Class Query

tinydb/queries.py:130–514

TinyDB Queries. Allows building queries for TinyDB databases. There are two main ways of using queries: 1) ORM-like usage: >>> User = Query() >>> db.search(User.name == 'John Doe') >>> db.search(User['logged-in'] == True) 2) Classical usage: >>> db.search(wh

class Query(QueryInstance):
    """
    TinyDB Queries.

    Allows building queries for TinyDB databases. There are two main ways of
    using queries:

    1) ORM-like usage:

    >>> User = Query()
    >>> db.search(User.name == 'John Doe')
    >>> db.search(User['logged-in'] == True)

    2) Classical usage:

    >>> db.search(where('value') == True)

    Note that ``where(...)`` is a shorthand for ``Query(...)`` allowing for
    a more fluent syntax.

    Besides the methods documented here you can combine queries using the
    binary AND and OR operators:

    >>> # Binary AND:
    >>> db.search((where('field1').exists()) & (where('field2') == 5))
    >>> # Binary OR:
    >>> db.search((where('field1').exists()) | (where('field2') == 5))

    Queries are executed by calling the resulting object. They expect to get
    the document to test as the first argument and return ``True`` or
    ``False`` depending on whether the documents match the query or not.
    """

    def __init__(self) -> None:
        # The current path of fields to access when evaluating the object
        self._path: Tuple[Union[str, Callable], ...] = ()

        # Prevent empty queries to be evaluated
        def notest(_):
            raise RuntimeError('Empty query was evaluated')

        super().__init__(
            test=notest,
            hashval=(None,)
        )

    def __repr__(self):
        return '{}()'.format(type(self).__name__)

    def __hash__(self):
        return super().__hash__()

    def __getattr__(self, item: str):
        # Generate a new query object with the new query path
        # We use type(self) to get the class of the current query in case
        # someone uses a subclass of ``Query``
        query = type(self)()