refactor: add revision context to AutogenerateDiffsDetected so that w…

…rappers may make other formatting of the diff

fixes: sqlalchemy#1597

alembic/command.py

@@ -298,7 +298,9 @@ def retrieve_migrations(rev, context):
 
     if diffs:
         raise util.AutogenerateDiffsDetected(
-            f"New upgrade operations detected: {diffs}"
+            f"New upgrade operations detected: {diffs}",
+            revision_context=revision_context,
+            diffs=diffs,
         )
     else:
         config.print_stdout("No new upgrade operations detected.")

alembic/util/exc.py

@@ -1,6 +1,25 @@
+from __future__ import annotations
+
+from typing import Any
+from typing import List
+from typing import Tuple
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from alembic.autogenerate import RevisionContext
+
+
 class CommandError(Exception):
     pass
 
 
 class AutogenerateDiffsDetected(CommandError):
-    pass
+    def __init__(
+        self,
+        message: str,
+        revision_context: RevisionContext,
+        diffs: List[Tuple[Any, ...]],
+    ) -> None:
+        super().__init__(message)
+        self.revision_context = revision_context
+        self.diffs = diffs

docs/build/unreleased/issue1597.rst

@@ -0,0 +1,6 @@
+ .. change::
+        :tags: check, autogenerate
+        :tickets: 1597
+
+        Add revision context to AutogenerateDiffsDetected so that command can be wrapped and diffs may be output in a different format.
+        Pull request courtesy of Louis-Amaury Chaib (@lachaib).