Let's say I have an entity Products that has an int number field:
#Entity
#Table(name = "products")
public class Product {
#Id
#GeneratedValue(generator = "inc")
#GenericGenerator(name = "inc", strategy = "increment")
private int id;
private int number;
public int getId() {
return id;
}
void setId(int id) {
this.id = id;
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
}
And there is a repository extending JpaRepository:
#Repository
interface SqlProductRepository extends JpaRepository<Product, Integer> {
Optional<List<Product>> findProductsByNumberIs0(); //compile error
}
Here is the error I get when I start the app:
nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlProductRepository' defined in com.example.demo.adapter.SqlProductRepository defined in #EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Invocation of init method failed; nested exception is org.springframework.data.repository.query.QueryCreationException: Could not create query for public abstract java.util.Optional com.example.demo.product.ProductRepository.findProductsByNumberIs0()! Reason: Failed to create query for method public abstract java.util.Optional com.example.demo.product.ProductRepository.findProductsByNumberIs0()! No property numberIs0 found for type Product!; nested exception is java.lang.IllegalArgumentException: Failed to create query for method public abstract java.util.Optional com.example.demo.product.ProductRepository.findProductsByNumberIs0()! No property numberIs0 found for type Product!
What can I do to get a list of products that has number field equal to 0 ?
This is not supported by query derivation, so you have to put in a little more work. The simplest variant is to provide a JPQL query in an annotation.
#Repository
interface SqlProductRepository extends JpaRepository<Product, Integer> {
#Query("select p from Product p where number = 0")
List<Product> someMethodName();
}
I removed the Optional wrapper since List already has a perfect representation of nothing: The empty list.
Try a slight variation on your method name and signature. You should be able to define your repository like this:
#Repository
interface SqlProductRepository extends JpaRepository<Product, Integer> {
List<Product> findProductsByNumber(int number);
}
And then if you want those products where number == 0, then you can call your repository's method, passing in 0 as the argument:
List<Product> products = sqlProductRepository.findProductsByNumber(0);
This also allows you the flexibility to call findProductsByNumber() with any arbitrary number for any other use case.
EDIT: the repository's method should return a List, but if no products matching your criteria are found, you will just end up with an empty list.
Related
I have an entity:
import javax.persistence.Convert;
#Entity(name = "my_entity")
public class MyEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#Convert(converter = StringListConverter.class)
private List<String> emails;
// next fields omitted...
}
Converter which is used by emails field in entity (typical implementation like LocalDateTimeConverter):
import javax.persistence.Converter;
#Converter
public class StringListConverter implements AttributeConverter<List<String>, String> {
private static final String SPLIT_CHAR = ";";
#Override
public String convertToDatabaseColumn(List<String> stringList) {
if (CollectionUtils.isNotEmpty(stringList)) {
return String.join(SPLIT_CHAR, stringList);
} else {
return null;
}
}
#Override
public List<String> convertToEntityAttribute(String string) {
if (StringUtils.isNotBlank(string)) {
return Arrays.asList(string.split(SPLIT_CHAR));
} else {
return Collections.emptyList();
}
}
}
(I store emails separated by semicolons in one column. StringListConverter do that conversion.)
And Spring Data repository:
import org.springframework.data.domain.Example;
public interface MyRepository extends JpaRepository<MyEntity, Long> {
default List<MyEntity> findMatchingMyEntity(MyEntity myEntity) {
Example<MyEntity> example = Example.of(myEntity);
return findAll(example);
}
}
I use Query by Example mechanism from Spring Data. When I have fields without #Convert (like String name) it works. But when I have field with #Convert (AttributeConverter) like List<String> emails it causes InvalidDataAccessApiUsageException.
org.springframework.dao.InvalidDataAccessApiUsageException: Parameter value [abc#company.com] did not match expected type [java.util.List (n/a)]; nested exception is java.lang.IllegalArgumentException: Parameter value [abc#company.com] did not match expected type [java.util.List (n/a)]
at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:374) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:257) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:528) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61) ~[spring-tx-5.2.1.RELEASE.jar:5.2.1.RELEASE]
...
