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"""Models."""
from astroid import Const
from astroid.nodes import Assign, AssignName, ClassDef, FunctionDef
from pylint.checkers import BaseChecker
from pylint_django.__pkginfo__ import BASE_ID
from pylint_django.compat import check_messages
from pylint_django.utils import PY3, node_is_subclass
MESSAGES = {
f"E{BASE_ID}01": (
"__unicode__ on a model must be callable (%s)",
"model-unicode-not-callable",
"Django models require a callable __unicode__ method",
),
f"W{BASE_ID}01": (
"No __unicode__ method on model (%s)",
"model-missing-unicode",
"Django models should implement a __unicode__ method for string representation",
),
f"W{BASE_ID}02": (
"Found __unicode__ method on model (%s). Python3 uses __str__.",
"model-has-unicode",
"Django models should not implement a __unicode__ method for string representation when using Python3",
),
f"W{BASE_ID}03": (
"Model does not explicitly define __unicode__ (%s)",
"model-no-explicit-unicode",
"Django models should implement a __unicode__ method for string representation. "
"A parent class of this model does, but ideally all models should be explicit.",
),
}
def _is_meta_with_abstract(node):
if isinstance(node, ClassDef) and node.name == "Meta":
for meta_child in node.get_children():
if not isinstance(meta_child, Assign):
continue
if not meta_child.targets[0].name == "abstract":
continue
if not isinstance(meta_child.value, Const):
continue
# TODO: handle tuple assignment?
# eg:
# abstract, something_else = True, 1
if meta_child.value.value:
# this class is abstract
return True
return False
def _has_python_2_unicode_compatible_decorator(node):
if node.decorators is None:
return False
for decorator in node.decorators.nodes:
if getattr(decorator, "name", None) == "python_2_unicode_compatible":
return True
return False
def _is_unicode_or_str_in_python_2_compatibility(method):
if method.name == "__unicode__":
return True
if method.name == "__str__" and _has_python_2_unicode_compatible_decorator(method.parent):
return True
return False
class ModelChecker(BaseChecker):
"""Django model checker."""
name = "django-model-checker"
msgs = MESSAGES
@check_messages("model-missing-unicode")
def visit_classdef(self, node): # noqa: PLR0911
"""Class visitor."""
if not node_is_subclass(node, "django.db.models.base.Model", ".Model"):
# we only care about models
return
for child in node.get_children():
if _is_meta_with_abstract(child):
return
if isinstance(child, Assign):
grandchildren = list(child.get_children())
if not isinstance(grandchildren[0], AssignName):
continue
name = grandchildren[0].name
if name != "__unicode__":
continue
grandchild = grandchildren[1]
assigned = grandchild.inferred()[0]
if assigned.callable():
return
self.add_message(f"E{BASE_ID}01", args=node.name, node=node)
return
if isinstance(child, FunctionDef) and child.name == "__unicode__":
if PY3:
self.add_message(f"W{BASE_ID}02", args=node.name, node=node)
return
# if we get here, then we have no __unicode__ method directly on the class itself
# a different warning is emitted if a parent declares __unicode__
for method in node.methods():
if method.parent != node and _is_unicode_or_str_in_python_2_compatibility(method):
# this happens if a parent declares the unicode method but
# this node does not
self.add_message(f"W{BASE_ID}03", args=node.name, node=node)
return
# if the Django compatibility decorator is used then we don't emit a warning
# see https://github.com/pylint-dev/pylint-django/issues/10
if _has_python_2_unicode_compatible_decorator(node):
return
if PY3:
return
self.add_message(f"W{BASE_ID}01", args=node.name, node=node)
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