Package graphql.analysis

Class QueryTraverser

java.lang.Object

graphql.analysis.QueryTraverser

@PublicApi
public class QueryTraverser
extends Object

Helps to traverse (or reduce) a Document (or parts of it) and tracks at the same time the corresponding Schema types.

This is an important distinction to just traversing the Document without any type information: Each field has a clearly defined type. See QueryVisitorFieldEnvironment.

Furthermore are the built in Directives skip/include automatically evaluated: if parts of the Document should be ignored they will not be visited. But this is not a full evaluation of a Query: every fragment will be visited/followed regardless of the type condition.

It also doesn't consider field merging, which means for example { user{firstName} user{firstName}} will result in four visitField calls.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	QueryTraverser.Builder

Field Summary

Fields

Modifier and Type	Field	Description
private CoercedVariables	coercedVariables
private final Map<String,FragmentDefinition>	fragmentsByName
private final GraphQLCompositeType	rootParentType
private final Collection<? extends Node>	roots
private final GraphQLSchema	schema

Constructor Summary

Constructors

Modifier	Constructor	Description
private	QueryTraverser(GraphQLSchema schema, Document document, String operation, CoercedVariables coercedVariables)
private	QueryTraverser(GraphQLSchema schema, Document document, String operation, RawVariables rawVariables)
private	QueryTraverser(GraphQLSchema schema, Node root, GraphQLCompositeType rootParentType, Map<String,FragmentDefinition> fragmentsByName, CoercedVariables coercedVariables)

Method Summary

Modifier and Type	Method	Description
private List<Node>	childrenOf(Node<?> node)
private GraphQLObjectType	getRootTypeFromOperation(OperationDefinition operationDefinition)
static QueryTraverser.Builder	newQueryTraverser()
<T> T	reducePostOrder(QueryReducer<T> queryReducer, T initialValue)	Reduces the fields of a Document (or parts of it) to a single value.
<T> T	reducePreOrder(QueryReducer<T> queryReducer, T initialValue)	Reduces the fields of a Document (or parts of it) to a single value.
Object	visitDepthFirst(QueryVisitor queryVisitor)
private Object	visitImpl(QueryVisitor visitFieldCallback, Boolean preOrder)
void	visitPostOrder(QueryVisitor visitor)	Visits the Document (or parts of it) in post-order.
void	visitPreOrder(QueryVisitor visitor)	Visits the Document (or parts of it) in pre-order.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

roots

private final Collection<? extends Node> roots

schema

private final GraphQLSchema schema

fragmentsByName

private final Map<String,FragmentDefinition> fragmentsByName

coercedVariables

private CoercedVariables coercedVariables

rootParentType

private final GraphQLCompositeType rootParentType

Constructor Details

QueryTraverser

private QueryTraverser(GraphQLSchema schema,
 Document document,
 String operation,
 CoercedVariables coercedVariables)

QueryTraverser

private QueryTraverser(GraphQLSchema schema,
 Document document,
 String operation,
 RawVariables rawVariables)

QueryTraverser

private QueryTraverser(GraphQLSchema schema,
 Node root,
 GraphQLCompositeType rootParentType,
 Map<String,FragmentDefinition> fragmentsByName,
 CoercedVariables coercedVariables)

Method Details

visitDepthFirst

public Object visitDepthFirst(QueryVisitor queryVisitor)

visitPostOrder

public void visitPostOrder(QueryVisitor visitor)

Visits the Document (or parts of it) in post-order.

Parameters:

visitor - the query visitor that will be called back

visitPreOrder

public void visitPreOrder(QueryVisitor visitor)

Visits the Document (or parts of it) in pre-order.

Parameters:

visitor - the query visitor that will be called back

reducePostOrder

public <T> T reducePostOrder(QueryReducer<T> queryReducer,
 T initialValue)

Reduces the fields of a Document (or parts of it) to a single value. The fields are visited in post-order.

Type Parameters:

T - the type of reduced value

Parameters:

queryReducer - the query reducer

initialValue - the initial value to pass to the reducer

Returns:

the calculated overall value

reducePreOrder

public <T> T reducePreOrder(QueryReducer<T> queryReducer,
 T initialValue)

Reduces the fields of a Document (or parts of it) to a single value. The fields are visited in pre-order.

Type Parameters:

T - the type of reduced value

Parameters:

queryReducer - the query reducer

initialValue - the initial value to pass to the reducer

Returns:

the calculated overall value

getRootTypeFromOperation

private GraphQLObjectType getRootTypeFromOperation(OperationDefinition operationDefinition)

childrenOf

private List<Node> childrenOf(Node<?> node)

visitImpl

private Object visitImpl(QueryVisitor visitFieldCallback,
 Boolean preOrder)

newQueryTraverser

public static QueryTraverser.Builder newQueryTraverser()