#3806: Properly apply NullValuePropertyMappingStrategy.IGNORE for collections / maps without setters

Signed-off-by: TangYang <tangyang9464@163.com>

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

@@ -240,6 +240,7 @@ public class CollectionAssignmentBuilder {
                 result,
                 method.getThrownTypes(),
                 targetType,
+                nvpms,
                 targetAccessorType.isFieldAssignment()
             );
         }

processor/src/main/java/org/mapstruct/ap/internal/model/assignment/GetterWrapperForCollectionsAndMaps.java

@@ -9,9 +9,12 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
+import org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem;
 import org.mapstruct.ap.internal.model.common.Assignment;
 import org.mapstruct.ap.internal.model.common.Type;
 
+import static org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem.IGNORE;
+
 /**
  * This wrapper handles the situation were an assignment must be done via a target getter method because there
  * is no setter available.
@@ -26,6 +29,14 @@ import org.mapstruct.ap.internal.model.common.Type;
  * @author Sjaak Derksen
  */
 public class GetterWrapperForCollectionsAndMaps extends WrapperForCollectionsAndMaps {
+    private final boolean ignoreMapNull;
+
+    public GetterWrapperForCollectionsAndMaps(Assignment decoratedAssignment,
+                                              List<Type> thrownTypesToExclude,
+                                              Type targetType,
+                                              boolean fieldAssignment) {
+        this( decoratedAssignment, thrownTypesToExclude, targetType, null, fieldAssignment );
+    }
 
     /**
      * @param decoratedAssignment source RHS
@@ -36,6 +47,7 @@ public class GetterWrapperForCollectionsAndMaps extends WrapperForCollectionsAnd
     public GetterWrapperForCollectionsAndMaps(Assignment decoratedAssignment,
                                               List<Type> thrownTypesToExclude,
                                               Type targetType,
+                                              NullValuePropertyMappingStrategyGem nvpms,
                                               boolean fieldAssignment) {
 
         super(
@@ -44,6 +56,7 @@ public class GetterWrapperForCollectionsAndMaps extends WrapperForCollectionsAnd
             targetType,
             fieldAssignment
         );
+        this.ignoreMapNull = nvpms == IGNORE;
     }
 
     @Override
@@ -54,4 +67,8 @@ public class GetterWrapperForCollectionsAndMaps extends WrapperForCollectionsAnd
         }
         return imported;
     }
+
+    public boolean isIgnoreMapNull() {
+        return ignoreMapNull;
+    }
 }

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

@@ -10,10 +10,13 @@
 <@lib.sourceLocalVarAssignment/>
 if ( ${ext.targetBeanName}.${ext.targetWriteAccessorName}<@lib.handleWriteAccesing /> != null ) {
     <@lib.handleExceptions>
-      <#if ext.existingInstanceMapping>
+      <#if ext.existingInstanceMapping && !ignoreMapNull>
         ${ext.targetBeanName}.${ext.targetWriteAccessorName}<@lib.handleWriteAccesing />.clear();
       </#if>
       <@lib.handleLocalVarNullCheck needs_explicit_local_var=false>
+        <#if ext.existingInstanceMapping && ignoreMapNull>
+            ${ext.targetBeanName}.${ext.targetWriteAccessorName}<@lib.handleWriteAccesing />.clear();
+        </#if>
         ${ext.targetBeanName}.${ext.targetWriteAccessorName}<@lib.handleWriteAccesing />.<#if ext.targetType.collectionType>addAll<#else>putAll</#if>( <@lib.handleWithAssignmentOrNullCheckVar/> );
       </@lib.handleLocalVarNullCheck>
     </@lib.handleExceptions>

