[FileUpload] Allow to encode custom scalar types as null and use it for file uploads

apollo-api/api.txt

@@ -115,6 +115,10 @@ package com.apollographql.apollo.api {
     method public error.NonExistentClass hashCode();
   }
 
+  public static final class CustomTypeValue.GraphQLNull extends com.apollographql.apollo.api.CustomTypeValue {
+    field public static final com.apollographql.apollo.api.CustomTypeValue.GraphQLNull INSTANCE;
+  }
+
   public static final class CustomTypeValue.GraphQLNumber extends com.apollographql.apollo.api.CustomTypeValue {
     ctor public CustomTypeValue.GraphQLNumber(error.NonExistentClass);
     method public error.NonExistentClass equals(error.NonExistentClass);

apollo-api/src/commonMain/kotlin/com/apollographql/apollo/api/CustomTypeValue.kt

@@ -9,6 +9,8 @@ import kotlin.jvm.JvmStatic
  **/
 sealed class CustomTypeValue<T>(@JvmField val value: T) {
 
+  object GraphQLNull: CustomTypeValue<Unit>(Unit)
+
   /**
    * Represents a `String` value
    */
@@ -91,6 +93,7 @@ sealed class CustomTypeValue<T>(@JvmField val value: T) {
 
   companion object {
 
+    // TODO: should this method accept nullable values in case a scalar type is represented as 'null'?
     @JvmStatic
     @Suppress("UNCHECKED_CAST")
     fun fromRawValue(value: Any): CustomTypeValue<*> {

apollo-api/src/commonMain/kotlin/com/apollographql/apollo/api/ScalarTypeAdapters.kt

@@ -84,11 +84,12 @@ class ScalarTypeAdapters(val customAdapters: Map<ScalarType, CustomTypeAdapter<*
         } +
         mapOf("com.apollographql.apollo.api.FileUpload" to object : CustomTypeAdapter<FileUpload> {
           override fun decode(value: CustomTypeValue<*>): FileUpload {
+            // TODO: is there a valid use case for decoding a FileUpload or should we throw here?
             return FileUpload("", value.value?.toString() ?: "")
           }
 
           override fun encode(value: FileUpload): CustomTypeValue<*> {
-            return GraphQLString(value.mimetype)
+            return GraphQLNull
           }
         }) +
         createDefaultScalarTypeAdapter("java.util.Map", "kotlin.collections.Map") { value ->

apollo-api/src/commonMain/kotlin/com/apollographql/apollo/api/internal/json/InputFieldJsonWriter.kt

@@ -80,6 +80,7 @@ class InputFieldJsonWriter(
       is GraphQLString -> writeString(fieldName, customTypeValue.value)
       is GraphQLBoolean -> writeBoolean(fieldName, customTypeValue.value)
       is GraphQLNumber -> writeNumber(fieldName, customTypeValue.value)
+      is GraphQLNull -> writeString(fieldName, null)
       is GraphQLJsonObject -> jsonWriter.name(fieldName).apply { writeToJson(customTypeValue.value, this) }
       is GraphQLJsonList -> jsonWriter.name(fieldName).apply { writeToJson(customTypeValue.value, this) }
     }
@@ -195,6 +196,7 @@ class InputFieldJsonWriter(
         is GraphQLNumber -> writeNumber(customTypeValue.value)
         is GraphQLJsonObject -> writeToJson(customTypeValue.value, jsonWriter)
         is GraphQLJsonList -> writeToJson(customTypeValue.value, jsonWriter)
+        is GraphQLNull -> writeString(null)
       }
     }
 

apollo-api/src/commonTest/kotlin/com/apollographql/apollo/api/internal/json/InputFieldJsonWriterTest.kt

@@ -130,6 +130,20 @@ class InputFieldJsonWriterTest {
     assertEquals("{\"someField\":\"someValue\",\"someNullField\":null", jsonBuffer.readUtf8())
   }
 
