[Sqlalchemy-tickets] Issue #3957: incorrect rendering of sqltext for column-level check constraint (zzzeek/sqlalchemy)

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

New issue 3957: incorrect rendering of sqltext for column-level check constraint
https://bitbucket.org/zzzeek/sqlalchemy/issues/3957/incorrect-rendering-of-sqltext-for-column

Michael Bayer:

```
#!python

from sqlalchemy import *
from sqlalchemy.sql.expression import ColumnClause

class CodenameConstraint(CheckConstraint):
    """Check that the column uses a limited alphabet."""
    def __init__(self, column_name):
        column = ColumnClause(column_name)
        super(CodenameConstraint, self).__init__(
            column.op("~")("^[A-Za-z0-9_-]+$"))


m = MetaData()
t = Table(
    't', m, Column('x', String, CodenameConstraint('x')),

)

from sqlalchemy.schema import CreateTable

print CreateTable(t)

```


a string compiler is being invoked separately, needs this:


```
#!diff

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 4415028..b18f903 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -2602,7 +2602,9 @@ class DDLCompiler(Compiled):
             formatted_name = self.preparer.format_constraint(constraint)
             if formatted_name is not None:
                 text += "CONSTRAINT %s " % formatted_name
-        text += "CHECK (%s)" % constraint.sqltext
+        text += "CHECK (%s)" % self.sql_compiler.process(constraint.sqltext,
+                                                         include_table=False,
+                                                         literal_binds=True)
         text += self.define_constraint_deferrability(constraint)
         return text
 

```

been this way for years so 1.2 to allow for any surprises.