Caused by: java.lang.IllegalArgumentException: Parameter value [abc#company.com] did not match expected type [java.util.List (n/a)]
at org.hibernate.query.spi.QueryParameterBindingValidator.validate(QueryParameterBindingValidator.java:54) ~[hibernate-core-5.4.8.Final.jar:5.4.8.Final]
at org.hibernate.query.spi.QueryParameterBindingValidator.validate(QueryParameterBindingValidator.java:27) ~[hibernate-core-5.4.8.Final.jar:5.4.8.Final]
at org.hibernate.query.internal.QueryParameterBindingImpl.validate(QueryParameterBindingImpl.java:90) ~[hibernate-core-5.4.8.Final.jar:5.4.8.Final]
... 146 common frames omitted
(message is weird because I've tried search with that list: ["abc#company.com", "def#company.com"], but in message is only one email)
I've tried to implement transform in ExampleMatcher:
import org.springframework.data.domain.Example;
import org.springframework.data.domain.ExampleMatcher;
public interface MyRepository extends JpaRepository<MyEntity, Long> {
default List<MyEntity> findMatchingMyEntity(MyEntity myEntity) {
ExampleMatcher matcher = ExampleMatcher.matching()
.withMatcher("emails",
match -> match.transform(emailsOptional -> {
if (emailsOptional.isPresent()) {
List<String> emails = (List<String>) emailsOptional.get();
return Optional.ofNullable(new StringListConverter().convertToDatabaseColumn(emails));
}
return emailsOptional;
}));
Example<MyEntity> example = Example.of(myEntity, matcher);
return findAll(example);
}
}
But is causes InvalidDataAccessApiUsageException too, but with different message than previous one (there are two emails that I've set):
org.springframework.dao.InvalidDataAccessApiUsageException: Parameter value [abc#company.com;def#company.com] did not match expected type [java.util.List (n/a)]; nested exception is java.lang.IllegalArgumentException: Parameter value [abc#company.com;def#company.com] did not match expected type [java.util.List (n/a)]
at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:374) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:257) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:528) ~[spring-orm-5.2.1.RELEASE.jar:5.2.1.RELEASE]
Caused by: java.lang.IllegalArgumentException: Parameter value [abc#company.com;def#company.com] did not match expected type [java.util.List (n/a)]
at org.hibernate.query.spi.QueryParameterBindingValidator.validate(QueryParameterBindingValidator.java:54) ~[hibernate-core-5.4.8.Final.jar:5.4.8.Final]
at org.hibernate.query.spi.QueryParameterBindingValidator.validate(QueryParameterBindingValidator.java:27) ~[hibernate-core-5.4.8.Final.jar:5.4.8.Final]
... 146 common frames omitted
It seems that for some reason Hibernate is trying to split the array of emails into multiple conditions just like in IN query in SQL using expandListValuedParameters method.
Note - with your solution doing query like findAllByEmailsIn(List<String> emailsList) also won't work.
Method expandListValuedParameters is deprecated since Hibernate 5.2, so it may contains some problems and for sure will be implemented differently in Hibernate 6.0.
I haven't found a fix for your problem, but there are some workarounds:
Wrap your List<String> emails in another class
Wrapper class:
public class EmailList {
private List<String> emails;
// getters, setters, constructors ommited
}
Updated model class:
import javax.persistence.Convert;
#Entity(name = "my_entity")
public class MyEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;
#Convert(converter = StringEmailListConverter.class)
private EmailList emailList;
// next fields omitted...
}
Updated converter class:
import javax.persistence.Converter;
#Converter
public class StringEmailListConverter implements AttributeConverter<EmailList, String> {
private static final String SPLIT_CHAR = ";";
#Override
public String convertToDatabaseColumn(EmailList emailList) {
if (emailList != null && CollectionUtils.isNotEmpty(emailList.getEmails())) {
return String.join(SPLIT_CHAR, emailList.getEmails());
} else {
return null;
}
}
#Override
public EmailList convertToEntityAttribute(String string) {
if (StringUtils.isNotBlank(string)) {
return new EmailList(Arrays.asList(string.split(SPLIT_CHAR)));
} else {
return new EmailList(Collections.emptyList());
}
}
}
And Spring Data repository will work fine with this code - no need for using transform:
import org.springframework.data.domain.Example;
public interface MyRepository extends JpaRepository<MyEntity, Long> {
default List<MyEntity> findMatchingMyEntity(MyEntity myEntity) {
Example<MyEntity> example = Example.of(myEntity);
return findAll(example);
}
}
Use String[] emails instead of List<String> emails
You need to change MyEntity and Converter respectively to use String[]. Of course using String[] sometimes is not an option because you specifically need a List.
I have a class that represents a user date of birth in two separated fields
public class User {
private int yearOfBirth;
private int monthOfBirth;
}
Is it possible to make a projection that exports the user age? I know we can concatenate fields using #Value.
