Model mapper Converter failed to convert Object to java.lang.Integer with java.lang.NullPointerException - spring-boot

Question

perhaps someone can give me an insite. Ok i have Purchase Entity with nested Transaction set of Entities. What i'm trying to do is convert additional DTO property Integer paymentStatus using custom method but getting NullPointerException for ModelMapper Converter
#Data
#NoArgsConstructor
#AllArgsConstructor
#Builder
#Entity
#Table(name = "purchase")
public class Purchase {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "purchase_id", nullable = false)
private Integer purchaseId;
#Column(name = "purchase_total_cost")
private Double purchaseTotalCost;
#Column(name = "purchase_company_id", nullable = false)
private Integer purchaseCompanyId;
#Column(name = "purchase_user_id", nullable = false)
private Integer purchaseUserId;
#Column(name = "purchase_stock_id", nullable = false)
private Integer purchaseStockId;
#Column(name = "purchase_supplier_contact_id")
private Integer purchaseSupplierContactId;
#Column(name = "purchase_supplier_id")
private Integer purchaseSupplierId;
#Column(name = "purchase_inventory_id")
private Integer purchaseInventoryId;
#Column(name = "purchase_date")
private LocalDateTime purchaseDate;
#Column(name = "date_created")
#CreationTimestamp
public LocalDateTime dateCreated;
#Column(name = "date_updated")
#UpdateTimestamp
public LocalDateTime dateUpdated;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne
#JoinColumn(name = "purchase_user_id", referencedColumnName = "user_id", insertable = false, updatable = false)
private User purchaseUser;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne
#JoinColumn(name = "purchase_stock_id", referencedColumnName = "stock_id", insertable = false, updatable = false)
private Stock purchaseStock;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne
#JoinColumn(name = "purchase_supplier_id", referencedColumnName = "supplier_id", insertable = false, updatable = false)
private Supplier purchaseSupplier;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "purchase_supplier_contact_id", referencedColumnName = "contact_id", insertable = false, updatable = false)
private SupplierContact purchaseSupplierContact;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne
#JoinColumn(name = "purchase_company_id", referencedColumnName = "company_id", insertable = false, updatable = false)
private Company purchaseCompany;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#ManyToOne
#JoinColumn(name = "purchase_inventory_id", referencedColumnName = "inventory_id", insertable = false, updatable = false)
private Inventory purchaseInventory;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#OneToMany(fetch = FetchType.LAZY,
mappedBy = "costLogPurchase")
#Cascade({org.hibernate.annotations.CascadeType.MERGE,
org.hibernate.annotations.CascadeType.DELETE,
org.hibernate.annotations.CascadeType.REMOVE
})
private Set<CostLog> purchaseCostLogs;
#ToString.Exclude
#EqualsAndHashCode.Exclude
#OneToMany(fetch = FetchType.LAZY,
cascade = CascadeType.ALL,
mappedBy = "ingredientPurchase")
private Set<PurchaseHasIngredient> purchaseIngredients;
// #ToString.Exclude
#EqualsAndHashCode.Exclude
#OneToMany(fetch = FetchType.EAGER,
cascade = CascadeType.ALL,
mappedBy = "transactionPurchase")
private Set<Transaction> purchaseTransactions;
#Data
#NoArgsConstructor
#AllArgsConstructor
#Builder
#Entity
#Table(name = "transaction")
public class Transaction {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "transaction_id", nullable = false)
private Integer transactionId;
#Column(name = "transaction_status")
private Byte transactionStatus;
#Column(name = "transaction_amount", nullable = false)
private Double transactionAmount;
#Column(name = "transaction_code", length = 100)
private String transactionCode;
#Column(name = "transaction_payment_point_id")
private Integer transactionPaymentPointId;
#Column(name = "transaction_user_id")
private Integer transactionUserId;
#Column(name = "transaction_order_id")
private Integer transactionOrderId;
#Column(name = "transaction_purchase_id")
private Integer transactionPurchaseId;
#Column(name = "transaction_date")
public LocalDateTime transactionDate;
#Column(name = "date_created")
#CreationTimestamp
public LocalDateTime dateCreated;
