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mapstruct#1699 add sensible defaults to NullValuePropertyMapping.SET_TO_DEFAULT (mapstruct#1702)
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6 files changed

Lines changed: 41 additions & 9 deletions

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‎core/src/main/java/org/mapstruct/NullValuePropertyMappingStrategy.java‎

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@@ -33,6 +33,17 @@ public enum NullValuePropertyMappingStrategy {
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/**
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* If a source bean property equals {@code null} the target bean property will be set to its default value.
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* <p>
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* This means:
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* <ol>
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* <li>For {@code List} MapStruct generates an {@code ArrayList}</li>
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* <li>For {@code Map} a {@code HashMap}</li>
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* <li>For arrays an empty array</li>
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* <li>For {@code String} {@code ""}</li>
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* <li>for primitive / boxed types a representation of {@code 0} or {@code false}</li>
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* <li>For all other objects an new instance is created, requiring an empty constructor.</li>
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* </ol>
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* <p>
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* Make sure that a {@link Mapping#defaultValue()} is defined if no empty constructor is available on
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* the default value.
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*/

‎documentation/src/main/asciidoc/mapstruct-reference-guide.asciidoc‎

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@@ -2134,11 +2134,15 @@ The strategy works in a hierarchical fashion. Setting `nullValueMappingStrategy`
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[[mapping-result-for-null-properties]]
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=== Controlling mapping result for 'null' properties in bean mappings (update mapping methods only).
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MapStruct offers control over the property to set in an `@MappingTarget` annotated target bean when the source property equals `null` or the presence check method yields absent.
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MapStruct offers control over the property to set in an `@MappingTarget` annotated target bean when the source property equals `null` or the presence check method results in 'absent'.
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By default the source property will be set to null. However:
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By default the target property will be set to null.
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1. By specifying `nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.SET_TO_DEFAULT` on `@Mapping`, `@BeanMapping`, `@Mapper` or `@MappingConfig`, the mapping result can be altered to return *default* values. Please note that a default constructor is required. If not available, use the `@Mapping#defaultValue`. For `List` MapStruct generates an `ArrayList`, for `Map` mapstruct generates a `HashMap`.
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However:
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1. By specifying `nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.SET_TO_DEFAULT` on `@Mapping`, `@BeanMapping`, `@Mapper` or `@MappingConfig`, the mapping result can be altered to return *default* values.
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For `List` MapStruct generates an `ArrayList`, for `Map` a `HashMap`, for arrays an empty array, for `String` `""` and for primitive / boxed types a representation of `false` or `0`.
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For all other objects an new instance is created. Please note that a default constructor is required. If not available, use the `@Mapping#defaultValue`.
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2. By specifying `nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.IGNORE` on `@Mapping`, `@BeanMapping`, `@Mapper` or `@MappingConfig`, the mapping result will be equal to the original value of the `@MappingTarget` annotated target.
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‎processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java‎

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@@ -934,6 +934,22 @@ public String getNull() {
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throw new UnsupportedOperationException( getName() );
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}
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public String getSensibleDefault() {
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if ( isPrimitive() ) {
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return getNull();
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}
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else if ( "String".equals( getName() ) ) {
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return "\"\"";
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}
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else {
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if ( isNative() ) {
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// must be boxed, since primitive is already checked
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return typeFactory.getType( typeUtils.unboxedType( typeMirror ) ).getNull();
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}
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}
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return null;
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}
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@Override
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public int hashCode() {
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// javadoc typemirror: "Types should be compared using the utility methods in Types. There is no guarantee

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

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@@ -161,6 +161,8 @@ Performs a default assignment with a default value.
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new <@includeModel object=ext.targetType.implementationType/>()
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<#elseif ext.targetType.arrayType>
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new <@includeModel object=ext.targetType.componentType/>[0]
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<#elseif ext.targetType.sensibleDefault??>
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${ext.targetType.sensibleDefault}
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<#else>
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new <@includeModel object=ext.targetType/>()
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</#if>

‎processor/src/test/java/org/mapstruct/ap/test/bugs/_1685/UserMapper.java‎

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@@ -38,7 +38,6 @@ public interface UserMapper {
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@InheritInverseConfiguration
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@BeanMapping( nullValuePropertyMappingStrategy = NullValuePropertyMappingStrategy.SET_TO_DEFAULT )
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@Mapping( target = "phone", source = "contactDataDTO.phone", defaultValue = "0" )
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void updateUserFromUserAndDefaultDTO(UserDTO userDTO, @MappingTarget User user);
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}

‎processor/src/test/resources/fixtures/org/mapstruct/ap/test/bugs/_1685/UserMapperImpl.java‎

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@@ -12,8 +12,8 @@
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@Generated(
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value = "org.mapstruct.ap.MappingProcessor",
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date = "2019-01-27T12:40:32+0100",
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comments = "version: , compiler: Eclipse JDT (Batch) 1.2.100.v20160418-1457, environment: Java 1.8.0_181 (Oracle Corporation)"
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date = "2019-01-28T21:17:39+0100",
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comments = "version: , compiler: javac, environment: Java 1.8.0_181 (Oracle Corporation)"
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)
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public class UserMapperImpl implements UserMapper {
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@@ -116,7 +116,7 @@ public void updateUserFromUserAndDefaultDTO(UserDTO userDTO, User user) {
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user.setAddress( address );
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}
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else {
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user.setAddress( new String() );
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user.setAddress( "" );
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}
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String phone = userDTOContactDataDTOPhone( userDTO );
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if ( phone != null ) {
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user.setEmail( email );
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}
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else {
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user.setEmail( new String() );
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user.setEmail( "" );
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}
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if ( userDTO.getName() != null ) {
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user.setName( userDTO.getName() );
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}
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else {
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user.setName( new String() );
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user.setName( "" );
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}
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}
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