add support for java.util.Optional

Author: koenpunt

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/GraphQlArgumentInstantiator.java

@@ -77,7 +77,7 @@ public <T> T instantiate(Class<T> targetType, Map<String, Object> arguments) {
 					if (methodParam.getParameterType() == OptionalInput.class) {
 						args[i] = propertyValues.contains(paramName) ? OptionalInput.defined(null) : OptionalInput.undefined();
 					} else if(methodParam.isOptional()) {
-						args[i] = (methodParam.getParameterType() == Optional.class ? Optional.empty() : null);
+						args[i] = (methodParam.getParameterType() == Optional.class && propertyValues.contains(paramName) ? Optional.empty() : null);
 					}
 				}
 				else {

spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/OptionalInputArgumentConversionService.java

@@ -4,6 +4,9 @@
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.graphql.data.method.OptionalInput;
 
+import javax.swing.text.html.Option;
+import java.util.Optional;
+
 public class OptionalInputArgumentConversionService implements ConversionService {
     @Override
     public boolean canConvert(Class<?> sourceType, Class<?> targetType) {
@@ -12,7 +15,7 @@ public boolean canConvert(Class<?> sourceType, Class<?> targetType) {
 
     @Override
     public boolean canConvert(TypeDescriptor sourceType, TypeDescriptor targetType) {
-        return targetType.getType() == OptionalInput.class;
+        return targetType.getType() == OptionalInput.class || targetType.getType() == Optional.class;
     }
 
     @Override
@@ -22,6 +25,10 @@ public <T> T convert(Object source, Class<T> targetType) {
 
     @Override
     public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
-        return OptionalInput.defined(source);
+        if (targetType.getType() == Optional.class) {
+            return Optional.of(source);
+        } else {
+            return OptionalInput.defined(source);
+        }
     }
 }

spring-graphql/src/test/java/org/springframework/graphql/data/method/annotation/support/ArgumentMethodArgumentResolverTests.java

@@ -20,6 +20,7 @@
 import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.core.type.TypeReference;
@@ -38,6 +39,8 @@
 import org.springframework.stereotype.Controller;
 import org.springframework.util.ClassUtils;
 
+import javax.annotation.Nullable;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
@@ -85,7 +88,7 @@ void shouldResolveJavaBeanArgument() throws Exception {
 		assertThat(result).isNotNull().isInstanceOf(BookInput.class);
 		assertThat((BookInput) result).hasFieldOrPropertyWithValue("name", "test name")
 				.hasFieldOrPropertyWithValue("authorId", 42L)
-				.hasFieldOrPropertyWithValue("notes", OptionalInput.undefined());
+				.hasFieldOrPropertyWithValue("notes", null);
 	}
 
 	@Test
@@ -99,7 +102,7 @@ void shouldResolveJavaBeanOptionalArgument() throws Exception {
 		assertThat((BookInput) result)
 				.hasFieldOrPropertyWithValue("name", "test name")
 				.hasFieldOrPropertyWithValue("authorId", 42L)
-				.hasFieldOrPropertyWithValue("notes", OptionalInput.defined("Hello"));
+				.hasFieldOrPropertyWithValue("notes", Optional.of("Hello"));
 	}
 
 	@Test
@@ -113,7 +116,7 @@ void shouldResolveJavaBeanOptionalNullArgument() throws Exception {
 		assertThat((BookInput) result)
 				.hasFieldOrPropertyWithValue("name", "test name")
 				.hasFieldOrPropertyWithValue("authorId", 42L)
-				.hasFieldOrPropertyWithValue("notes", OptionalInput.defined(null));
+				.hasFieldOrPropertyWithValue("notes", Optional.empty());
 	}
 
 	@Test
@@ -232,7 +235,8 @@ static class BookInput {
 
 		Long authorId;
 
-		OptionalInput<String> notes = OptionalInput.undefined();
+		@Nullable
+		Optional<String> notes = null;
 
 		public String getName() {
 			return this.name;
@@ -250,12 +254,14 @@ public void setAuthorId(Long authorId) {
 			this.authorId = authorId;
 		}
 
-		public OptionalInput<String> getNotes() {
+		@Nullable
+		public Optional<String> getNotes() {
 			return this.notes;
 		}
 
-		public void setNotes(OptionalInput<String> notes) {
-			this.notes = (notes == null) ? OptionalInput.defined(null) : notes;
+
+		public void setNotes(@Nullable Optional<String> notes) {
+			this.notes = notes;
 		}
 	}