From 16fd809e4e5abd9dd2eb4a80cb3436f0e2b457b0 Mon Sep 17 00:00:00 2001
From: nosix <nosix@users.noreply.github.com>
Date: Wed, 4 Nov 2020 13:25:01 +0900
Subject: [PATCH] Fix: Response was null but response body type was declared as
 non-null

https://github.com/square/retrofit/issues/3075
---
 .../src/main/kotlin/com/example/api/CustomerService.kt    | 2 +-
 backend-api/src/main/kotlin/com/example/api/Optional.kt   | 8 ++++++++
 .../com/example/backend/controller/CustomerController.kt  | 5 +++--
 .../test/kotlin/com/example/backend/CustomerApiTests.kt   | 2 +-
 4 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 backend-api/src/main/kotlin/com/example/api/Optional.kt

diff --git a/backend-api/src/main/kotlin/com/example/api/CustomerService.kt b/backend-api/src/main/kotlin/com/example/api/CustomerService.kt
index 7b5ac45..a47139f 100644
--- a/backend-api/src/main/kotlin/com/example/api/CustomerService.kt
+++ b/backend-api/src/main/kotlin/com/example/api/CustomerService.kt
@@ -11,7 +11,7 @@ interface CustomerService {
     suspend fun getAllCustomers(): List<Customer>
 
     @GET("customers/{id}")
-    suspend fun getCustomer(@Path("id") id: Long): Customer?
+    suspend fun getCustomer(@Path("id") id: Long): Optional<Customer>
 
     @GET("customers/search")
     suspend fun getCustomersByLastName(
diff --git a/backend-api/src/main/kotlin/com/example/api/Optional.kt b/backend-api/src/main/kotlin/com/example/api/Optional.kt
new file mode 100644
index 0000000..d245469
--- /dev/null
+++ b/backend-api/src/main/kotlin/com/example/api/Optional.kt
@@ -0,0 +1,8 @@
+package com.example.api
+
+import kotlinx.serialization.Serializable
+
+// FIXME https://github.com/square/retrofit/issues/3075
+
+@Serializable
+data class Optional<T>(val unboxed: T?)
\ No newline at end of file
diff --git a/backend/src/main/kotlin/com/example/backend/controller/CustomerController.kt b/backend/src/main/kotlin/com/example/backend/controller/CustomerController.kt
index 559eba5..64be850 100644
--- a/backend/src/main/kotlin/com/example/backend/controller/CustomerController.kt
+++ b/backend/src/main/kotlin/com/example/backend/controller/CustomerController.kt
@@ -2,6 +2,7 @@ package com.example.backend.controller
 
 import com.example.api.Customer
 import com.example.api.CustomerService
+import com.example.api.Optional
 import com.example.backend.repository.CustomerRepository
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
@@ -32,8 +33,8 @@ class CustomerController(
     @GetMapping("customers/{id}")
     override suspend fun getCustomer(
         @PathVariable("id") id: Long
-    ): Customer? {
-        return repository.findById(id)?.asApi()
+    ): Optional<Customer> {
+        return Optional(repository.findById(id)?.asApi())
     }
 
     @GetMapping("customers/search")
diff --git a/backend/src/test/kotlin/com/example/backend/CustomerApiTests.kt b/backend/src/test/kotlin/com/example/backend/CustomerApiTests.kt
index 98c6d77..d6065ed 100644
--- a/backend/src/test/kotlin/com/example/backend/CustomerApiTests.kt
+++ b/backend/src/test/kotlin/com/example/backend/CustomerApiTests.kt
@@ -106,7 +106,7 @@ class CustomerApiTests {
         Mockito
             .`when`(customerRepository.findById(1))
             .thenReturn(entity)
-        val customer = customerService.getCustomer(1)
+        val customer = customerService.getCustomer(1).unboxed
         assertEquals(expected, customer)
     }