Add cachePolicyResponseMapper

Author: BoD

normalized-cache/src/commonMain/kotlin/com/apollographql/cache/normalized/ClientCacheExtensions.kt

@@ -753,3 +753,27 @@ fun <T> MutableExecutionOptions<T>.clock(clock: () -> Long): T {
   @Suppress("UNCHECKED_CAST")
   return this as T
 }
+
+internal class CachePolicyResponseMapperContext(val value: (ApolloResponse<*>, FetchPolicy) -> ApolloResponse<*>) :
+  ExecutionContext.Element {
+  override val key: ExecutionContext.Key<*>
+    get() = Key
+
+  companion object Key : ExecutionContext.Key<CachePolicyResponseMapperContext>
+}
+
+private val defaultCachePolicyResponseMapper: (ApolloResponse<*>, FetchPolicy) -> ApolloResponse<*> = { response, _ ->
+  response.errorsAsException()
+}
+
+internal val ExecutionOptions.cachePolicyResponseMapper: ((ApolloResponse<*>, FetchPolicy) -> ApolloResponse<*>)
+  get() = executionContext[CachePolicyResponseMapperContext]?.value ?: defaultCachePolicyResponseMapper
+
+/**
+ * Sets a response mapper that will be used inside the built-in fetch policies interceptors to transform the responses from the cache.
+ */
+fun <T> MutableExecutionOptions<T>.cachePolicyResponseMapper(mapper: (ApolloResponse<*>, FetchPolicy) -> ApolloResponse<*>): T {
+  addExecutionContext(CachePolicyResponseMapperContext(mapper))
+  @Suppress("UNCHECKED_CAST")
+  return this as T
+}

normalized-cache/src/commonMain/kotlin/com/apollographql/cache/normalized/FetchPolicyInterceptors.kt

@@ -33,7 +33,10 @@ val CacheOnlyInterceptor = object : ApolloInterceptor {
             .newBuilder()
             .fetchFromCache(true)
             .build()
-    ).map { it.errorsAsException() }
+    ).map {
+      @Suppress("UNCHECKED_CAST")
+      request.cachePolicyResponseMapper(it, FetchPolicy.CacheOnly) as ApolloResponse<D>
+    }
   }
 }
 
@@ -57,7 +60,10 @@ val CacheFirstInterceptor = object : ApolloInterceptor {
               .newBuilder()
               .fetchFromCache(true)
               .build()
-      ).single().errorsAsException()
+      ).single().let {
+        @Suppress("UNCHECKED_CAST")
+        request.cachePolicyResponseMapper(it, FetchPolicy.CacheFirst) as ApolloResponse<D>
+      }
       emit(cacheResponse.newBuilder().isLast(cacheResponse.exception == null).build())
       if (cacheResponse.exception == null) {
         return@flow
@@ -103,7 +109,10 @@ val NetworkFirstInterceptor = object : ApolloInterceptor {
               .newBuilder()
               .fetchFromCache(true)
               .build()
-      ).single().errorsAsException()
+      ).single().let {
+        @Suppress("UNCHECKED_CAST")
+        request.cachePolicyResponseMapper(it, FetchPolicy.NetworkFirst) as ApolloResponse<D>
+      }
       emit(cacheResponse)
     }
   }
@@ -120,7 +129,10 @@ val CacheAndNetworkInterceptor = object : ApolloInterceptor {
               .newBuilder()
               .fetchFromCache(true)
               .build()
-      ).single().errorsAsException()
+      ).single().let {
+        @Suppress("UNCHECKED_CAST")
+        request.cachePolicyResponseMapper(it, FetchPolicy.CacheAndNetwork) as ApolloResponse<D>
+      }
 
       emit(cacheResponse.newBuilder().isLast(false).build())
 

tests/cache-policy-response-mapper/build.gradle.kts

@@ -0,0 +1,51 @@
+import com.apollographql.apollo.annotations.ApolloExperimental
+
+plugins {
+  alias(libs.plugins.kotlin.multiplatform)
+  id("com.apollographql.apollo")
+}
+
+kotlin {
+  configureKmp(
+      withJs = emptySet(),
+      withWasm = emptySet(),
+      withAndroid = false,
+      withApple = AppleTargets.Host,
+  )
+
+  sourceSets {
+    getByName("commonMain") {
+      dependencies {
+        implementation(libs.apollo.runtime)
+        implementation("com.apollographql.cache:normalized-cache-sqlite")
+      }
+    }
+
+    getByName("commonTest") {
+      dependencies {
+        implementation("com.apollographql.cache:test-utils")
+        implementation(libs.apollo.mockserver)
+        implementation(libs.kotlin.test)
+      }
+    }
+
+    getByName("jvmTest") {
+      dependencies {
+        implementation(libs.slf4j.nop)
+      }
+    }
+  }
+}
+
+apollo {
+  service("service") {
+    packageName.set("test")
+
+    @OptIn(ApolloExperimental::class)
+    plugin("com.apollographql.cache:normalized-cache-apollo-compiler-plugin") {
+      argument("packageName", packageName.get())
+    }
+
+    mapScalar("Category", "test.Category", "test.CategoryAdapter")
+  }
+}