#Column(name = "date_updated")
#UpdateTimestamp
public LocalDateTime dateUpdated;
#EqualsAndHashCode.Exclude
#ToString.Exclude
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "transaction_payment_point_id", referencedColumnName = "payment_point_id", insertable = false, updatable = false)
private PaymentPoint transactionPaymentPoint;
#EqualsAndHashCode.Exclude
#ToString.Exclude
#ManyToOne
#JoinColumn(name = "transaction_user_id", referencedColumnName = "user_id", insertable = false, updatable = false)
private User transactionUser;
#EqualsAndHashCode.Exclude
#ToString.Exclude
#ManyToOne
#Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
#JoinColumn(name = "transaction_order_id", referencedColumnName = "order_id", insertable = false, updatable = false)
private Order transactionOrder;
#EqualsAndHashCode.Exclude
#ToString.Exclude
#ManyToOne(fetch = FetchType.EAGER)
#Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
#JoinColumn(name = "transaction_purchase_id", referencedColumnName = "purchase_id", insertable = false, updatable = false)
private Purchase transactionPurchase;
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class TransactionDTO implements Serializable {
private static final long serialVersionUID = 1L;
private Integer transactionId;
private Byte transactionStatus;
private Double transactionAmount;
private String transactionCode;
private Integer transactionPaymentPointId;
private String transactionPaymentPointName;
private Integer transactionUserId;
private String transactionUserName;
private Integer transactionOrderId;
private Integer transactionPurchaseId;
public LocalDateTime transactionDate;
public LocalDateTime dateCreated;
public LocalDateTime dateUpdated;
}
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class PurchaseDTO {
private static final long serialVersionUID = 1L;
private Integer purchaseId;
private Integer purchaseUserId;
private String purchaseUserName;
private Integer purchaseCompanyId;
private Integer purchaseStockId;
private String purchaseStockName;
private Integer purchaseSupplierId;
private String purchaseSupplierName;
private Integer paymentStatus; // this is additional property
private Integer purchaseInventoryId;
private Double purchaseTotalCost;
private Integer purchaseSupplierContactId;
private LocalDateTime purchaseDate;
private LocalDateTime dateCreated;
private LocalDateTime dateUpdated;
private Set<PurchaseHasIngredientDTO> purchaseIngredients;
private Set<TransactionDTO> purchaseTransactions;
#Configuration
public class ModelMapperConfig {
#Bean
public ModelMapper modelMapper() {
ModelMapper mapper = new ModelMapper();
mapper.getConfiguration().setPreferNestedProperties(false)
.setSkipNullEnabled(true)
.setMatchingStrategy(MatchingStrategies.STANDARD);
mapper.createTypeMap(Purchase.class, PurchaseDTO.class)
.addMappings(purchaseDTOPropertyMapUsingPaymentStatusConverter);
return mapper;
}
PropertyMap<Purchase, PurchaseDTO> purchaseDTOPropertyMapUsingPaymentStatusConverter = new PropertyMap<>() {
#Override
protected void configure() {
using(ctx->mapSpecificFields(source.getPurchaseTransactions(), source.getPurchaseTotalCost())).
map(source, destination.getPaymentStatus());
}
};
public Integer mapSpecificFields(Set<Transaction> set, Double total) {
int b;
if(set==null){
b = 0;
}
double result = 0;
for(Transaction transaction: set) {
double sum = transaction.getTransactionAmount();
sum++;
result = sum/total;
}
if(result==0){
b=0;
}else if (result==1){
b=2;
}else{
b=1;
}
return b;
}
}
#Service
public class PurchaseService extends EntityMapperService<PurchaseDTO, Purchase> implements EntityService<Purchase> {
#PersistenceContext
private EntityManager entityManager;
private final PurchaseRepository repository;
private final PurchaseHasIngredientRepository purchaseIngredientsRepository;
private final ModelMapper mapper;
#Override
public PurchaseDTO toDto(Purchase entity) {
return Objects.isNull(entity)
? null
: mapper.map(entity, PurchaseDTO.class);
}
}
test set up
#SpringBootTest
class PurchaseServiceTest {
#Autowired
private ModelMapper mapper;
#Autowired
private PurchaseService service;
Transaction t1;
Transaction t2;
Set<Transaction> transactions;
TransactionDTO td1;
TransactionDTO td2;
Set<TransactionDTO> transactionDTOS;
Purchase purchase;
PurchaseDTO dto;