+  @Test
+  fun writeCustomNull() {
+    val customTypeAdapters: MutableMap<ScalarType, CustomTypeAdapter<*>> = HashMap()
+    val scalarType = MockCustomScalarType(CustomTypeValue.GraphQLNumber::class, "com.apollographql.apollo.api.CustomTypeValue.GraphQLNull")
+    customTypeAdapters[scalarType] = object : MockCustomTypeAdapter() {
+      override fun encode(value: Any?): CustomTypeValue<*> {
+        return CustomTypeValue.GraphQLNull
+      }
+    }
+    val inputFieldJsonWriter = InputFieldJsonWriter(jsonWriter, ScalarTypeAdapters(customTypeAdapters))
+    inputFieldJsonWriter.writeCustom("someField", scalarType, null)
+    assertEquals("{\"someField\":null", jsonBuffer.readUtf8())
+  }
+
   @Test
   fun writeCustomJsonObject() {
     val value = mapOf(

apollo-integration/src/test/fixtures/ApolloServerInterceptorFileUploadTest/expectedOperationsPartBodyMultiple.json

@@ -1 +1 @@
-{"operationName":"MultipleUpload","variables":{"files":["image/jpg","image/png"]},"query":"mutation MultipleUpload($files: [Upload!]!) { multipleUpload(files: $files) { __typename id path filename mimetype } }"}
+{"operationName":"MultipleUpload","variables":{"files":[null,null]},"query":"mutation MultipleUpload($files: [Upload!]!) { multipleUpload(files: $files) { __typename id path filename mimetype } }"}

apollo-integration/src/test/fixtures/ApolloServerInterceptorFileUploadTest/expectedOperationsPartBodyNested.json

@@ -1 +1 @@
-{"operationName":"NestedUpload","variables":{"topFile":"image/png","topFileList":["image/jpg","plain/txt"],"nested":{"recursiveNested":[{"file":"plain/txt","fileList":["image/jpg","image/png"]},{"file":"image/jpg","fileList":["plain/txt","image/png"]}],"file":"image/png","fileList":["plain/txt","image/jpg"]}},"query":"mutation NestedUpload($topFile: Upload, $topFileList: [Upload], $nested: NestedObject) { nestedUpload(topFile: $topFile, topFileList: $topFileList, nested: $nested) }"}
+{"operationName":"NestedUpload","variables":{"topFile":null,"topFileList":[null,null],"nested":{"recursiveNested":[{"file":null,"fileList":[null,null]},{"file":null,"fileList":[null,null]}],"file":null,"fileList":[null,null]}},"query":"mutation NestedUpload($topFile: Upload, $topFileList: [Upload], $nested: NestedObject) { nestedUpload(topFile: $topFile, topFileList: $topFileList, nested: $nested) }"}

apollo-integration/src/test/fixtures/ApolloServerInterceptorFileUploadTest/expectedOperationsPartBodySingle.json

@@ -1 +1 @@
-{"operationName":"SingleUpload","variables":{"file":"image/jpg"},"query":"mutation SingleUpload($file: Upload!) { singleUpload(file: $file) { __typename id path filename mimetype } }"}
+{"operationName":"SingleUpload","variables":{"file":null},"query":"mutation SingleUpload($file: Upload!) { singleUpload(file: $file) { __typename id path filename mimetype } }"}

apollo-integration/src/test/fixtures/ApolloServerInterceptorFileUploadTest/expectedOperationsPartBodyTwice.json

@@ -1 +1 @@
-{"operationName":"SingleUploadTwice","variables":{"file1":"image/jpg","file2":"image/png"},"query":"mutation SingleUploadTwice($file1: Upload!, $file2: Upload!) { file1: singleUpload(file: $file1) { __typename id path filename mimetype } file2: singleUpload(file: $file2) { __typename id path filename mimetype } }"}
+{"operationName":"SingleUploadTwice","variables":{"file1":null,"file2":null},"query":"mutation SingleUploadTwice($file1: Upload!, $file2: Upload!) { file1: singleUpload(file: $file1) { __typename id path filename mimetype } file2: singleUpload(file: $file2) { __typename id path filename mimetype } }"}