Add support for returning optional results

spring-data-mock-sample-jpa/src/main/java/com/mmnaseri/utils/samples/spring/data/jpa/repository/MembershipRepository.java

@@ -6,6 +6,7 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 
 import java.util.List;
+import java.util.Optional;
 
 /**
  * @author Milad Naseri ([email protected])
@@ -17,7 +18,7 @@ public interface MembershipRepository extends JpaRepository<Membership, String>
 
   List<Membership> findByGroup(Group group);
 
-  Membership findByUserAndGroup(User user, Group group);
+  Optional<Membership> findByUserAndGroup(User user, Group group);
 
   List<Membership> findAllByUserAndActive(User user, boolean active);
 }

spring-data-mock-sample-jpa/src/main/java/com/mmnaseri/utils/samples/spring/data/jpa/service/impl/DefaultGroupService.java

@@ -9,6 +9,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
 import static java.util.stream.Collectors.toList;
 
@@ -43,7 +44,7 @@ public void deleteGroup(Group group) {
 
   @Override
   public void join(Group group, User user) {
-    if (membershipRepository.findByUserAndGroup(user, group) != null) {
+    if (membershipRepository.findByUserAndGroup(user, group).isPresent()) {
       return;
     }
     final Membership membership = new Membership();
@@ -54,11 +55,11 @@ public void join(Group group, User user) {
 
   @Override
   public void leave(Group group, User user) {
-    final Membership membership = membershipRepository.findByUserAndGroup(user, group);
-    if (membership == null) {
+    final Optional<Membership> membership = membershipRepository.findByUserAndGroup(user, group);
+    if (!membership.isPresent()) {
       return;
     }
-    membershipRepository.delete(membership);
+    membershipRepository.delete(membership.get());
   }
 
   @Override
@@ -83,10 +84,11 @@ public List<Group> groups(User user) {
 
   @Override
   public void deactivate(final Group group, final User user) {
-    Membership membership = membershipRepository.findByUserAndGroup(user, group);
-    if (membership == null) {
+    Optional<Membership> optional = membershipRepository.findByUserAndGroup(user, group);
+    if (!optional.isPresent()) {
       return;
     }
+    Membership membership = optional.get();
     membership.setActive(false);
     membershipRepository.save(membership);
   }

spring-data-mock/src/main/java/com/mmnaseri/utils/spring/data/proxy/impl/DefaultResultAdapterContext.java

@@ -17,6 +17,7 @@
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.NullToListenableFutureResultAdapter;
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.NullToSliceResultAdapter;
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.NumberIterableResultAdapter;
+import com.mmnaseri.utils.spring.data.proxy.impl.adapters.OptionalResultAdapter;
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.PageIterableResultAdapter;
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.SameTypeResultAdapter;
 import com.mmnaseri.utils.spring.data.proxy.impl.adapters.SimpleIterableResultAdapter;
@@ -66,6 +67,7 @@ public DefaultResultAdapterContext(boolean registerDefaults) {
       adapters.add(new NullToListenableFutureResultAdapter());
       adapters.add(new NumberIterableResultAdapter());
       adapters.add(new SimpleIterableResultAdapter());
+      adapters.add(new OptionalResultAdapter());
       adapters.add(new IteratorIterableResultAdapter());
       adapters.add(new CollectionIterableResultAdapter());
       adapters.add(new SliceIterableResultAdapter());

spring-data-mock/src/main/java/com/mmnaseri/utils/spring/data/proxy/impl/adapters/OptionalResultAdapter.java

@@ -0,0 +1,52 @@
+package com.mmnaseri.utils.spring.data.proxy.impl.adapters;
+
+import com.mmnaseri.utils.spring.data.domain.Invocation;
+import com.mmnaseri.utils.spring.data.error.ResultAdapterFailureException;
+
+import java.util.Iterator;
+import java.util.Optional;
+
+/**
+ * This adapter accepts all invocations wherein the original value is an {@link Iterable} object and
+ * the requested method type is an {@link Optional} value.
+ *
+ * <p>While adapting, the adapter will also check that the iterable yields only one item and that it
+ * is of the same type or of a child type of the type requested by the invoked method.
+ *
+ * <p>This adapter runs at the priority {@literal -400}.
+ *
+ * @author Milad Naseri ([email protected])
+ * @since 2.1.1 (10/29/2020)
+ */
+public class OptionalResultAdapter extends AbstractIterableResultAdapter<Object> {
+
+  public OptionalResultAdapter() {
+    super(-400);
+  }
+
+  @Override
+  public boolean accepts(final Invocation invocation, final Object originalValue) {
+    if (!(originalValue instanceof Iterable)) {
+      return false;
+    }
+    final Class<?> returnType = invocation.getMethod().getReturnType();
+    return returnType.isAssignableFrom(Optional.class);
+  }
+
+  @Override
+  protected Object doAdapt(final Invocation invocation, final Iterable iterable) {
+    final Iterator iterator = iterable.iterator();
+    if (iterator.hasNext()) {
+      final Object value = iterator.next();
+      if (iterator.hasNext()) {
+        throw new ResultAdapterFailureException(
+            iterable,
+            invocation.getMethod().getReturnType(),
+            "Expected only one item but found many");
+      }
+      return Optional.of(value);
+    } else {
+      return Optional.empty();
+    }
+  }
+}

spring-data-mock/src/main/java/com/mmnaseri/utils/spring/data/proxy/impl/adapters/SimpleIterableResultAdapter.java

@@ -5,12 +5,13 @@
 import com.mmnaseri.utils.spring.data.tools.PropertyUtils;
 
 import java.util.Iterator;
+import java.util.Optional;
 import java.util.concurrent.Future;
 
 /**
  * This adapter accepts all invocations wherein the original value is an {@link Iterable} object and
  * the requested method type is a simple value. Simple types are types that are not a subtype of
- * {@link Iterable}, {@link Iterator}, or {@link Future}.
+ * {@link Iterable}, {@link Iterator}, {@link Future}, or {@link Optional}.
  *
  * <p>While adapting, the adapter will also check that the iterable yields only one item and that it
  * is of the same type or of a child type of the type requested by the invoked method.
@@ -34,7 +35,8 @@ public boolean accepts(Invocation invocation, Object originalValue) {
     final Class<?> returnType = invocation.getMethod().getReturnType();
     return !Iterable.class.isAssignableFrom(returnType)
         && !Iterator.class.isAssignableFrom(returnType)
-        && !Future.class.isAssignableFrom(returnType);
+        && !Future.class.isAssignableFrom(returnType)
+        && !Optional.class.isAssignableFrom(returnType);
   }
 
   @Override