Use Enum for CustomerState

customer-api-provider/src/main/java/de/schulung/sample/quarkus/Customer.java

@@ -1,6 +1,7 @@
 package de.schulung.sample.quarkus;
 
 import jakarta.json.bind.annotation.JsonbTransient;
+import jakarta.json.bind.annotation.JsonbTypeAdapter;
 import lombok.AllArgsConstructor;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
@@ -20,6 +21,16 @@ public class Customer {
   private UUID uuid;
   private String name;
   private LocalDate birthdate; // TODO birth_date?
-  private String state;
+  @JsonbTypeAdapter(CustomerStateAdapter.class) // TODO register globally?
+  private CustomerState state = CustomerState.ACTIVE;
+
+  // Would work without any adapter, if the name() matches the JSON value.
+  // Here: "active", "locked" and "disabled".
+  //  - DON'T: This would break with Java naming conventions.
+  public enum CustomerState {
+
+    ACTIVE, LOCKED, DISABLED
+
+  }
 
 }

customer-api-provider/src/main/java/de/schulung/sample/quarkus/CustomerStateAdapter.java

@@ -0,0 +1,30 @@
+package de.schulung.sample.quarkus;
+
+import jakarta.json.bind.adapter.JsonbAdapter;
+
+/*
+ * A more generic mapper is not possible easily, because
+ *  - the adapter doesn't have any information about the mapped field (target type)
+ *  - we need to be careful with reflection (GraalVM!)
+ */
+public class CustomerStateAdapter implements JsonbAdapter<Customer.CustomerState, String> {
+
+  @Override
+  public String adaptToJson(Customer.CustomerState source) throws Exception {
+    return null == source ? null : switch (source) {
+      case ACTIVE -> "active";
+      case LOCKED -> "locked";
+      case DISABLED -> "disabled";
+    };
+  }
+
+  @Override
+  public Customer.CustomerState adaptFromJson(String source) throws Exception {
+    return null == source ? null : switch (source) {
+      case "active" -> Customer.CustomerState.ACTIVE;
+      case "locked" -> Customer.CustomerState.LOCKED;
+      case "disabled" -> Customer.CustomerState.DISABLED;
+      default -> throw new IllegalArgumentException(source + " is not supported.");
+    };
+  }
+}

customer-api-provider/src/main/java/de/schulung/sample/quarkus/CustomersResource.java

@@ -22,7 +22,7 @@ public class CustomersResource {
       UUID.randomUUID(),
       "Tom",
       LocalDate.of(2000, Month.DECEMBER, 6),
-      "active"
+      Customer.CustomerState.ACTIVE
     );
     customers.put(customer.getUuid(), customer);
   }

customer-api-provider/src/test/java/de/schulung/sample/quarkus/CustomerApiTests.java

@@ -77,6 +77,7 @@ void shouldCreateCustomer() {
         .contentType(ContentType.JSON)
         .body("name", is(equalTo("Tom")))
         .body("birthdate", is(equalTo("2000-10-04")))
+        .body("state", is(equalTo("active")))
         .body("uuid", is(notNullValue()))
         .extract()
         .header("Location");
@@ -91,5 +92,24 @@ void shouldCreateCustomer() {
         .body("birthdate", is(equalTo("2000-10-04")));
     }
 
+    @Test
+    void shouldNotCreateCustomerWithInvalidState() {
+      var location = given()
+        .when()
+        .contentType(ContentType.JSON)
+        .body("""
+                {
+                    "name": "Tom",
+                    "birthdate": "2000-10-04",
+                    "state": "gelbekatze"
+                }
+                """)
+        .accept(ContentType.JSON)
+        .post("/customers")
+        .then()
+        .statusCode(400);
+
+    }
+
   }
 }