Merge pull request #10489 from azhwani/BAEL-4168

BAEL-4168: No converter found for return value of type

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/NoConverterFoundApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.boot.noconverterfound;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class NoConverterFoundApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(NoConverterFoundApplication.class, args);
+    }
+}

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/controller/StudentRestController.java

@@ -0,0 +1,21 @@
+package com.baeldung.boot.noconverterfound.controller;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.baeldung.boot.noconverterfound.model.Student;
+
+@RestController
+@RequestMapping(value = "/api")
+public class StudentRestController {
+
+    @GetMapping("/student/{id}")
+    public ResponseEntity<Student> get(@PathVariable("id") int id) {
+        // Custom logic
+        return ResponseEntity.ok(new Student(id, "John", "Wiliams", "AA"));
+    }
+
+}

spring-boot-modules/spring-boot-data-2/src/main/java/com/baeldung/boot/noconverterfound/model/Student.java

@@ -0,0 +1,53 @@
+package com.baeldung.boot.noconverterfound.model;
+
+public class Student {
+
+    private int id;
+    private String firstName;
+    private String lastName;
+    private String grade;
+
+    public Student() {
+
+    }
+
+    public Student(int id, String firstName, String lastName, String grade) {
+        this.id = id;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.grade = grade;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public String getGrade() {
+        return grade;
+    }
+
+    public void setGrade(String grade) {
+        this.grade = grade;
+    }
+
+}

spring-boot-modules/spring-boot-data-2/src/test/java/com/baeldung/boot/noconverterfound/NoConverterFoundIntegrationTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.boot.noconverterfound;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.http.converter.HttpMessageNotWritableException;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+
+import com.baeldung.boot.noconverterfound.controller.StudentRestController;
+
+@RunWith(SpringRunner.class)
+@WebMvcTest(StudentRestController.class)
+public class NoConverterFoundIntegrationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    public void whenGettersNotDefined_thenThrowException() throws Exception {
+
+        String url = "/api/student/1";
+
+        this.mockMvc.perform(get(url))
+          .andExpect(status().isInternalServerError())
+          .andExpect(result -> assertThat(result.getResolvedException())
+            .isInstanceOf(HttpMessageNotWritableException.class))
+          .andExpect(result -> assertThat(result.getResolvedException().getMessage())
+            .contains("No converter found for return value of type"));
+
+    }
+
+    @Test
+    public void whenGettersAreDefined_thenReturnObject() throws Exception {
+
+        String url = "/api/student/2";
+
+        this.mockMvc.perform(get(url))
+          .andExpect(status().isOk())
+          .andExpect(jsonPath("$.firstName").value("John"));
+
+    }
+
+}