From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 11 Dec 2013 19:30:18 +0000 (-0500)
Subject: - The :class:`.exc.StatementError` or DBAPI-related subclass
X-Git-Tag: rel_0_9_0~40^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9087157749a0527d6af37e58166793fc7e2f0bf7;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

- The :class:`.exc.StatementError` or DBAPI-related subclass
now can accomodate additional information about the "reason" for
the exception; the :class:`.Session` now adds some detail to it
when the exception occurs within an autoflush.  This approach
is taken as opposed to combining :class:`.FlushError` with
a Python 3 style "chained exception" approach so as to maintain
compatibility both with Py2K code as well as code that already
catches ``IntegrityError`` or similar.
---

diff --git a/doc/build/changelog/changelog_09.rst b/doc/build/changelog/changelog_09.rst
index e658e6928f..fa1006694d 100644
--- a/doc/build/changelog/changelog_09.rst
+++ b/doc/build/changelog/changelog_09.rst
@@ -14,6 +14,18 @@
 .. changelog::
     :version: 0.9.0b2
 
+    .. change::
+        :tags: feature, orm
+
+        The :class:`.exc.StatementError` or DBAPI-related subclass
+        now can accomodate additional information about the "reason" for
+        the exception; the :class:`.Session` now adds some detail to it
+        when the exception occurs within an autoflush.  This approach
+        is taken as opposed to combining :class:`.FlushError` with
+        a Python 3 style "chained exception" approach so as to maintain
+        compatibility both with Py2K code as well as code that already
+        catches ``IntegrityError`` or similar.
+
     .. change::
         :tags: feature, postgresql
         :pullreq: bitbucket:8
diff --git a/lib/sqlalchemy/exc.py b/lib/sqlalchemy/exc.py
index 3c0c6c3657..93722fe998 100644
--- a/lib/sqlalchemy/exc.py
+++ b/lib/sqlalchemy/exc.py
@@ -219,6 +219,10 @@ class StatementError(SQLAlchemyError):
         self.statement = statement
         self.params = params
         self.orig = orig
+        self.detail = []
+
+    def add_detail(self, msg):
+        self.detail.append(msg)
 
     def __reduce__(self):
         return self.__class__, (self.args[0], self.statement,
@@ -227,8 +231,13 @@ class StatementError(SQLAlchemyError):
     def __str__(self):
         from sqlalchemy.sql import util
         params_repr = util._repr_params(self.params, 10)
-        return ' '.join((SQLAlchemyError.__str__(self),
-                         repr(self.statement), repr(params_repr)))
+
+        return ' '.join([
+                            "(%s)" % det for det in self.detail
+                        ] + [
+                            SQLAlchemyError.__str__(self),
+                             repr(self.statement), repr(params_repr)
+                        ])
 
     def __unicode__(self):
         return self.__str__()
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 553f6de972..b3720c94e2 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1180,7 +1180,18 @@ class Session(_SessionClassMethods):
 
     def _autoflush(self):
         if self.autoflush and not self._flushing:
-            self.flush()
+            try:
+                self.flush()
+            except sa_exc.StatementError as e:
+                # note we are reraising StatementError as opposed to
+                # raising FlushError with "chaining" to remain compatible
+                # with code that catches StatementError, IntegrityError,
+                # etc.
+                e.add_detail(
+                        "raised as a result of Query-invoked autoflush; "
+                        "consider using a session.no_autoflush block if this "
+                        "flush is occuring prematurely")
+                util.raise_from_cause(e)
 
     def refresh(self, instance, attribute_names=None, lockmode=None):
         """Expire and refresh the attributes on the given instance.