isNull method
You can invoke this method to add a query condition in which a field in an entity class is null.
Implementation
void isNull(String field) {
if (field.isEmpty) {
throw FormatException('field cannot be an empty string.', field);
}
_queryElements.add(
<String, dynamic>{
_QueryConstants.FIELD: field,
_QueryConstants.OPERATION: _QueryConstants.IS_NULL,
},
);
}