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DQL Query Language

DQL (Dgraph Query Language) is the primary query language for OWLGraph. It supports graph traversals, filtering, aggregation, and OWLGraph’s ontology-aware extensions.

Basic Query

{
  q(func: type(Animal)) {
    name
    dgraph.type
  }
}

Root Functions

Function	Description
`type(X)`	Nodes with type X (subsumption-aware)
`exactType(X)`	Nodes with explicitly asserted type X
`eq(pred, val)`	Equality match
`has(pred)`	Nodes with the predicate
`allofterms(pred, "words")`	Full-text term match
`anyofterms(pred, "words")`	Any term match
`regexp(pred, /pattern/)`	Regex match
`uid(0x1, 0x2)`	Specific UIDs

Filters

{
  q(func: type(Book)) @filter(eq(testament, "Old") AND has(reference)) {
    name
    reference
  }
}

Operators: AND, OR, NOT, eq, ge, le, gt, lt, has, type

Pagination and Ordering

{
  q(func: type(Person), first: 10, offset: 20, orderasc: name) {
    name
  }
}

Aggregation

{
  q(func: type(Prophecy)) {
    count(uid)
    min(val(publicationYear))
    max(val(publicationYear))
  }
}

Nested Traversals

{
  q(func: type(Prophecy)) {
    reference
    text
    hasTheme { name }
    fulfilledBy {
      reference
      inBook { name testament }
    }
  }
}

OWLGraph Extensions

Transitive Property Paths

Follow a transitive property:

# Unbounded: follow until no more edges
{
  q(func: eq(name, "San Francisco")) {
    name
    locatedIn* { name }
  }
}

# Bounded: maximum N hops
{
  q(func: eq(name, "San Francisco")) {
    name
    locatedIn*2 { name }
  }
}

{
  q(func: type(Dog)) {
    name
    dgraph.type @facets(owl.inferred)
  }
}

Variables

{
  var(func: type(Author)) {
    books as authorOf {
      themes as hasTheme
    }
  }

  q(func: uid(themes), orderdesc: val(count)) {
    name
    appearances: val(count)
  }
}

Mutations in DQL

{
  set {
    _:new <dgraph.type> "Dog" .
    _:new <name> "Rex" .
  }
}

For full DQL syntax, see the Dgraph DQL documentation.