Group Results in WOQL

A how to guide to show you how to group query results using WOQL in TerminusDB and TerminusCMS

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

How to use group_by

If we need to group variables according to some criteria, we can create an aggregate of solutions using group_by.

A group by is composed of a focus, a template, and a group together with a query.

We will demonstrate this with the following query:

let v = Vars("person", "label", "eyes", "group");
limit(1)
.group_by(
  "eyes",
  ["label"],
  v.group,
  and(triple(v.person, "rdf:type", "@schema:People"),
      triple(v.person, "label", v.label),
      triple(v.person, "eye_color", v.eyes)))

The first argument, here "eyes" refers to the eyes variable, and is the variable around which to form the group, the focus.

The second ["label"] is the template, which refers to the variable "label". The template will be those things grouped under the first variable.

The third variable v.group, is the group variable, which will include groups of templates for each set of solutions which shares a focus.

This raw query output will be:

{
	"eyes": {
		"@type": "xsd:string",
		"@value": "black"
	},
	"group": [
		[{
			"@type": "xsd:string",
			"@value": "Greedo"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Nien Nunb"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Gasgano"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Kit Fisto"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Plo Koon"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Lama Su"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Taun We"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Shaak Ti"
		}],
		[{
			"@type": "xsd:string",
			"@value": "Tion Medon"
		}],
		[{
			"@type": "xsd:string",
			"@value": "BB8"
		}]
	],
	"label": null,
	"person": null
}