GraphQL Reference

GraphQL queries are composed of:
  • Queries
  • Fields
  • Arguments
Each Class in TerminusDB automatically generates a top-level Query. Each property of the class automatically generates both arguments and fields.
The names of the types of arguments and fields are generated automatically subject to name mapping.
In turn, each property which is an edge leading to a new object of a class will have its own field with arguments.
Each concrete data query will be terminal and will generate a specific field parameter for search.

Example

For example, using the following TerminusDB schema:
{ "@type" : "Class",
"@id" : "Person",
"name" : "xsd:string",
"dob" : "xsd:dateTime",
"friend" : {"@type" : "Set", "@class" : "Person" }}
TerminusDB will generate the following GraphQL class.
type Query {
Person(
id: ID
"""skip N elements"""
offset: Int
"""limit results to N elements"""
limit: Int
filter: Person_Filter
"""order by the given fields"""
orderBy: Person_Ordering
): [Person!]!
}
type Person {
dob: DateTime!
friend(
id: ID
"""skip N elements"""
offset: Int
"""limit results to N elements"""
limit: Int
filter: Person_Filter
"""order by the given fields"""
orderBy: Person_Ordering
): [Person!]!
name: String!
id: ID!
}
The Person query, allows you to query for a person at the top level, along with a number of arguments, including: a filter (for search), a limit for reducing to a defined length of results, an offset, for obtaining results starting from some offset (for use in paging) and an orderBy to obtain the results in a defined order.
In addition, we have the various fields of a Person object, each of which may have arguments if they are objects or simple data types for terminal fields.
One can use such a query by using the GraphQL endpoint.

Arguments

Arguments are restrictions or meta-fields about the query. These can be used to limit results, or filter to specific results, as well as perform ordering.

id

The id of an object can be directly supplied, in order to ensure that we only obtain the specific object of interest.
A person might be retrieved by supplying the id as a variable in the following way:
query Person(id:$id){
name
}

offset

GraphQL will retrieve all objects in the database for a given class type, unless offset and limit are supplied. offset will start a query from a given result offset, allowing the query user to page results.
query Person(limit: 3 offset: 3){
name
Person(
id: ID
"""skip N elements"""
offset: Int
"""limit results to N elements"""
limit: Int
filter: Person_Filter
"""order by the given fields"""
orderBy: Person_Ordering
): [Person!]!
}
This query retrieves the second page of a 3-object page of persons.

limit

GraphQL will retrieve all objects in the database for a given class type, unless offset and limit are supplied. limit will only find the limit-number of results, allowing the query user to page results.
query Person(limit: 3 offset: 3){
name
}
This query retrieves the second page of a 3-object page of persons.

orderBy

The orderBy filter allows the user to order results according to some data in the object. For instance, to create an ordering on people, we might write:
query Person(limit: 3 offset: 3, orderBy: { dob: DESC, name: ASC}){
name
dob
}
This will yield Persons from youngest to oldest, ordering by name in the event of a "tie" on date of birth.

filter

Filters allow you to restrict to specific results by reducing the set to those objects which match the filter fields.
Each filter is an input object, defined for the specific class and generated automatically by TerminusDB. The Person object defined above gets the input objects:
input Person_Filter {
dob: DateTimeFilterInputObject
friend: Person_Collection_Filter
name: StringFilterInputObject
_and: [Person_Filter!]
_or: [Person_Filter!]
_not: Person_Filter
}
input Person_Collection_Filter {
someHave: Person_Filter
allHave: Person_Filter
}
input StringFilterInputObject {
eq: String
ne: String
lt: String
le: String
gt: String
ge: String
regex: String
startsWith: String
allOfTerms: [String!]
anyOfTerms: [String!]
}
input DateTimeFilterInputObject {
eq: DateTime
ne: DateTime
lt: DateTime
le: DateTime
gt: DateTime
ge: DateTime
}
Filters can apply to immediate values, such as the dob (date of birth), which can be restricted using a time comparison, or they can be filters on linked objects, such as the Person_Collection_Filter which allows us to compare with our friends.
In GraphQL we might write a simple query over people as:
query Person(orderBy: { name: ASC},
filter: { name: {regex: "(Joe|Joseph)"},
_and: [{friend:
{someHave:
{name: {regex: "(Jim|James)"}}}}]}){
name
dob
}
This finds name and date of birth of all people who have a name which contains "Joe" or "Joesph" and who are friends with someone named "Jim" or "James", in order of ascending name.