tests/cache-policy-response-mapper/src/commonMain/graphql/extra.graphqls

@@ -0,0 +1,7 @@
+extend schema
+@link(
+  url: "https://specs.apollo.dev/kotlin_labs/v0.5",
+  import: ["@typePolicy", "@fieldPolicy"]
+)
+
+extend type User @typePolicy(keyFields: "id")

tests/cache-policy-response-mapper/src/commonMain/graphql/operation.graphql

@@ -0,0 +1,109 @@
+query MeWithNickNameQuery {
+  me {
+    id
+    firstName
+    lastName
+    nickName
+  }
+}
+
+query MeWithNickNameAndProjectQuery {
+  me {
+    id
+    firstName
+    lastName
+    nickName
+    bestFriend {
+      id
+      firstName
+      lastName
+    }
+  }
+}
+
+query UsersQuery($ids: [ID!]!) {
+  users(ids: $ids) {
+    id
+    firstName
+    lastName
+    email
+  }
+}
+
+query MeWithBestFriendQuery {
+  me {
+    id
+    firstName
+    lastName
+    bestFriend {
+      id
+      firstName
+      lastName
+    }
+    projects {
+      lead {
+        id
+        firstName
+        lastName
+      }
+      users {
+        id
+        firstName
+        lastName
+      }
+    }
+  }
+}
+
+query DefaultProjectQuery($id: ID! = "42") {
+  project(id: $id) {
+    id
+    name
+    description
+  }
+  project2: project(id: "44") {
+    id
+    name
+    description
+  }
+}
+
+query WithFragmentsQuery {
+  me {
+    id
+    firstName0: firstName
+    ... on User {
+      lastName
+      ... on User {
+        nickName0: nickName
+      }
+    }
+    ... UserFields
+  }
+
+  me {
+    firstName0: firstName
+    mainProject {
+      id
+      lead0: lead {
+        id
+      }
+    }
+    mainProject {
+      lead0: lead {
+        id
+        firstName
+      }
+    }
+  }
+}
+
+fragment UserFields on User {
+  email0: email
+  category
+  bestFriend0:bestFriend {
+    id
+    firstName
+    lastName
+  }
+}

tests/cache-policy-response-mapper/src/commonMain/graphql/schema.graphqls

@@ -0,0 +1,39 @@
+type Query {
+  me: User!
+  users(ids: [ID!]!): [User]!
+  project(id: ID! = "1"): Project
+  user(category: Category!): User!
+  someInt: Int
+  someInt2: Int
+}
+
+type User {
+  id: ID!
+  firstName: String!
+  lastName: String!
+  nickName: String
+  email: String!
+  bestFriend: User
+  projects: [Project!]!
+  mainProject: Project!
+  category: Category!
+  moreInfo: Json!
+  employeeInfo: EmployeeInfo
+}
+
+type Project {
+  id: ID!
+  name: String!
+  description: String
+  lead: User
+  users: [User!]!
+}
+
+type EmployeeInfo {
+  id: ID!
+  salary: Int
+  department: String
+}
+
+scalar Category
+scalar Json

tests/cache-policy-response-mapper/src/commonMain/kotlin/test/Category.kt

@@ -0,0 +1,35 @@
+package test
+
+import com.apollographql.apollo.api.Adapter
+import com.apollographql.apollo.api.CustomScalarAdapters
+import com.apollographql.apollo.api.json.JsonReader
+import com.apollographql.apollo.api.json.JsonWriter
+
+data class Category(
+    val code: Int,
+    val name: String,
+)
+
+val CategoryAdapter = object : Adapter<Category> {
+  override fun fromJson(reader: JsonReader, customScalarAdapters: CustomScalarAdapters): Category {
+    reader.beginObject()
+    var code: Int? = null
+    var name: String? = null
+    while (true) {
+      when (reader.selectName(listOf("code", "name"))) {
+        0 -> code = reader.nextInt()
+        1 -> name = reader.nextString()
+        else -> break
+      }
+    }
+    reader.endObject()
+    return Category(code = code!!, name = name!!)
+  }
+
+  override fun toJson(writer: JsonWriter, customScalarAdapters: CustomScalarAdapters, value: Category) {
+    writer.beginObject()
+    writer.name("code").value(value.code)
+    writer.name("name").value(value.name)
+    writer.endObject()
+  }
+}