title: How to determine spring data JPA is executed?
body: <p>I am trying to extend JPARepository in spring boot 2.5.3 and h2 database.</p>
  <pre><code>@Repository
  public interface CustomerRepository extends JpaRepository&lt;Customer, Long&gt; {
        boolean deleteCustomerById(Long id);
  }
  </code></pre>
  <p>Returning a boolean because service and controller needs to know if it was successful operation and send appropriate response entity.</p>
  <pre><code> public boolean delete(Long id) {
          return customerRepository.deleteCustomerById(id);
      }
  </code></pre>
  <p>Controller</p>
  <pre><code>@DeleteMapping(path = &quot;/customers/{id}&quot;)
  public ResponseEntity&lt;?&gt; deleteCustomer(@PathVariable(&quot;id&quot;) Long id){
      Optional&lt;Customer&gt; foundCustomer= customerService.findById(id);
      return foundCustomer.map(customer -&gt; {
          if (customerService.delete(id)){
              return ResponseEntity.ok().build();
          }else {
              return ResponseEntity.internalServerError().build();
          }
      }).orElse(ResponseEntity.notFound().build());
  }
  </code></pre>
  <p>Doing this way gives an error while testing the repository.</p>
  <pre><code>@Test
  public void deleteCustomerByIdSuccess(){
      boolean result=customerRepository.deleteCustomerById(1L);
      assertTrue(result,&quot;Customer should be deleted successfully&quot;);
      Optional&lt;Customer&gt; foundCustomer=customerRepository.findById(1L);
      assertFalse(foundCustomer.isPresent(),&quot;Customer 1 should be deleted and not be found.&quot;);
  }
  </code></pre>
  <p>Error:</p>
  <pre><code>java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Boolean (java.lang.Integer and java.lang.Boolean are in module java.base of loader 'bootstrap')
  
      at com.sun.proxy.$Proxy92.deleteCustomerById(Unknown Source)
      at com.prabhakar.customer.repository.CustomerRepositoryTest.deleteCustomerByIdSuccess(CustomerRepositoryTest.java:67)
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.base/java.lang.reflect.Method.invoke(Method.java:566)
      at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
      at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
      at org.junit.jupiter.engine.execution.InvocationInterceptorChain$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$6(TestMethodTestDescriptor.java:210)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:206)
      at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
      at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
      at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
      at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
      at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
      at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
      at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
      at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
      at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
      at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
      at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
      at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
      at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
      at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
      at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
      at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
      at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
      at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
      at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
      at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:75)
      at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
      at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
      at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:221)
      at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
  </code></pre>
  <p>But when I change repository to:</p>
  <pre><code>@Repository
  public interface CustomerRepository extends JpaRepository&lt;Customer, Long&gt; {
        int deleteCustomerById(Long id);
  }
  </code></pre>
  <p>And validate with 1 it works.</p>
  <p>There is a default deleteById method but it returns void.</p>
  <pre><code>void deleteById(ID var1);
  </code></pre>
  <p>It want it to return a boolean,so I tried to use my own Implementaion as above.</p>
  <p>What does Spring data JPA use internally?(Is it executeUpdate?)
  I can see the logs, and the SQL queries but how do we come to know if it has been executed or by returning void.</p>