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Add reverse_code optional argument to RunPython

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1 parent 15ed75d commit 6d3faba2d28f07f8cd7cf7aa91a6f8a555021d4f @andrewgodwin andrewgodwin committed Sep 25, 2013
Showing with 21 additions and 5 deletions.
  1. +21 −5 django/db/migrations/operations/special.py
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26 django/db/migrations/operations/special.py
@@ -107,18 +107,25 @@ class RunPython(Operation):
reduces_to_sql = False
reversible = False
- def __init__(self, code):
+ def __init__(self, code, reverse_code=None):
+ # Forwards code
if isinstance(code, six.string_types):
# Trim any leading whitespace that is at the start of all code lines
# so users can nicely indent code in migration files
code = textwrap.dedent(code)
# Run the code through a parser first to make sure it's at least
# syntactically correct
self.code = compile(code, "<string>", "exec")
- self.is_callable = False
else:
self.code = code
- self.is_callable = True
+ # Reverse code
+ if reverse_code is None:
+ self.reverse_code = None
+ elif isinstance(reverse_code, six.string_types):
+ reverse_code = textwrap.dedent(reverse_code)
+ self.reverse_code = compile(reverse_code, "<string>", "exec")
+ else:
+ self.reverse_code = reverse_code
def state_forwards(self, app_label, state):
# RunPython objects have no state effect. To add some, combine this
@@ -130,7 +137,7 @@ def database_forwards(self, app_label, schema_editor, from_state, to_state):
# object, representing the versioned models as an AppCache.
# We could try to override the global cache, but then people will still
# use direct imports, so we go with a documentation approach instead.
- if self.is_callable:
+ if six.callable(self.code):
self.code(models=from_state.render(), schema_editor=schema_editor)
else:
context = {
@@ -140,7 +147,16 @@ def database_forwards(self, app_label, schema_editor, from_state, to_state):
eval(self.code, context)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
- raise NotImplementedError("You cannot reverse this operation")
+ if self.reverse_code is None:
+ raise NotImplementedError("You cannot reverse this operation")
+ elif six.callable(self.reverse_code):
+ self.reverse_code(models=from_state.render(), schema_editor=schema_editor)
+ else:
+ context = {
+ "models": from_state.render(),
+ "schema_editor": schema_editor,
+ }
+ eval(self.reverse_code, context)
def describe(self):
return "Raw Python operation"

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