Language

Learn about the Hot Chocolate v16 GraphQL Abstract Syntax Tree (AST) and syntax node types.

Abstract Syntax Tree (AST)

Hot Chocolate parses every incoming GraphQL request into an abstract syntax tree (AST). Each node in this tree represents a part of the incoming GraphQL query. The type system (ObjectType, InputType, etc.) configures the schema, and the AST represents parsed queries and schema documents.

GraphQL

query Users {
  userName
  address {
    street
    nr
  }
}

graph TD;
    OperationDefinitionNode   -->  s1["SelectionSetNode"]
    s1["SelectionSetNode"]  --> id5["FieldNode (userName)"]
    s1["SelectionSetNode"]  --> id1["FieldNode (address)"]
    id1["FieldNode (address)"] -->  s2["SelectionSetNode"]
    s2["SelectionSetNode"]  -->   id3["FieldNode (street)"]
    s2["SelectionSetNode"]  -->   id4["FieldNode (nr)"]

Syntax Node

Every node in the syntax tree implements ISyntaxNode.

The ToString method of a syntax node prints the corresponding GraphQL syntax.

The interface defines the NodeKind of the node.

Node Kinds:

Name	Description (Spec Link)	Context	Example
Name	All names, e.g., Field, Argument	Both	foo
NamedType	Reference to a type	Both	Foo
ListType	Definition of a list	Both	[Foo]
NonNullType	Definition of a non-null type	Both	Foo!
Argument	An argument with a Name and Value	Both	foo: "bar"
Directive	A directive	Query	@foo
Document	A complete file or request	Query (out)
OperationDefinition	A query, mutation, or subscription operation	Query (out)	query Foo {}
VariableDefinition	Variables defined by an operation	Query (out)	($foo: String)
Variable	A variable	Query (out)	$foo
SelectionSet	A set of Field, FragmentSpread, or InlineFragment selections	Query (out)	{foo bar}
Field	A field in a selection set	Query (out)	foo
FragmentSpread	A spread of a FragmentDefinition	Query (out)	...f1
InlineFragment	An inline fragment	Query (out)	... on Foo { bar}
FragmentDefinition	A fragment definition	Query (out)	fragment f1 on Foo {}
IntValue	An int value	Query (in)	1
StringValue	A string value	Query (in)	"bar"
BooleanValue	A boolean value	Query (in)	true
NullValue	A null value	Query (in)	null
EnumValue	An enum value	Query (in)	FOO
FloatValue	A float value	Query (in)	0.2
ListValue	A list value	Query (in)	["string"]
ObjectValue	An object value	Query (in)	{foo: "bar" }
ObjectField	A field of an input object type	Query (in)	foo: "bar"
SchemaDefinition	Schema definition	Schema	schema {}
OperationTypeDefinition	Root operation type definition	Schema	query:FooQuery
ScalarTypeDefinition	Scalar definition	Schema	scalar JSON
ObjectTypeDefinition	Object type definition	Schema	type Foo{}
FieldDefinition	Field definition	Schema	bar:String
InputValueDefinition	Input value definition	Schema	x: Float
InterfaceTypeDefinition	Interface definition	Schema	interface NamedEntity {}
UnionTypeDefinition	Union definition	Schema	union Ex = Foo \| Bar
EnumTypeDefinition	Enum definition	Schema	enum Foo {BAR}
EnumValueDefinition	Enum value definition	Schema	BAR
InputObjectTypeDefinition	Input type definition	Schema	input FooInput {}
SchemaExtension	Schema extension	Schema	extend schema {}
ScalarTypeExtension	Scalar extension	Schema	extend scalar Foo @bar
ObjectTypeExtension	Object type extension	Schema	extend type Foo { name}
InterfaceTypeExtension	Interface type extension	Schema	extend interface NamedEntity {}
UnionTypeExtension	Union type extension	Schema	extend union Ex = Foo{}
EnumTypeExtension	Enum type extension	Schema	extend enum foo{}
InputObjectTypeExtension	Input type extension	Schema	input foo {}
DirectiveDefinition	Directive definition	Schema	directive @foo on

Next Steps

Visitors for traversing the AST
Extending filtering for building custom filter logic from AST nodes

Last updated on April 13, 2026 by Michael Staib