processor/src/test/java/org/mapstruct/ap/test/bugs/_3806/Issue3806Mapper.java

@@ -0,0 +1,63 @@
+/*
+ * 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._3806;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.MappingTarget;
+import org.mapstruct.NullValuePropertyMappingStrategy;
+import org.mapstruct.factory.Mappers;
+
+@Mapper(nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE)
+public interface Issue3806Mapper {
+
+    Issue3806Mapper INSTANCE = Mappers.getMapper( Issue3806Mapper.class );
+
+    void update(@MappingTarget Target target, Target source);
+
+    class Target {
+
+        private final Collection<String> authors;
+        private final Map<String, String> booksByAuthor;
+
+        protected Collection<String> books;
+        protected Map<String, String> booksByPublisher;
+
+        public Target(Collection<String> authors, Map<String, String> booksByAuthor) {
+            this.authors = authors != null ? new ArrayList<>( authors ) : null;
+            this.booksByAuthor = booksByAuthor != null ? new HashMap<>( booksByAuthor ) : null;
+        }
+
+        public Collection<String> getAuthors() {
+            return authors;
+        }
+
+        public Map<String, String> getBooksByAuthor() {
+            return booksByAuthor;
+        }
+
+        public Collection<String> getBooks() {
+            return books;
+        }
+
+        public void setBooks(Collection<String> books) {
+            this.books = books;
+        }
+
+        public Map<String, String> getBooksByPublisher() {
+            return booksByPublisher;
+        }
+
+        public void setBooksByPublisher(Map<String, String> booksByPublisher) {
+            this.booksByPublisher = booksByPublisher;
+        }
+    }
+
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_3806/Issue3806Test.java

@@ -0,0 +1,86 @@
+/*
+ * 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._3806;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.entry;
+
+@WithClasses(Issue3806Mapper.class)
+@IssueKey("3806")
+class Issue3806Test {
+
+    @ProcessorTest
+    void shouldNotClearGetterOnlyCollectionsInUpdateMapping() {
+        Map<String, String> booksByAuthor = new HashMap<>();
+        booksByAuthor.put( "author1", "book1" );
+        booksByAuthor.put( "author2", "book2" );
+        List<String> authors = new ArrayList<>();
+        authors.add( "author1" );
+        authors.add( "author2" );
+
+        List<String> books = new ArrayList<>();
+        books.add( "book1" );
+        books.add( "book2" );
+        Map<String, String> booksByPublisher = new HashMap<>();
+        booksByPublisher.put( "publisher1", "book1" );
+        booksByPublisher.put( "publisher2", "book2" );
+        Issue3806Mapper.Target target = new Issue3806Mapper.Target( authors, booksByAuthor );
+        target.setBooks( books );
+        target.setBooksByPublisher( booksByPublisher );
+
+        Issue3806Mapper.Target source = new Issue3806Mapper.Target( null, null );
+        Issue3806Mapper.INSTANCE.update( target, source );
+
+        assertThat( target.getAuthors() ).containsExactly( "author1", "author2" );
+        assertThat( target.getBooksByAuthor() )
+            .containsOnly(
+                entry( "author1", "book1" ),
+                entry( "author2", "book2" )
+            );
+
+        assertThat( target.getBooks() ).containsExactly( "book1", "book2" );
+        assertThat( target.getBooksByPublisher() )
+            .containsOnly(
+                entry( "publisher1", "book1" ),
+                entry( "publisher2", "book2" )
+            );
+
+        booksByAuthor = new HashMap<>();
+        booksByAuthor.put( "author3", "book3" );
+        authors = new ArrayList<>();
+        authors.add( "author3" );
+
+        books = new ArrayList<>();
+        books.add( "book3" );
+        booksByPublisher = new HashMap<>();
+        booksByPublisher.put( "publisher3", "book3" );
+        source = new Issue3806Mapper.Target( authors, booksByAuthor );
+        source.setBooks( books );
+        source.setBooksByPublisher( booksByPublisher );
+        Issue3806Mapper.INSTANCE.update( target, source );
+
+        assertThat( target.getAuthors() ).containsExactly( "author3" );
+        assertThat( target.getBooksByAuthor() )
+            .containsOnly(
+                entry( "author3", "book3" )
+            );
+
+        assertThat( target.getBooks() ).containsExactly( "book3" );
+        assertThat( target.getBooksByPublisher() )
+            .containsOnly(
+                entry( "publisher3", "book3" )
+            );
+    }
+}