sub / sub!
The sub keyword is used in TypeQL to specify a parent type for a subtype.
For specifying only a direct subtype in a pattern, with no type inference,
use the sub! keyword instead.
Syntax
The syntax of a sub or sub! statement includes:
-
Subject — a subtype
-
Predicate — the
sub/sub!keyword -
Object — a parent type
<subtype> sub <parent-type>;Behavior
TypeQL statements with the sub keyword can be used in any kind of query.
The sub keyword adds a constraint for subject to be a type that is a subtype of the object:
-
In schema queries — the
subandsub!keywords don’t have any difference. -
In data queries — the
subandsub!keywords are used to match either all existing subtypes or only direct subtypes of a given type respectively.
Usage in a schema definition
For this example, use a database with the IAM schema and sample data loaded.
Since in Define and Undefine queries you can’t use variables,
both subject and object can only be type labels in a schema statement.
So a statement with the sub keyword is used to define (declare) one type (preceding subject) as a subtype
of another type (succeeding object).
For example, to define a new type pdf as a subtype of an existing file type, use:
define
pdf sub file;Usage in a match pattern
For this example, use a database with the IAM schema and sample data loaded.
In a data query pattern a sub statement can be used only in a match clause or condition of a rule.
Both subject and object of a sub statement can be concept variables, or one of them can be a type label.
The sub keyword adds a constraint on a subject being an exact type, a direct subtype,
or indirect subtype (via type inference) of the type used as an object.
For example, to match all subtypes of a subject entity type, use:
match
$subtype sub subject;
fetch
$subtype;See example output
{ "type": { "label": "user", "root": "entity" } }
{ "type": { "label": "business-unit", "root": "entity" } }
{ "type": { "label": "user-role", "root": "entity" } }
{ "type": { "label": "user-account", "root": "entity" } }
{ "type": { "label": "person", "root": "entity" } }
{ "type": { "label": "user-group", "root": "entity" } }
{ "type": { "label": "subject", "root": "entity" } }match
$type sub! subject;
fetch $type;See example output
{ "type": { "label": "user", "root": "entity" } }
{ "type": { "label": "user-group", "root": "entity" } }