#1997 Use builders to construct empty objects in update wrapper

processor/src/main/java/org/mapstruct/ap/internal/model/MethodReference.java

@@ -6,6 +6,7 @@
 package org.mapstruct.ap.internal.model;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedHashSet;
@@ -58,8 +59,10 @@ public class MethodReference extends ModelElement implements Assignment {
     private final Type definingType;
     private final List<ParameterBinding> parameterBindings;
     private final Parameter providingParameter;
+    private final List<MethodReference> methodsToChain;
     private final boolean isStatic;
     private final boolean isConstructor;
+    private final boolean isMethodChaining;
 
     /**
      * Creates a new reference to the given method.
@@ -95,6 +98,8 @@ public class MethodReference extends ModelElement implements Assignment {
         this.isStatic = method.isStatic();
         this.name = method.getName();
         this.isConstructor = false;
+        this.methodsToChain = Collections.emptyList();
+        this.isMethodChaining = false;
    }
 
     private MethodReference(BuiltInMethod method, ConversionContext contextParam) {
@@ -111,6 +116,8 @@ public class MethodReference extends ModelElement implements Assignment {
         this.isStatic = method.isStatic();
         this.name = method.getName();
         this.isConstructor = false;
+        this.methodsToChain = Collections.emptyList();
+        this.isMethodChaining = false;
     }
 
     private MethodReference(String name, Type definingType, boolean isStatic) {
@@ -127,6 +134,8 @@ public class MethodReference extends ModelElement implements Assignment {
         this.providingParameter = null;
         this.isStatic = isStatic;
         this.isConstructor = false;
+        this.methodsToChain = Collections.emptyList();
+        this.isMethodChaining = false;
     }
 
     private MethodReference(Type definingType, List<ParameterBinding> parameterBindings) {
@@ -142,6 +151,8 @@ public class MethodReference extends ModelElement implements Assignment {
         this.providingParameter = null;
         this.isStatic = false;
         this.isConstructor = true;
+        this.methodsToChain = Collections.emptyList();
+        this.isMethodChaining = false;
 
         if ( parameterBindings.isEmpty() ) {
             this.importTypes = Collections.emptySet();
@@ -159,6 +170,24 @@ public class MethodReference extends ModelElement implements Assignment {
         }
     }
 
+    private MethodReference(MethodReference... references) {
+        this.name = null;
+        this.definingType = null;
+        this.sourceParameters = Collections.emptyList();
+        this.returnType = null;
+        this.declaringMapper = null;
+        this.importTypes = Collections.emptySet();
+        this.thrownTypes = Collections.emptyList();
+        this.isUpdateMethod = false;
+        this.contextParam = null;
+        this.parameterBindings = null;
+        this.providingParameter = null;
+        this.isStatic = false;
+        this.isConstructor = false;
+        this.methodsToChain = Arrays.asList( references );
+        this.isMethodChaining = true;
+    }
+
     public MapperReference getDeclaringMapper() {
         return declaringMapper;
     }
@@ -267,6 +296,12 @@ public class MethodReference extends ModelElement implements Assignment {
         if ( isStatic() ) {
             imported.add( definingType );
         }
+        if ( isMethodChaining() ) {
+            for ( MethodReference methodToChain : methodsToChain ) {
+                imported.addAll( methodToChain.getImportTypes() );
+            }
+        }
+
         return imported;
     }
 
@@ -276,6 +311,12 @@ public class MethodReference extends ModelElement implements Assignment {
         if ( assignment != null ) {
             exceptions.addAll( assignment.getThrownTypes() );
         }
+        if ( isMethodChaining() ) {
+            for ( MethodReference methodToChain : methodsToChain ) {
+                exceptions.addAll( methodToChain.getThrownTypes() );
+            }
+
+        }
         return exceptions;
     }
 
@@ -311,6 +352,14 @@ public class MethodReference extends ModelElement implements Assignment {
         return isConstructor;
     }
 
+    public boolean isMethodChaining() {
+        return isMethodChaining;
+    }
+
+    public List<MethodReference> getMethodsToChain() {
+        return methodsToChain;
+    }
+
     public List<ParameterBinding> getParameterBindings() {
         return parameterBindings;
     }
@@ -385,6 +434,10 @@ public class MethodReference extends ModelElement implements Assignment {
         return new MethodReference( type, parameterBindings );
     }
 
+    public static MethodReference forMethodChaining(MethodReference... references) {
+        return new MethodReference( references );
+    }
+
     @Override
     public String toString() {
         String mapper = declaringMapper != null ? declaringMapper.getType().getName() : "";

processor/src/main/java/org/mapstruct/ap/internal/model/ObjectFactoryMethodResolver.java

