Constraint violation when reading data - spring-boot

Question

I am writing integration tests with junit-jupiter and something very strange is happening -> Constraint violation exception occurs when I am reading (not saving the data)
storesTemplateRepository.findByCountryOrderByTemplateName(country, pageable); raises the following exception:
could not execute statement; SQL [n/a]; constraint ["PRIMARY KEY ON PUBLIC.STORES_TEMPLATE(ID)"; SQL statement:
insert into stores_template (country, stores, template_name, id) values (?, ?, ?, ?) [23505-196]]
Entity:
#Entity
#Getter
#Setter
#NoArgsConstructor
#Table(name = "STORES_TEMPLATE")
public class StoresTemplate {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "STORES_TEMPLATE_ID_SEQ")
#SequenceGenerator(name = "STORES_TEMPLATE_ID_SEQ", sequenceName = "STORES_TEMPLATE_ID_SEQ", allocationSize = 1)
private long id;
#Enumerated(EnumType.STRING)
private CountryEnum country;
private String templateName;
#Lob
private String stores;
public void setStores(List<String> stores) {
this.stores = String.join(",", stores);
}
#JsonIgnore
public List<String> getStoresAsList() {
return Arrays.stream(stores.split(","))
.distinct()
.collect(Collectors.toList());
}
}
Test
#Slf4j
#Transactional
#SpringBootTest
public class StoresTemplateControllerTest {
#Autowired
private WebApplicationContext context;
#Autowired
private ObjectMapper objectMapper;
#Autowired
private StoresTemplateRepository storesTemplateRepository;
private MockMvc mockMvc;
#BeforeEach
public void setUp() {
mockMvc = MockMvcBuilders
.webAppContextSetup(context)
.apply(SecurityMockMvcConfigurers.springSecurity())
.build();
}
#Test
public void fullApiTest() {
OAuth2AuthenticationToken dePrincipal = new TestDataBuilder()
.createOAuth2AuthenticationToken()
.setDefaultStoreUser()
.setRoles(SiamRoles.DE_CREATOR_ADMIN)
.build();
CreateStoresTemplateDto createStoresTemplateDeDto = CreateStoresTemplateDto.builder()
.country(CountryEnum.DE)
.stores(List.of("de1000", "de1100"))
.templateName("de template")
.build();
CreateStoresTemplateDto createStoresTemplateBgDto = CreateStoresTemplateDto.builder()
.country(CountryEnum.BG)
.stores(List.of("bg2000", "bg2100"))
.templateName("bg template")
.build();
CreateStoresTemplateDto createStoresTemplateDefaultDto = CreateStoresTemplateDto.builder()
.country(null)
.stores(List.of("de3000", "de3100"))
.templateName("default template")
.build();
try {
// find all existing by predefined insertion script
for (long id: findAll(dePrincipal, CountryEnum.DE).map(e -> e.id)) {
storesTemplateRepository.deleteById(id);
}
storesTemplateRepository.save(StoresTemplateMapper.toStoresTemplate(createStoresTemplateDeDto));
storesTemplateRepository.findByCountryOrderByTemplateName(CountryEnum.DE);
storesTemplateRepository.save(StoresTemplateMapper.toStoresTemplate(createStoresTemplateBgDto));
storesTemplateRepository.findByCountryOrderByTemplateName(CountryEnum.DE); // Here the exception occurs
storesTemplateRepository.save(StoresTemplateMapper.toStoresTemplate(createStoresTemplateDefaultDto));
storesTemplateRepository.findByCountryOrderByTemplateName(CountryEnum.DE);
} catch (Exception e) {
e.printStackTrace();
fail(e.getMessage());
}
}
}

Answer 1

JPA/Hibernate queues the operations in its session whenever possible, does not call the database instantly and then just before the transaction is completing, order those operations based on type and execute them. This is called Transactional write-behind in hibernate. As you can see, even though you called the delete first, hibernate will order it as last if it was queued.
Inserts, in the order they were performed
Updates
Deletion of collection elements
Insertion of collection elements
Deletes, in the order they were performed
So even though you do delete first as you can see hibernate will do it last. If you want to control the order, you need to flush it. So do the following.
for (long id: findAll(dePrincipal, CountryEnum.DE).map(e -> e.id)) {
storesTemplateRepository.deleteById(id);
}
storesTemplateRepository.flush();
Reference
Executions Order