Repository: django/django
File: django/db/models/query.py (Python)

Code before:
            return False

        if not self.ordered:
            return False

        ordering = self.query.order_by
        if not ordering and self.query.default_ordering:
            ordering = self.query.get_meta().ordering

        if not ordering:
            return False

        opts = self.model._meta
        pk_fields = {f.attname for f in opts.pk_fields}
        ordering_fields = set()

        for part in ordering:
            # Search for single field providing a total ordering.
            field_name = None
            if isinstance(part, str):
                field_name = part.lstrip("-")
            elif isinstance(part, F):
                field_name = part.name
            elif isinstance(part, OrderBy) and isinstance(part.expression, F):
                field_name = part.expression.name

            if field_name:
                if field_name == "pk":
                    return True
                try:
                    field = opts.get_field(field_name)
                except exceptions.FieldDoesNotExist:
                    continue

                if field.remote_field and field_name == field.name:
                    continue
                if field.attname in pk_fields and len(pk_fields) == 1:
                    return True
                if field.unique and not field.null:
                    return True
                ordering_fields.add(field.attname)

        # Account for members of a CompositePrimaryKey.
        if ordering_fields.issuperset(pk_fields):
            return True

        # Try unique_together and total unique constraints.
        constraint_field_names = (
            *opts.unique_together,
            *(constraint.fields for constraint in opts.total_unique_constraints),
        )

Review comment (suggestion):
Still missing comments from the original version like the one "Could be "?" ..."

Please check them all.

Code after:
        if not self.ordered:
            return False
        ordering = self.query.order_by
        if not ordering and self.query.default_ordering:
            ordering = self.query.get_meta().ordering
        if not ordering:
            return False
        opts = self.model._meta
        pk_fields = {f.attname for f in opts.pk_fields}
        ordering_fields = set()
        for part in ordering:
            # Search for single field providing a total ordering.
            field_name = None
            if isinstance(part, str):
                field_name = part.lstrip("-")
            elif isinstance(part, F):
                field_name = part.name
            elif isinstance(part, OrderBy) and isinstance(part.expression, F):
                field_name = part.expression.name
            if field_name:
                if field_name == "pk":
                    return True
                # Normalize attname references by using get_field().
                try:
                    field = opts.get_field(field_name)
                except exceptions.FieldDoesNotExist:
                    # Could be "?" for random ordering or a related field
                    # lookup. Skip this part of introspection for now.
                    continue
                # Ordering by a related field name orders by the referenced
                # model's ordering. Skip this part of introspection for now.
                if field.remote_field and field_name == field.name:
                    continue
                if field.attname in pk_fields and len(pk_fields) == 1:
                    return True
                if field.unique and not field.null:
                    return True
                ordering_fields.add(field.attname)

        # Account for members of a CompositePrimaryKey.
        if ordering_fields.issuperset(pk_fields):
            return True
        # No single total ordering field, try unique_together and total
        # unique constraints.
        constraint_field_names = (
            *opts.unique_together,
            *(constraint.fields for constraint in opts.total_unique_constraints),
        )
        for field_names in constraint_field_names:
            # Normalize attname references by using get_field().
            try: