django-stubs/mypy_django_plugin/helpers.py

import typing
from typing import Dict, Optional

from mypy.nodes import MypyFile, TypeInfo, ImportedName, SymbolNode

MODEL_CLASS_FULLNAME = 'django.db.models.base.Model'
FOREIGN_KEY_FULLNAME = 'django.db.models.fields.related.ForeignKey'
ONETOONE_FIELD_FULLNAME = 'django.db.models.fields.related.OneToOneField'
MANYTOMANY_FIELD_FULLNAME = 'django.db.models.fields.related.ManyToManyField'
DUMMY_SETTINGS_BASE_CLASS = 'django.conf._DjangoConfLazyObject'

QUERYSET_CLASS_FULLNAME = 'django.db.models.query.QuerySet'
BASE_MANAGER_CLASS_FULLNAME = 'django.db.models.manager.BaseManager'
MANAGER_CLASS_FULLNAME = 'django.db.models.manager.Manager'
RELATED_MANAGER_CLASS_FULLNAME = 'django.db.models.manager.RelatedManager'

MANAGER_CLASSES = {
    MANAGER_CLASS_FULLNAME,
    RELATED_MANAGER_CLASS_FULLNAME,
    BASE_MANAGER_CLASS_FULLNAME,
    QUERYSET_CLASS_FULLNAME
}


def get_models_file(app_name: str, all_modules: typing.Dict[str, MypyFile]) -> Optional[MypyFile]:
    models_module = '.'.join([app_name, 'models'])
    return all_modules.get(models_module)


def get_model_fullname(app_name: str, model_name: str,
                       all_modules: Dict[str, MypyFile]) -> Optional[str]:
    models_file = get_models_file(app_name, all_modules)
    if models_file is None:
        # not imported so far, not supported
        return None
    sym = models_file.names.get(model_name)
    if not sym:
        return None

    if isinstance(sym.node, TypeInfo):
        return sym.node.fullname()
    elif isinstance(sym.node, ImportedName):
        return sym.node.target_fullname
    else:
        return None


class InvalidModelString(ValueError):
    def __init__(self, model_string: str):
        self.model_string = model_string


class SelfReference(ValueError):
    pass


def get_model_fullname_from_string(model_string: str,
                                   all_modules: Dict[str, MypyFile]) -> Optional[str]:
    if model_string == 'self':
        raise SelfReference()

    if '.' not in model_string:
        raise InvalidModelString(model_string)

    app_name, model_name = model_string.split('.')
    return get_model_fullname(app_name, model_name, all_modules)


def lookup_fully_qualified_generic(name: str, all_modules: Dict[str, MypyFile]) -> Optional[SymbolNode]:
    if '.' not in name:
        return None
    module, cls_name = name.rsplit('.', 1)

    module_file = all_modules.get(module)
    if module_file is None:
        return None
    sym = module_file.names.get(cls_name)
    if sym is None:
        return None
    return sym.node