Writing a filter in WOQL

To use this HowTo, first clone the Star Wars demo into your team on TerminusCMS. You will then have access to the data needed for this tutorial.

Since WOQL is a datalog, filters are just part of the query. You can express negative information, or constraints on the variables in order to get a restriction down to the things you want.

For instance, we can write the following query in the query panel for the Star Wars demo:

let v = Vars("person","person_name","vehicle","vehicle_name");
limit(10)
.select(v.person_name, v.vehicle_name)
  .and(triple(v.vehicle, "pilot", v.person),
       triple(v.vehicle, "label", v.vehicle_name),
       triple(v.person, "label", v.person_name))

This results in:

[ {"person_name": {"@type":"xsd:string", "@value":"Chewbacca"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Han Solo"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Lando Calrissian"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Nien Nunb"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Luke Skywalker"},
   "vehicle_name": {"@type":"xsd:string", "@value":"X-wing"}},
  {"person_name": {"@type":"xsd:string", "@value":"Wedge Antilles"},
   "vehicle_name": {"@type":"xsd:string", "@value":"X-wing"}},
  {"person_name": {"@type":"xsd:string", "@value":"Jek Tono Porkins"},
   "vehicle_name": {"@type":"xsd:string", "@value":"X-wing"}},
  {"person_name": {"@type":"xsd:string", "@value":"Biggs Darklighter"},
   "vehicle_name": {"@type":"xsd:string", "@value":"X-wing"}},
  {"person_name": {"@type":"xsd:string", "@value":"Darth Vader"},
   "vehicle_name": {"@type":"xsd:string", "@value":"TIE Advanced x1"}},
  {"person_name": {"@type":"xsd:string", "@value":"Boba Fett"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Slave 1"}}
]

We can ask for a specific example of a vehicle name by filtering on equality.

For instance:

let v = Vars("person","person_name","vehicle","vehicle_name");
select(v.person_name, v.vehicle_name)
  .and(triple(v.vehicle, "pilot", v.person),
       triple(v.vehicle, "label", v.vehicle_name),
       triple(v.person, "label", v.person_name),
       eq(v.vehicle_name, string("Millennium Falcon")))

Which results in:

[ {"person_name": {"@type":"xsd:string", "@value":"Chewbacca"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Han Solo"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Lando Calrissian"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}},
  {"person_name": {"@type":"xsd:string", "@value":"Nien Nunb"},
   "vehicle_name": {"@type":"xsd:string", "@value":"Millennium Falcon"}}
]

We can also write:

let v = Vars("person","person_name","vehicle","vehicle_name");
select(v.person_name, v.vehicle_name)
  .and(triple(v.vehicle, "pilot", v.person),
       triple(v.vehicle, "label", v.vehicle_name),
       triple(v.person, "label", v.person_name),
       not(eq(v.vehicle_name, string("Millennium Falcon"))))

In which we get the complement of the above.

Or, we can use the regex operator to get a wider variety, for instance:

let v = Vars("person","person_name","vehicle","vehicle_name","pattern");
select(v.person_name, v.vehicle_name)
  .and(triple(v.vehicle, "pilot", v.person),
       triple(v.vehicle, "label", v.vehicle_name),
       triple(v.person, "label", v.person_name),
       regex("W.*", v.vehicle_name, [v.pattern]))

In this case, we get the following back in JSON format:

[ {"person_name": {"@type":"xsd:string", "@value":"Darth Vader"},
   "vehicle_name": {"@type":"xsd:string", "@value":"TIE Advanced x1"}},
  {"person_name": {"@type":"xsd:string", "@value":"Arvel Crynyd"},
   "vehicle_name": {"@type":"xsd:string", "@value":"A-wing"}},
  {"person_name": {"@type":"xsd:string", "@value":"Chewbacca"},
   "vehicle_name": {"@type":"xsd:string", "@value":"AT-ST"}}
]