Hi,
For your scenario, I would use the below filter condition in the Post body of the JSON data source.
> \{
>
> "$filter":"(taxid_list).taxid=1"
> \}
As of now, it is only possible to pass the JSON document(i.e., Array vaule ) using $filter parameter, not as a value of the field.
For more information, you can have look at [Parameters of the Web Service RESTful and REST Web Services](https://community.denodo.com/docs/html/browse/latest/vdp/administration/restful_architecture/restful_web_service/input_parameters_of_the_restful_web_service) and [Restrictions of the JSON syntax](https://community.denodo.com/docs/html/browse/latest/vdp/administration/restful_architecture/restful_web_service/requests_with_input_compound_values) section of the Virtual DataPort Administration Guide.
Hope this helps!