Schema Queries with WOQL

What you'll achieve By the end of this guide, you will know how to query and inspect your schema using WOQL.

Prerequisites: TerminusDB running on localhost:6363 with the Star Wars dataset cloned. If you haven't done this yet, follow the Explore a Real Dataset tutorial (Steps 1–2), or run:
curl -u admin:root -X POST http://localhost:6363/api/clone/admin/star-wars \
  -H "Content-Type: application/json" \
  -H "Authorization-Remote: Basic cHVibGljOnB1YmxpYw==" \
  -d '{"remote_url": "https://data.terminusdb.org/public/star-wars", "label": "Star Wars", "comment": "Star Wars dataset"}'

Finding elements from the schema.

In order to query the schema, you can use graph arguments to WOQL. TerminusDB stores each branch as a pair of graphs, an instance graph and a schema graph.

We can specify the graph by passing it as an argument to the quad word.

To find all classes in the schema we can write:

Example: JavaScript

let v = Vars("cls");
quad(v.cls, "rdf:type", "sys:Class", "schema")

This results in:

cls
@schema:Film
@schema:People
@schema:Planet
@schema:Species
@schema:Starship
@schema:Vehicle

The @schema denotes the default schema prefix, and makes it clear that this identifier lives in the schema name space rather than the data name space.

We can also use the typical triple word if we use from to set our default graph to schema instead of instance.

Example: JavaScript

let v = Vars("cls");
from("schema")
  .triple(v.cls, "rdf:type", "sys:Class")

Finding elements from the schema.

Was this helpful?