The easiest way to resolve the problem (if you can add code to the domain class) is to add a method in the user class like the one below:
#JsonIgnore
public int getAge() {
return Period.between(
LocalDate.of(dobYear, dobMonth, 1),
LocalDate.now()
).getYears();
}
You can add the #JsonIgnore to block spring from exporting an "age" field when your entity is serialized. After adding that method you can create projection like the one below:
#Projection(name = "userAge ", types = {User.class})
public interface UserAge {
#Value("#{target.getAge()}")
Integer getAge();
}
Something like this, for example:
public class UserAgeDto {
private int yearOfBirth;
private int monthOfBirth;
public UserAgeDto(int yearOfBirth, int monthOfBirth) {
// constructor implementation...
}
public int getAge() {
// age calculation...
}
}
public interface UserRepo extends JpaRepository<User, Long> {
#Query("select new com.example.myapp.dto.UserAgeDto(u.yearOfBirth, u.monthOfBirth) from User u where u = ?")
UserAgeDto getUserAgeDto(User user);
}
Some info
I am using the hibernate validator group sequence and want to execute the groups in a sequence based on business rules. But the input to the groupSequenceProvider for its getValidationGroups is always null, and hence custom sequence never gets added.
My request object:
#GroupSequenceProvider(BeanSequenceProvider.class)
public class MyBean {
#NotEmpty
private String name;
#NotNull
private MyType type;
#NotEmpty(groups = Special.class)
private String lastName;
// Getters and setters
}
Enum type:
public enum MyType {
FIRST, SECOND
}
My custom sequence provider:
public class BeanSequenceProvider implements DefaultGroupSequenceProvider<MyBean> {
#Override
public List<Class<?>> getValidationGroups(MyBean object) {
final List<Class<?>> classes = new ArrayList<>();
classes.add(MyBean.class);
if (object != null && object.getType() == MyType.SECOND) {
classes.add(Special.class);
}
return classes;
}
}
Group annotation:
public interface Special {
}
When I execute the above code, I get the input MyBean object as null and cannot add the custom sequence. What am I missing? I am using hibernate-validator version as 5.4.1.Final
Is it possible to use Jersey with Moxy to/from Json and Java 8 Optionals?
How to configure it?
You can declare following class:
public class OptionalAdapter<T> extends XmlAdapter<T, Optional<T>> {
#Override
public Optional<T> unmarshal(T value) throws Exception {
return Optional.ofNullable(value);
}
#Override
public T marshal(Optional<T> value) throws Exception {
return value.orElse(null);
}
}
And use like this:
#XmlRootElement
public class SampleRequest {
#XmlElement(type = Integer.class)
#XmlJavaTypeAdapter(value = OptionalAdapter.class)
private Optional<Integer> id;
#XmlElement(type = String.class)
#XmlJavaTypeAdapter(value = OptionalAdapter.class)
private Optional<String> text;
/* ... */
}
Or declare in package-info.java and remove #XmlJavaTypeAdapter from POJOs:
#XmlAccessorType(XmlAccessType.FIELD)
#XmlJavaTypeAdapters({
#XmlJavaTypeAdapter(type = Optional.class, value = OptionalAdapter.class)
})
But here are some drawbacks:
Adapter above can only work with simple types like Integer, String, etc. that can be parsed by MOXY by default.
You have to specify #XmlElement(type = Integer.class) explicitly to tell the parser type are working with, otherwise null values would be passed to adapter's unmarshal method.
You miss the opportunity of using adapters for custom types, e.g. custom adapter for java.util.Date class based on some date format string. To overcome this you'll need to create adapter something like class OptionalDateAdapter<String> extends XmlAdapter<String, Optional<Date>>.
Also using Optional on field is not recommended, see this discussion for details.
Taking into account all the above, I would suggest just using Optional as return type for your POJOs:
#XmlRootElement
public class SampleRequest {
#XmlElement
private Integer id;
public Optional<Integer> getId() {
return Optional.ofNullable(id);
}
public void setId(Integer id) {
this.id = id;
}
}
Imagine that we have an entity:
#Entity
public class Person implements Serializable {
#Id
private String name;
private Long age;
private Boolean isMad;
...
}
And a repository with a trivial (and unnecessary) example for a custom query:
#Repository
public interface PersonRepository extends PagingAndSortingRepository<Info, String> {
#Query("select p.isMad, count(*) from Person p group by p.isMad")
List<Object> aggregateByMadness();
}
Now to parse this List we need to do something like this:
for (Object element : list) {
Object[] result = (Object[]) element;
Boolean isMad = (Boolean) result[0];
Long count = (Long) result[1];
}
which is a pain, can we cast the result of the query directly to List of a POJO?
Yes, you could use the JPQL construction expression:
package com.foo;
public class Madness {
public Madness(boolean isMad, Number count) { /* ...*/ }
}
And in your repository:
#Query("select new com.foo.Madness(p.isMad, count(*)) from Person p group by p.isMad")
List<Madness> aggregateByMadness();