#BeforeEach
void setUp() {
t1 = Transaction.builder()
.transactionId(11)
.transactionAmount(12.00)
.transactionPurchaseId(1)
.build();
t2 = Transaction.builder()
.transactionId(12)
.transactionAmount(10.00)
.transactionPurchaseId(1)
.build();
transactions = Sets.newHashSet(t1,t2);
td1 = TransactionDTO.builder()
.transactionPurchaseId(1)
.transactionId(11)
.transactionAmount(12.00)
.build();
td2 = TransactionDTO.builder()
.transactionId(12)
.transactionPurchaseId(1)
.transactionAmount(10.00)
.build();
transactionDTOS = Sets.newHashSet(td1,td2);
purchase = Purchase.builder()
.purchaseId(1)
.purchaseCompanyId(2)
.purchaseUserId(3)
.purchaseStockId(4)
.purchaseTransactions(transactions)
.purchaseTotalCost(22.00)
.build();
dto = PurchaseDTO.builder()
.purchaseId(1)
.purchaseUserId(3)
.purchaseCompanyId(2)
.purchaseStockId(4)
.paymentStatus(0)
.purchaseTotalCost(22.00)
.purchaseTransactions(transactionDTOS)
.build();
}
#DisplayName("JUnit test for toDto method for <Purchase, PurchaseDTO> typemap using paymentStatus converter")
#Test
void toDtoUsingConverterForPurchaseTypeMap() {
PurchaseDTO testedDto = service.toDto(purchase);
assertThat(testedDto).isEqualTo(dto);
}
}
stack trace of error
org.modelmapper.MappingException: ModelMapper mapping errors:
1) Converter com.hrc.hrcweb.ModelMapperConfig$1$$Lambda$1240/0x00000008013e8ea0#5f5efbfc failed to convert com.hrc.hrcweb.entities.Purchase to java.lang.Integer.
1 error
at org.modelmapper.internal.Errors.throwMappingExceptionIfErrorsExist(Errors.java:380)
at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:80)
at org.modelmapper.ModelMapper.mapInternal(ModelMapper.java:573)
at org.modelmapper.ModelMapper.map(ModelMapper.java:406)
at com.hrc.hrcweb.servises.PurchaseService.toDto(PurchaseService.java:139)
at com.hrc.hrcweb.servises.PurchaseService$$FastClassBySpringCGLIB$$ffc82405.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
at org.springframework.aop.framework.CglibAopProxy.invokeMethod(CglibAopProxy.java:386)
at org.springframework.aop.framework.CglibAopProxy.access$000(CglibAopProxy.java:85)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:704)
at com.hrc.hrcweb.servises.PurchaseService$$EnhancerBySpringCGLIB$$485f630d.toDto(<generated>)
at com.hrc.hrcweb.servises.PurchaseServiceTest.toDtoUsingConverterForPurchaseTypeMap(PurchaseServiceTest.java:93)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:69)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
Caused by: java.lang.NullPointerException: Cannot invoke "com.hrc.hrcweb.entities.Purchase.getPurchaseTransactions()" because "this.source" is null
at com.hrc.hrcweb.ModelMapperConfig$1.lambda$configure$0(ModelMapperConfig.java:68)
at org.modelmapper.internal.MappingEngineImpl.convert(MappingEngineImpl.java:306)
at org.modelmapper.internal.MappingEngineImpl.setDestinationValue(MappingEngineImpl.java:243)
at org.modelmapper.internal.MappingEngineImpl.propertyMap(MappingEngineImpl.java:187)
at org.modelmapper.internal.MappingEngineImpl.typeMap(MappingEngineImpl.java:151)
at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:105)
at org.modelmapper.internal.MappingEngineImpl.map(MappingEngineImpl.java:71)
... 77 more
What am i doing wrong?

Answer 1

After meny hours, i couldn't find any solution to map additional properties or map some expressions to perform some custom calculations for DTO objects properties using model mapper, i had to switch to Mapstuct for these kind of operations, it has some nice custom mapping of target property to expression=java(anymethod) and u can use any method to map target, it's very convenient. example perhaps someone will find this information usefull.
I solved everything with this piece of code
#Mapping(target = "paymentStatus", expression = "java(getPaymentStatus(purchase))")
PurchaseDTO toDto(Purchase purchase);
and this custom method calculating status
default Integer getPaymentStatus(Purchase purchase){
Integer status;
if(purchase.getPurchaseTransactions()==null){
status = 0;
}
double result = 0;
double sum = 0;
double total = purchase.getPurchaseTotalCost();
for(Transaction transaction: purchase.getPurchaseTransactions()) {
sum += transaction.getTransactionAmount();
result = sum/total;
}
if(result==0){
status=0;
}else if (result==1){
status=2;
}else{
status=1;
}
return status;
}