def delete_object(instance):
"""Delete the data tables row for the given model instance"""
class_name = type(instance).__name__
Capability.require(instance.delete_capability, [class_name, instance.uid])
table = get_table(type(instance).__name__)
table.get(uid=instance.uid).delete()
def save_object(instance):
"""Persist an instance to the database by adding or updating a row"""
class_name = type(instance).__name__
table = get_table(class_name)
attributes = {
name: getattr(instance, name)
for name, attribute in instance._attributes.items()
}
single_relationships = {
name: _get_row(relationship.cls.__name__,
getattr(instance, name).uid)
for name, relationship in instance._relationships.items()
if not relationship.with_many and getattr(instance, name) is not None
}
multi_relationships = {
name: list(
_search_rows(
relationship.cls.__name__,
[
member.uid
for member in getattr(instance, name) if member is not None
],
))
for name, relationship in instance._relationships.items()
if relationship.with_many
}
members = {**attributes, **single_relationships, **multi_relationships}
cross_references = [{
"name": name,
"relationship": relationship
} for name, relationship in instance._relationships.items()
if relationship.cross_reference is not None]
has_permission = False
if instance.uid is not None:
if getattr(instance, "update_capability") is not None:
Capability.require(instance.update_capability,
[class_name, instance.uid])
has_permission = True
row = table.get(uid=instance.uid)
row.update(**members)
else:
raise ValueError(
"You do not have permission to update this object")
else:
if security.has_create_permission(class_name):
has_permission = True
uid = uuid4().hex
instance = copy(instance)
instance.uid = uid
row = table.add_row(uid=uid, **members)
if security.has_update_permission(class_name, uid):
instance.update_capability = Capability([class_name, uid])
if security.has_delete_permission(class_name, uid):
instance.delete_capability = Capability([class_name, uid])
else:
raise ValueError("You do not have permission to save this object")
if has_permission:
# Very simple cross reference update
for xref in cross_references:
# We only update the 'many' side of a cross reference
if not xref["relationship"].with_many:
xref_row = single_relationships[xref["name"]]
column_name = xref["relationship"].cross_reference
# We simply ensure that the 'one' side is included in the 'many' side.
# We don't cleanup any possibly redundant entries on the 'many' side.
if row not in xref_row[column_name]:
xref_row[column_name] += [row]
return instance