H2 DB

- used for tests
- no DB implenention for prod

build.gradle

@@ -8,7 +8,7 @@ group = 'djmil'
 version = '0.0.1-SNAPSHOT'
 
 java {
-	sourceCompatibility = '17'
+	sourceCompatibility = '20'
 }
 
 repositories {
@@ -18,8 +18,26 @@ repositories {
 dependencies {
 	implementation 'org.springframework.boot:spring-boot-starter-web'
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
+
+	implementation 'org.springframework.data:spring-data-jdbc'
+    testImplementation 'com.h2database:h2'
 }
 
 tasks.named('test') {
 	useJUnitPlatform()
 }
+
+// This section causes useful test output to go to the terminal.
+test {
+    testLogging {
+        events "passed", "skipped", "failed" //, "standardOut", "standardError"
+
+        showExceptions true
+        exceptionFormat "full"
+        showCauses true
+        showStackTraces true
+
+        // Change to `true` for more verbose test output
+        showStandardStreams = false
+    }
+}

src/main/java/djmil/cashcard/CashCard.java

@@ -1,5 +1,6 @@
 package djmil.cashcard;
 
-public record CashCard(Long id, Double amount) {
+import org.springframework.data.annotation.Id;
 
+public record CashCard(@Id Long id, Double amount) {
 }

src/main/java/djmil/cashcard/CashCardController.java

@@ -6,15 +6,24 @@ import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
+import java.util.Optional;
+
 @RestController
 @RequestMapping("/cashcards")
 public class CashCardController {
 
+    private CashCardRepository cashCardRepository;
+
+    public CashCardController(CashCardRepository cashCardRepository) {
+        this.cashCardRepository = cashCardRepository;
+    }
+
     @GetMapping("/{requestedId}")
     public ResponseEntity<CashCard> findById(@PathVariable Long requestedId) {
-        if (requestedId.equals(99L)) {
-            CashCard cashCard = new CashCard(99L, 123.45);
-            return ResponseEntity.ok(cashCard);
+        Optional<CashCard> cashCardOptional = cashCardRepository.findById(requestedId);
+
+        if (cashCardOptional.isPresent()) {
+            return ResponseEntity.ok(cashCardOptional.get());
         } else {
             return ResponseEntity.notFound().build();
         }

src/main/java/djmil/cashcard/CashCardRepository.java

@@ -0,0 +1,6 @@
+package djmil.cashcard;
+
+import org.springframework.data.repository.CrudRepository;
+
+public interface CashCardRepository extends CrudRepository<CashCard, Long> {
+}

src/test/resources/data.sql

@@ -0,0 +1 @@
+INSERT INTO CASH_CARD(ID, AMOUNT) VALUES (99, 123.45);

src/test/resources/schema.sql

@@ -0,0 +1,5 @@
+CREATE TABLE cash_card
+(
+   ID     BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
+   AMOUNT NUMBER NOT NULL DEFAULT 0
+);