++ b/lib/sqlalchemy/sql/naming.py
@@ -114,8 +114,9 @@ def _constraint_name_for_table(const, table):
     if isinstance(const.name, conv):
         return const.name
     elif convention is not None and (
-        const.name is None or not isinstance(const.name, conv) and
-            "constraint_name" in convention
+        const.name is None or (
+            not isinstance(const.name, conv) or
+            "constraint_name" in convention)
     ):
         return conv(
             convention % ConventionDict(const, table,

```

there's no reason CheckConstraint can't have a .columns collection so that the columns_0_name convention can be useful.

I dont know that we want to change this for 0.9.