def __init__(self, sort=None, logic=None, weight=None, simple=None, simple_weight=None, extract_as=None,<EOL>extract_all=None, extract_when_missing=None, length=None, offset=None, filter=None, **kwargs):
super(ChemicalFieldQuery, self).__init__(<EOL>sort=sort, weight=weight, logic=logic, simple=simple, simple_weight=simple_weight, extract_as=extract_as,<EOL>extract_all=extract_all, extract_when_missing=extract_when_missing, length=length, offset=offset, **kwargs)<EOL>self._filter = None<EOL>self.filter = filter<EOL>
Constructor.

:param sort: ASCENDING or DESCENDING to set the sort order on this field.
:param logic: Logic for this query. Must be equal to one of "MUST", "MUST_NOT", "SHOULD", or "OPTIONAL".
:param weight: Weight for the query.
:param simple: String with the simple search to run against all fields.
:param simple_weight: Dictionary of relative paths to their weights for simple queries.
:param extract_as: String with the alias to save this field under.
:param extract_all: Boolean setting whether all values in an array should be extracted.
:param extract_when_missing: Any valid JSON-supported object or PIF object. This value is returned when a value is missing that should be extracted (and the overall query is still satisfied).
:param length: One or more :class:`FieldOperation` objects against the length field.
:param offset: One or more :class:`FieldOperation` objects against the offset field.
:param filter: One or more :class:`ChemicalFilter` objects against this field.