options.py 文件源码

def contribute_to_class(self, cls, name):
        from django.db import connection
        from django.db.backends.utils import truncate_name

        cls._meta = self
        self.model = cls
        # First, construct the default values for these options.
        self.object_name = cls.__name__
        self.model_name = self.object_name.lower()
        self.verbose_name = camel_case_to_spaces(self.object_name)

        # Store the original user-defined values for each option,
        # for use when serializing the model definition
        self.original_attrs = {}

        # Next, apply any overridden values from 'class Meta'.
        if self.meta:
            meta_attrs = self.meta.__dict__.copy()
            for name in self.meta.__dict__:
                # Ignore any private attributes that Django doesn't care about.
                # NOTE: We can't modify a dictionary's contents while looping
                # over it, so we loop over the *original* dictionary instead.
                if name.startswith('_'):
                    del meta_attrs[name]
            for attr_name in DEFAULT_NAMES:
                if attr_name in meta_attrs:
                    setattr(self, attr_name, meta_attrs.pop(attr_name))
                    self.original_attrs[attr_name] = getattr(self, attr_name)
                elif hasattr(self.meta, attr_name):
                    setattr(self, attr_name, getattr(self.meta, attr_name))
                    self.original_attrs[attr_name] = getattr(self, attr_name)

            self.unique_together = normalize_together(self.unique_together)
            self.index_together = normalize_together(self.index_together)

            # verbose_name_plural is a special case because it uses a 's'
            # by default.
            if self.verbose_name_plural is None:
                self.verbose_name_plural = string_concat(self.verbose_name, 's')

            # order_with_respect_and ordering are mutually exclusive.
            self._ordering_clash = bool(self.ordering and self.order_with_respect_to)

            # Any leftover attributes must be invalid.
            if meta_attrs != {}:
                raise TypeError("'class Meta' got invalid attribute(s): %s" % ','.join(meta_attrs.keys()))
        else:
            self.verbose_name_plural = string_concat(self.verbose_name, 's')
        del self.meta

        # If the db_table wasn't provided, use the app_label + model_name.
        if not self.db_table:
            self.db_table = "%s_%s" % (self.app_label, self.model_name)
            self.db_table = truncate_name(self.db_table, connection.ops.max_name_length())