Filter Builtin Types

Filters have to work with all of the GraphQL base types, along with the extensions which TerminusDB currently supports (DateTime, and BigInt).

BigIntFilterInputObject

Big integers use the widely available BigInt type extension to GraphQL.
The Filters available for BigInt are:
  • eq: Equality
  • ne: disequality
  • lt: Less than
  • le: Less than or equal
  • gt: Greater than
  • ge: Greater than or equal
When a field of an object refers to a BigInt, we can filter it by writing a query along the following lines:
query {
Event(filter : { years_since_big_bang : { ge : "8000000000"}}){
event_name
years_since_big_bang
}
}

DateTimeFilterInputObject

Date time objects use the widely available DateTime type extension to GraphQL.
The Filters available for BigInt are:
  • eq: Equality
  • ne: disequality
  • lt: Less than
  • le: Less than or equal
  • gt: Greater than
  • ge: Greater than or equal
query {
Event(filter : { date_of_event : { ge : "2000-01-01T00:00:00Z"}}){
event_name
date_of_event
}
}

StringFilterInputObject

Strings are native GraphQL types. TerminusDB exposes the following filter options for strings:
  • eq: Equality
  • ne: Disequality
  • lt: Less than
  • le: Less than or equal
  • gt: Greater than
  • ge: Greater than or equal
  • regex: Matches regex
  • startsWith: Matches the string prefix
  • allOfTerms: Contains all terms in the list of terms
  • anyOfTerms: Contains any of the terms in the list of terms
A query filter using strings could be written as follows:
query {
Event(filter : { event_name : { regex : "[Cc]elstial [Ee]vent"}}){
event_name
}
}

BooleanFilterInputObject

Booleans are native GraphQL types. TerminusDB exposes the following filter options:
  • eq: Equality
  • ne: Disequality
A query filter using booleans could be written as follows:
query {
Event(filter : { is_super_nova : { eq : true}}){
event_name
}
}

SmallIntegerFilterInputObject

Integers (signed, 32-bit integers) are native GraphQL types. TerminusDB exposes the following filter options:
  • eq: Equality
  • ne: disequality
  • lt: Less than
  • le: Less than or equal
  • gt: Greater than
  • ge: Greater than or equal
A query filter using booleans could be written as follows:
query {
Civilization(filter : { kardashev_scale : { ge : 3}}){
name
kardashev_scale
}
}

_and

The _and filter combinator allows us to chain constraints. It takes two filter objects relevant at the current level.
We can find all civilizations of a high Kardashev scale using a query such as:
query {
Civilization(filter : {_and : [{ kardashev_scale : { le : 5}}
{ kardashev_scale : { ge : 3}}]){
name
kardashev_scale
}
}

_or

The _or filter combinator allows us to make choices of constraints. It takes two filter objects relevant at the current level. It is implicitly combined as if with _and, with any filters at the current level.
We can find all civilizations of a high Kardashev scale, which is also a galactic civilisation using a query such as:
query {
Civilization(filter : { galactic_scale : {eq : true},
_or : [{ kardashev_scale : { eq : 2}}
{ kardashev_scale : { eq : 3}}]){
name
kardashev_scale
}
}

_not

The _not operator allows us to combine other constraints with dis-constraints, which remove any elements which match its sub-filter.
We can ask for galactic civilizations which have not mastered energy acquisition at level 3 on the Kardashev scale.
query {
Civilization(filter : { galactic_scale : {eq : true},
_not : { kardashev_scale : { eq : 3}}}){
name
kardashev_scale
}
}