Function _validate_value

dash/_validate.py:274–333

(val, index=None)

        return True

    def _validate_value(val, index=None):
        # val is a Component
        if isinstance(val, Component):
            unserializable_items = []
            # pylint: disable=protected-access
            for p, j in val._traverse_with_paths():
                # check each component value in the tree
                if not _valid_child(j):
                    _raise_invalid(bad_val=j, outer_val=val, path=p, index=index)

                if not _can_serialize(j):
                    # collect unserializable items separately, so we can report
                    # only the deepest level, not all the parent components that
                    # are just unserializable because of their children.
                    unserializable_items = [
                        i for i in unserializable_items if not p.startswith(i[0])
                    ]
                    if unserializable_items:
                        # we already have something unserializable in a different
                        # branch - time to stop and fail
                        break
                    if all(not i[0].startswith(p) for i in unserializable_items):
                        unserializable_items.append((p, j))

                # Children that are not of type Component or
                # list/tuple not returned by traverse
                child = getattr(j, "children", None)
                if not isinstance(child, (tuple, MutableSequence)):
                    if child and not _can_serialize(child):
                        _raise_invalid(
                            bad_val=child,
                            outer_val=val,
                            path=p + "\n" + "[*] " + type(child).__name__,
                            index=index,
                        )
            if unserializable_items:
                p, j = unserializable_items[0]
                # just report the first one, even if there are multiple,
                # as that's how all the other errors work
                _raise_invalid(bad_val=j, outer_val=val, path=p, index=index)

            # Also check the child of val, as it will not be returned
            child = getattr(val, "children", None)
            if not isinstance(child, (tuple, MutableSequence)):
                if child and not _can_serialize(val):
                    _raise_invalid(
                        bad_val=child,
                        outer_val=val,
                        path=type(child).__name__,
                        index=index,
                    )

        if not _can_serialize(val):
            _raise_invalid(
                bad_val=val,
                outer_val=type(val).__name__,
                path="",
                index=index,