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|
from contextlib import contextmanager
from unittest import mock
import django
from django.db.migrations import (
AddField,
AlterField,
CreateModel,
DeleteModel,
RemoveField,
RenameField,
)
from django.db.migrations.autodetector import MigrationAutodetector
from django.db.migrations.operations.fields import FieldOperation
from psqlextra.models import (
PostgresMaterializedViewModel,
PostgresPartitionedModel,
PostgresViewModel,
)
from psqlextra.types import PostgresPartitioningMethod
from . import operations
from .state import (
PostgresMaterializedViewModelState,
PostgresPartitionedModelState,
PostgresViewModelState,
)
# original `MigrationAutodetector.add_operation`
# function, saved here so the patched version can
# call the original
add_operation = MigrationAutodetector.add_operation
class AddOperationHandler:
"""Handler for when operations are being added to a new migration.
This is where we intercept operations such as
:see:CreateModel to replace it with our own.
"""
def __init__(self, autodetector, app_label, args, kwargs):
self.autodetector = autodetector
self.app_label = app_label
self.args = args
self.kwargs = kwargs
def add(self, operation):
"""Adds the specified operation to the list of operations to execute in
the migration."""
return add_operation(
self.autodetector,
self.app_label,
operation,
*self.args,
**self.kwargs,
)
def add_field(self, operation: AddField):
"""Adds the specified :see:AddField operation to the list of operations
to execute in the migration."""
return self._transform_view_field_operations(operation)
def remove_field(self, operation: RemoveField):
"""Adds the specified :see:RemoveField operation to the list of
operations to execute in the migration."""
return self._transform_view_field_operations(operation)
def alter_field(self, operation: AlterField):
"""Adds the specified :see:AlterField operation to the list of
operations to execute in the migration."""
return self._transform_view_field_operations(operation)
def rename_field(self, operation: RenameField):
"""Adds the specified :see:RenameField operation to the list of
operations to execute in the migration."""
return self._transform_view_field_operations(operation)
def _transform_view_field_operations(self, operation: FieldOperation):
"""Transforms operations on fields on a (materialized) view into state
only operations.
One cannot add/remove/delete fields on a (materialized) view,
however, we do want Django's migration system to keep track of
these kind of changes to the model. The :see:ApplyState
operation just tells Django the operation was applied without
actually applying it.
"""
if django.VERSION >= (4, 0):
model_identifier = (self.app_label, operation.model_name.lower())
model_state = (
self.autodetector.to_state.models.get(model_identifier)
or self.autodetector.from_state.models[model_identifier]
)
if isinstance(model_state, PostgresViewModelState):
return self.add(
operations.ApplyState(state_operation=operation)
)
else:
model = self.autodetector.new_apps.get_model(
self.app_label, operation.model_name
)
if issubclass(model, PostgresViewModel):
return self.add(
operations.ApplyState(state_operation=operation)
)
return self.add(operation)
def add_create_model(self, operation: CreateModel):
"""Adds the specified :see:CreateModel operation to the list of
operations to execute in the migration."""
if django.VERSION >= (4, 0):
model_state = self.autodetector.to_state.models[
self.app_label, operation.name.lower()
]
if isinstance(model_state, PostgresPartitionedModelState):
return self.add_create_partitioned_model(operation)
elif isinstance(model_state, PostgresMaterializedViewModelState):
return self.add_create_materialized_view_model(operation)
elif isinstance(model_state, PostgresViewModelState):
return self.add_create_view_model(operation)
else:
model = self.autodetector.new_apps.get_model(
self.app_label, operation.name
)
if issubclass(model, PostgresPartitionedModel):
return self.add_create_partitioned_model(operation)
elif issubclass(model, PostgresMaterializedViewModel):
return self.add_create_materialized_view_model(operation)
elif issubclass(model, PostgresViewModel):
return self.add_create_view_model(operation)
return self.add(operation)
def add_delete_model(self, operation: DeleteModel):
"""Adds the specified :see:Deletemodel operation to the list of
operations to execute in the migration."""
if django.VERSION >= (4, 0):
model_state = self.autodetector.from_state.models[
self.app_label, operation.name.lower()
]
if isinstance(model_state, PostgresPartitionedModelState):
return self.add_delete_partitioned_model(operation)
elif isinstance(model_state, PostgresMaterializedViewModelState):
return self.add_delete_materialized_view_model(operation)
elif isinstance(model_state, PostgresViewModelState):
return self.add_delete_view_model(operation)
else:
model = self.autodetector.old_apps.get_model(
self.app_label, operation.name
)
if issubclass(model, PostgresPartitionedModel):
return self.add_delete_partitioned_model(operation)
elif issubclass(model, PostgresMaterializedViewModel):
return self.add_delete_materialized_view_model(operation)
elif issubclass(model, PostgresViewModel):
return self.add_delete_view_model(operation)
return self.add(operation)
def add_create_partitioned_model(self, operation: CreateModel):
"""Adds a :see:PostgresCreatePartitionedModel operation to the list of
operations to execute in the migration."""
if django.VERSION >= (4, 0):
model_state = self.autodetector.to_state.models[
self.app_label, operation.name.lower()
]
partitioning_options = model_state.partitioning_options
else:
model = self.autodetector.new_apps.get_model(
self.app_label, operation.name
)
partitioning_options = model._partitioning_meta.original_attrs
_, args, kwargs = operation.deconstruct()
if partitioning_options["method"] != PostgresPartitioningMethod.HASH:
self.add(
operations.PostgresAddDefaultPartition(
model_name=operation.name, name="default"
)
)
partitioned_kwargs = {
**kwargs,
"partitioning_options": partitioning_options,
}
self.add(
operations.PostgresCreatePartitionedModel(
*args,
**partitioned_kwargs,
)
)
def add_delete_partitioned_model(self, operation: DeleteModel):
"""Adds a :see:PostgresDeletePartitionedModel operation to the list of
operations to execute in the migration."""
_, args, kwargs = operation.deconstruct()
return self.add(
operations.PostgresDeletePartitionedModel(*args, **kwargs)
)
def add_create_view_model(self, operation: CreateModel):
"""Adds a :see:PostgresCreateViewModel operation to the list of
operations to execute in the migration."""
if django.VERSION >= (4, 0):
model_state = self.autodetector.to_state.models[
self.app_label, operation.name.lower()
]
view_options = model_state.view_options
else:
model = self.autodetector.new_apps.get_model(
self.app_label, operation.name
)
view_options = model._view_meta.original_attrs
_, args, kwargs = operation.deconstruct()
view_kwargs = {**kwargs, "view_options": view_options}
self.add(operations.PostgresCreateViewModel(*args, **view_kwargs))
def add_delete_view_model(self, operation: DeleteModel):
"""Adds a :see:PostgresDeleteViewModel operation to the list of
operations to execute in the migration."""
_, args, kwargs = operation.deconstruct()
return self.add(operations.PostgresDeleteViewModel(*args, **kwargs))
def add_create_materialized_view_model(self, operation: CreateModel):
"""Adds a :see:PostgresCreateMaterializedViewModel operation to the
list of operations to execute in the migration."""
if django.VERSION >= (4, 0):
model_state = self.autodetector.to_state.models[
self.app_label, operation.name.lower()
]
view_options = model_state.view_options
else:
model = self.autodetector.new_apps.get_model(
self.app_label, operation.name
)
view_options = model._view_meta.original_attrs
_, args, kwargs = operation.deconstruct()
view_kwargs = {**kwargs, "view_options": view_options}
self.add(
operations.PostgresCreateMaterializedViewModel(
*args,
**view_kwargs,
)
)
def add_delete_materialized_view_model(self, operation: DeleteModel):
"""Adds a :see:PostgresDeleteMaterializedViewModel operation to the
list of operations to execute in the migration."""
_, args, kwargs = operation.deconstruct()
return self.add(
operations.PostgresDeleteMaterializedViewModel(*args, **kwargs)
)
@contextmanager
def patched_autodetector():
"""Patches the standard Django :seee:MigrationAutodetector for the duration
of the context.
The patch intercepts the `add_operation` function to
customize how new operations are added.
We have to do this because there is no way in Django
to extend the auto detector otherwise.
"""
autodetector_module_path = "django.db.migrations.autodetector"
autodetector_class_path = (
f"{autodetector_module_path}.MigrationAutodetector"
)
add_operation_path = f"{autodetector_class_path}.add_operation"
def _patched(autodetector, app_label, operation, *args, **kwargs):
handler = AddOperationHandler(autodetector, app_label, args, kwargs)
if isinstance(operation, CreateModel):
return handler.add_create_model(operation)
if isinstance(operation, DeleteModel):
return handler.add_delete_model(operation)
if isinstance(operation, AddField):
return handler.add_field(operation)
if isinstance(operation, RemoveField):
return handler.remove_field(operation)
if isinstance(operation, AlterField):
return handler.alter_field(operation)
if isinstance(operation, RenameField):
return handler.rename_field(operation)
return handler.add(operation)
with mock.patch(add_operation_path, new=_patched):
yield
|