@@ -139,6 +139,10 @@ public class ObjectFactoryMethodResolver {
     }
 
     public static MethodReference getBuilderFactoryMethod(Method method, BuilderType builder ) {
+        return getBuilderFactoryMethod( method.getReturnType(), builder );
+    }
+
+    public static MethodReference getBuilderFactoryMethod(Type typeToBuild, BuilderType builder ) {
         if ( builder == null ) {
             return null;
         }
@@ -149,7 +153,7 @@ public class ObjectFactoryMethodResolver {
             return null;
         }
 
-        if ( !builder.getBuildingType().isAssignableTo( method.getReturnType() ) ) {
+        if ( !builder.getBuildingType().isAssignableTo( typeToBuild ) ) {
             //TODO print error message
             return null;
         }

processor/src/main/java/org/mapstruct/ap/internal/model/PropertyMapping.java

@@ -419,6 +419,28 @@ public class PropertyMapping extends ModelElement {
 
                 Assignment factory = ObjectFactoryMethodResolver
                     .getFactoryMethod( method, targetType, SelectionParameters.forSourceRHS( rightHandSide ), ctx );
+
+                if ( factory == null && targetBuilderType != null) {
+                    // If there is no dedicated factory method and the target has a builder we will try to use that
+                    MethodReference builderFactoryMethod = ObjectFactoryMethodResolver.getBuilderFactoryMethod(
+                        targetType,
+                        targetBuilderType
+                    );
+
+                    if ( builderFactoryMethod != null ) {
+
+                        MethodReference finisherMethod = BuilderFinisherMethodResolver.getBuilderFinisherMethod(
+                            method,
+                            targetBuilderType,
+                            ctx
+                        );
+
+                        if ( finisherMethod != null ) {
+                            factory = MethodReference.forMethodChaining( builderFactoryMethod, finisherMethod );
+                        }
+                    }
+
+                }
                 return new UpdateWrapper(
                     rhs,
                     method.getThrownTypes(),

processor/src/main/resources/org/mapstruct/ap/internal/model/MethodReference.ftl

@@ -18,6 +18,8 @@
         <@includeModel object=definingType/>.<@methodCall/>
     <#elseif constructor>
         new <@includeModel object=definingType/><#if (parameterBindings?size > 0)>( <@arguments/> )<#else>()</#if>
+    <#elseif methodChaining>
+        <#list methodsToChain as methodToChain><@includeModel object=methodToChain /><#if methodToChain_has_next>.</#if></#list>
     <#else>
         <@methodCall/>
     </#if>

processor/src/test/java/org/mapstruct/ap/test/bugs/_1997/Car.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._1997;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class Car {
+    private String model;
+
+    private Car(Builder builder) {
+        this.model = builder.model;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+
+        private String model;
+
+        public Builder model(String model) {
+            this.model = model;
+            return this;
+        }
+
+        public Car build() {
+            return new Car( this );
+        }
+
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1997/CarDetail.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._1997;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class CarDetail {
+    private String model;
+
+    private CarDetail(Builder builder) {
+        this.model = builder.model;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+
+        private String model;
+
+        public Builder model(String model) {
+            this.model = model;
+            return this;
+        }
+
+        public CarDetail build() {
+            return new CarDetail( this );
+        }
+
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1997/CarInsurance.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._1997;
+
+/**
+ * @author Filip Hrisafov
+ */
+public class CarInsurance {
+    private CarDetail detail;
+
+    private CarInsurance(Builder builder) {
+        this.detail = builder.detail;
+    }
+
+    public CarDetail getDetail() {
+        return detail;
+    }
+
+    public void setDetail(CarDetail detail) {
+        this.detail = detail;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+
+        private CarDetail detail;
+
+        public Builder detail(CarDetail detail) {
+            this.detail = detail;
+            return this;
+        }
+
+        public CarInsurance build() {
+            return new CarInsurance( this );
+        }
+
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1997/CarInsuranceMapper.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._1997;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.MappingTarget;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Filip Hrisafov
+ */
+@Mapper
+public interface CarInsuranceMapper {
+
+    CarInsuranceMapper INSTANCE = Mappers.getMapper( CarInsuranceMapper.class );
+
+    @Mapping(source = "model", target = "detail.model")
+    void update(Car source, @MappingTarget CarInsurance target);
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_1997/Issue1997Test.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._1997;
+
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Filip Hrisafov
+ */
+@WithClasses({
+    Car.class,
+    CarDetail.class,
+    CarInsurance.class,
+    CarInsuranceMapper.class
+})
+class Issue1997Test {
+
+    @ProcessorTest
+    void shouldCorrectCreateIntermediateObjectsWithBuilder() {
+        Car source = Car.builder().model( "Model S" ).build();
+        CarInsurance target = CarInsurance.builder().build();
+        assertThat( target.getDetail() ).isNull();
+
+        CarInsuranceMapper.INSTANCE.update( source, target );
+
+        assertThat( target.getDetail() ).isNotNull();
+        assertThat( target.getDetail().getModel() ).isEqualTo( "Model S" );
+    }
+}