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Federation.java
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Federation.java
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package com.apollographql.federation.graphqljava;
import graphql.language.FieldDefinition;
import graphql.language.ObjectTypeDefinition;
import graphql.language.TypeDefinition;
import graphql.language.TypeName;
import graphql.schema.GraphQLSchema;
import graphql.schema.idl.RuntimeWiring;
import graphql.schema.idl.SchemaGenerator;
import graphql.schema.idl.SchemaParser;
import graphql.schema.idl.TypeDefinitionRegistry;
import graphql.schema.idl.TypeRuntimeWiring;
import org.jetbrains.annotations.NotNull;
import java.io.File;
import java.io.Reader;
import java.util.List;
import java.util.Optional;
public final class Federation {
private static final SchemaGenerator.Options generatorOptions = SchemaGenerator.Options.defaultOptions();
private Federation() {
}
@NotNull
public static SchemaTransformer transform(final GraphQLSchema schema) {
return new SchemaTransformer(schema, false);
}
// Note that GraphQLSchema does not support empty object types as of graphql-java v16. If you
// would like the query type to be empty, then add a dummy field to the query type in the given
// GraphQLSchema and pass queryTypeShouldBeEmpty as true. You can also use a transform()
// overload that accepts something other than a GraphQLSchema, as those overloads will
// automatically handle this for you. The output schema won't contain the dummy field, nor will
// it be visible to the gateway.
@NotNull
public static SchemaTransformer transform(final GraphQLSchema schema, final boolean queryTypeShouldBeEmpty) {
return new SchemaTransformer(schema, queryTypeShouldBeEmpty);
}
public static SchemaTransformer transform(final TypeDefinitionRegistry typeRegistry, final RuntimeWiring runtimeWiring) {
final boolean queryTypeShouldBeEmpty = ensureQueryTypeExists(typeRegistry);
RuntimeWiring newRuntimeWiring = ensureFederationDirectiveDefinitionsExist(typeRegistry, runtimeWiring);
final GraphQLSchema original = new SchemaGenerator().makeExecutableSchema(
generatorOptions,
typeRegistry,
newRuntimeWiring);
return transform(original, queryTypeShouldBeEmpty);
}
public static SchemaTransformer transform(final TypeDefinitionRegistry typeRegistry) {
return transform(typeRegistry, emptyWiring());
}
public static SchemaTransformer transform(final String sdl, final RuntimeWiring runtimeWiring) {
return transform(new SchemaParser().parse(sdl), runtimeWiring);
}
public static SchemaTransformer transform(final Reader sdl, final RuntimeWiring runtimeWiring) {
return transform(new SchemaParser().parse(sdl), runtimeWiring);
}
public static SchemaTransformer transform(final File sdl, final RuntimeWiring runtimeWiring) {
return transform(new SchemaParser().parse(sdl), runtimeWiring);
}
public static SchemaTransformer transform(final String sdl) {
return transform(sdl, emptyWiring());
}
public static SchemaTransformer transform(final Reader sdl) {
return transform(sdl, emptyWiring());
}
public static SchemaTransformer transform(final File sdl) {
return transform(sdl, emptyWiring());
}
private static RuntimeWiring emptyWiring() {
return RuntimeWiring.newRuntimeWiring().build();
}
// Returns true if a dummy field was added to the query type to ensure it's not empty.
private static boolean ensureQueryTypeExists(TypeDefinitionRegistry typeRegistry) {
final String queryName = typeRegistry.schemaDefinition()
.flatMap(sdef -> sdef.getOperationTypeDefinitions()
.stream()
.filter(op -> "query".equals(op.getName()))
.findFirst()
.map(def -> def.getTypeName().getName()))
.orElse("Query");
TypeDefinition<?> newQueryType = typeRegistry
.getType(queryName)
.orElse(ObjectTypeDefinition.newObjectTypeDefinition().name(queryName).build());
final boolean addDummyField = newQueryType instanceof ObjectTypeDefinition
&& ((ObjectTypeDefinition) newQueryType).getFieldDefinitions().isEmpty()
&& Optional.ofNullable(typeRegistry.objectTypeExtensions().get(queryName))
// Note that an object type extension must have at least one field
.map(List::isEmpty)
.orElse(true);
if (addDummyField) {
newQueryType = ((ObjectTypeDefinition) newQueryType).transform(objectTypeDefinitionBuilder ->
objectTypeDefinitionBuilder.fieldDefinition(FieldDefinition.newFieldDefinition()
.name("_dummy")
.type(new TypeName("String"))
.build()
)
);
}
// Note that TypeDefinitionRegistry will throw if you attempt to redefine a type, but it
// reacts fine if you try to remove a type that doesn't exist.
typeRegistry.remove(newQueryType);
typeRegistry.add(newQueryType);
return addDummyField;
}
private static RuntimeWiring ensureFederationDirectiveDefinitionsExist(
TypeDefinitionRegistry typeRegistry,
RuntimeWiring runtimeWiring
) {
// Add Federation directives if they don't exist.
FederationDirectives.allDefinitions
.stream()
.filter(def -> !typeRegistry.getDirectiveDefinition(def.getName()).isPresent())
.forEachOrdered(typeRegistry::add);
// Add scalar type for _FieldSet, since the directives depend on it.
if (!typeRegistry.getType(_FieldSet.typeName).isPresent()) {
typeRegistry.add(_FieldSet.definition);
}
// Also add the implementation for _FieldSet.
if (!runtimeWiring.getScalars().containsKey(_FieldSet.typeName)) {
return copyRuntimeWiring(runtimeWiring).scalar(_FieldSet.type).build();
} else {
return runtimeWiring;
}
}
private static RuntimeWiring.Builder copyRuntimeWiring(RuntimeWiring runtimeWiring) {
// Annoyingly graphql-java doesn't have a copy constructor for RuntimeWiring.Builder.
RuntimeWiring.Builder builder = RuntimeWiring.newRuntimeWiring();
runtimeWiring.getDataFetchers()
.entrySet()
.stream()
.map(entry -> {
String name = entry.getKey();
TypeRuntimeWiring.Builder typeWiring = TypeRuntimeWiring.newTypeWiring(name);
typeWiring.dataFetchers(entry.getValue());
if (runtimeWiring.getDefaultDataFetcherForType(name) != null) {
typeWiring.defaultDataFetcher(runtimeWiring.getDefaultDataFetcherForType(name));
}
if (runtimeWiring.getTypeResolvers().get(name) != null) {
typeWiring.typeResolver(runtimeWiring.getTypeResolvers().get(name));
}
if (runtimeWiring.getEnumValuesProviders().get(name) != null) {
typeWiring.enumValues(runtimeWiring.getEnumValuesProviders().get(name));
}
return typeWiring.build();
})
.forEach(builder::type);
if (runtimeWiring.getWiringFactory() != null) {
builder.wiringFactory(runtimeWiring.getWiringFactory());
}
if (runtimeWiring.getCodeRegistry() != null) {
builder.codeRegistry(runtimeWiring.getCodeRegistry());
}
runtimeWiring.getScalars().forEach((name, scalar) -> builder.scalar(scalar));
if (runtimeWiring.getFieldVisibility() != null) {
builder.fieldVisibility(runtimeWiring.getFieldVisibility());
}
runtimeWiring.getRegisteredDirectiveWiring().forEach(builder::directive);
runtimeWiring.getDirectiveWiring().forEach(builder::directiveWiring);
builder.comparatorRegistry(runtimeWiring.getComparatorRegistry());
runtimeWiring.getSchemaGeneratorPostProcessings().forEach(builder::transformer);
return builder;
}
}