From b44d0b4fff4192f67b4ab5c5c737620674c39421 Mon Sep 17 00:00:00 2001
From: Anthony Miller <anthonymdev@gmail.com>
Date: Thu, 31 Aug 2023 13:10:46 -0700
Subject: [PATCH] Remove stripping of null values from Selection Set models
 (apollographql/apollo-ios-dev#25)

---
 Sources/Apollo/ApolloStore.swift               |  1 -
 Sources/Apollo/GraphQLSelectionSetMapper.swift | 13 +++++++++----
 Sources/ApolloAPI/DataDict.swift               |  4 +---
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/Sources/Apollo/ApolloStore.swift b/Sources/Apollo/ApolloStore.swift
index e2ad5862e2..cc4ea7c3cf 100644
--- a/Sources/Apollo/ApolloStore.swift
+++ b/Sources/Apollo/ApolloStore.swift
@@ -278,7 +278,6 @@ public class ApolloStore {
         withKey: key,
         variables: variables,
         accumulator: GraphQLSelectionSetMapper<SelectionSet>(
-          stripNullValues: false,
           handleMissingValues: .allowForOptionalFields
         )
       )
diff --git a/Sources/Apollo/GraphQLSelectionSetMapper.swift b/Sources/Apollo/GraphQLSelectionSetMapper.swift
index 4583674495..d67907574e 100644
--- a/Sources/Apollo/GraphQLSelectionSetMapper.swift
+++ b/Sources/Apollo/GraphQLSelectionSetMapper.swift
@@ -7,7 +7,6 @@ final class GraphQLSelectionSetMapper<T: SelectionSet>: GraphQLResultAccumulator
 
   let requiresCacheKeyComputation: Bool = false
 
-  let stripNullValues: Bool
   let handleMissingValues: HandleMissingValues
 
   enum HandleMissingValues {
@@ -19,10 +18,8 @@ final class GraphQLSelectionSetMapper<T: SelectionSet>: GraphQLResultAccumulator
   }
 
   init(
-    stripNullValues: Bool = true,
     handleMissingValues: HandleMissingValues = .disallow
   ) {
-    self.stripNullValues = stripNullValues
     self.handleMissingValues = handleMissingValues
   }
 
@@ -48,7 +45,7 @@ final class GraphQLSelectionSetMapper<T: SelectionSet>: GraphQLResultAccumulator
   }
 
   func acceptNullValue(info: FieldExecutionInfo) -> AnyHashable? {
-    return stripNullValues ? nil : Optional<AnyHashable>.none
+    return DataDict.NullValue
   }
 
   func acceptMissingValue(info: FieldExecutionInfo) throws -> AnyHashable? {
@@ -89,3 +86,11 @@ final class GraphQLSelectionSetMapper<T: SelectionSet>: GraphQLResultAccumulator
     return T.init(_dataDict: rootValue)
   }
 }
+
+// MARK: - Null Value Definition
+extension DataDict {
+  /// A common value used to represent a null value in a `DataDict`.
+  ///
+  /// This value can be cast to `NSNull` and will bridge automatically.
+  static let NullValue = AnyHashable(Optional<AnyHashable>.none)
+}
diff --git a/Sources/ApolloAPI/DataDict.swift b/Sources/ApolloAPI/DataDict.swift
index c8651384b6..d5e458df26 100644
--- a/Sources/ApolloAPI/DataDict.swift
+++ b/Sources/ApolloAPI/DataDict.swift
@@ -126,9 +126,7 @@ public struct DataDict: Hashable {
   }
 }
 
-
-
-// MARK: Value Conversion Helpers
+// MARK: - Value Conversion Helpers
 
 public protocol SelectionSetEntityValue {
   /// - Warning: This function is not supported for external use.