BAEl 2803 (#6574)

* BAEL-2803 Sample Code

* updated tests, repo method names

* moved sources for BAEL-2803 here

* removed dependencies introduced by BAEL-2803

* re-added sources

* renamed test methods according to BDD

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/exists/Car.java

@@ -0,0 +1,48 @@
+package com.baeldung.exists;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+/**
+ * @author paullatzelsperger
+ * @since 2019-03-20
+ */
+@Entity
+public class Car {
+
+    @Id
+    @GeneratedValue
+    private int id;
+    private Integer power;
+    private String model;
+
+    Car() {
+
+    }
+
+    public Car(int power, String model) {
+        this.power = power;
+        this.model = model;
+    }
+
+    public Integer getPower() {
+        return power;
+    }
+
+    public void setPower(Integer power) {
+        this.power = power;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    public int getId() {
+        return id;
+    }
+}

persistence-modules/spring-boot-persistence/src/main/java/com/baeldung/exists/CarRepository.java

@@ -0,0 +1,24 @@
+package com.baeldung.exists;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
+import org.springframework.stereotype.Repository;
+
+/**
+ * @author paullatzelsperger
+ * @since 2019-03-20
+ */
+@Repository
+public interface CarRepository extends JpaRepository<Car, Integer> {
+
+    boolean existsCarByPower(int power);
+
+    boolean existsCarByModel(String model);
+
+    @Query("select case when count(c)> 0 then true else false end from Car c where c.model = :model")
+    boolean existsCarExactCustomQuery(@Param("model") String model);
+
+    @Query("select case when count(c)> 0 then true else false end from Car c where lower(c.model) like lower(:model)")
+    boolean existsCarLikeCustomQuery(@Param("model") String model);
+}

persistence-modules/spring-boot-persistence/src/test/java/com/baeldung/exists/CarRepositoryIntegrationTest.java

@@ -0,0 +1,86 @@
+package com.baeldung.exists;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.data.domain.ExampleMatcher.GenericPropertyMatchers.ignoreCase;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.data.domain.Example;
+import org.springframework.data.domain.ExampleMatcher;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.util.Arrays;
+import java.util.List;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class CarRepositoryIntegrationTest {
+
+    @Autowired
+    private CarRepository repository;
+    private int searchId;
+
+    @Before
+    public void setup() {
+        List<Car> cars = repository.saveAll(Arrays.asList(new Car(200, "BMW"), new Car(300, "Audi")));
+        searchId = cars.get(0).getId();
+    }
+
+    @After
+    public void teardown() {
+        repository.deleteAll();
+    }
+
+    @Test
+    public void whenIdIsCorrect_thenExistsShouldReturnTrue() {
+        assertThat(repository.existsById(searchId)).isTrue();
+    }
+
+    @Test
+    public void givenExample_whenExists_thenIsTrue() {
+        ExampleMatcher modelMatcher = ExampleMatcher.matching()
+                .withIgnorePaths("id") // must explicitly ignore -> PK
+                .withMatcher("model", ignoreCase());
+        Car probe = new Car();
+        probe.setModel("bmw");
+
+        Example<Car> example = Example.of(probe, modelMatcher);
+
+        assertThat(repository.exists(example)).isTrue();
+    }
+
+    @Test
+    public void givenPower_whenExists_thenIsFalse() {
+        assertThat(repository.existsCarByPower(200)).isTrue();
+        assertThat(repository.existsCarByPower(800)).isFalse();
+    }
+
+    @Test
+    public void existsByDerivedQuery_byModel() {
+        assertThat(repository.existsCarByModel("Audi")).isTrue();
+        assertThat(repository.existsCarByModel("audi")).isFalse();
+        assertThat(repository.existsCarByModel("AUDI")).isFalse();
+        assertThat(repository.existsCarByModel("")).isFalse();
+    }
+
+    @Test
+    public void givenModelName_whenExistsExact_thenIsTrue() {
+        assertThat(repository.existsCarExactCustomQuery("BMW")).isTrue();
+        assertThat(repository.existsCarExactCustomQuery("Bmw")).isFalse();
+        assertThat(repository.existsCarExactCustomQuery("bmw")).isFalse();
+        assertThat(repository.existsCarExactCustomQuery("")).isFalse();
+    }
+
+    @Test
+    public void givenModelName_whenExistsLike_thenIsTrue() {
+        assertThat(repository.existsCarLikeCustomQuery("BMW")).isTrue();
+        assertThat(repository.existsCarLikeCustomQuery("Bmw")).isTrue();
+        assertThat(repository.existsCarLikeCustomQuery("bmw")).isTrue();
+        assertThat(repository.existsCarLikeCustomQuery("")).isFalse();
+    }
+
+}