Field Merging[1/x] Configuration Options

apollo-ios-codegen/Sources/ApolloCodegenLib/ApolloCodegenConfiguration.swift

@@ -466,6 +466,8 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
     public let schemaDocumentation: Composition
     /// Which generated selection sets should include generated initializers.
     public let selectionSetInitializers: SelectionSetInitializers
+    /// Which merged fields and named fragment accessors are generated. Defaults to `.all`.
+    public let fieldMerging: FieldMerging
     /// How to generate the operation documents for your generated operations.
     public let operationDocumentFormat: OperationDocumentFormat
     /// Generate import statements that are compatible with including `Apollo` via Cocoapods.
@@ -513,6 +515,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
       public static let deprecatedEnumCases: Composition = .include
       public static let schemaDocumentation: Composition = .include
       public static let selectionSetInitializers: SelectionSetInitializers = [.localCacheMutations]
+      public static let fieldMerging: FieldMerging = [.all]
       public static let operationDocumentFormat: OperationDocumentFormat = .definition
       public static let cocoapodsCompatibleImportStatements: Bool = false
       public static let warningsOnDeprecatedUsage: Composition = .include
@@ -530,6 +533,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
     ///   - schemaDocumentation: Whether schema documentation is added to the generated files.
     ///   - selectionSetInitializers: Which generated selection sets should include
     ///     generated initializers.
+    ///   - fieldMerging: Which merged fields and named fragment accessors are generated.
     ///   - operationDocumentFormat: How to generate the operation documents for your generated operations.
     ///   - cocoapodsCompatibleImportStatements: Generate import statements that are compatible with
     ///     including `Apollo` via Cocoapods.
@@ -545,6 +549,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
       deprecatedEnumCases: Composition = Default.deprecatedEnumCases,
       schemaDocumentation: Composition = Default.schemaDocumentation,
       selectionSetInitializers: SelectionSetInitializers = Default.selectionSetInitializers,
+      fieldMerging: FieldMerging = Default.fieldMerging,
       operationDocumentFormat: OperationDocumentFormat = Default.operationDocumentFormat,
       cocoapodsCompatibleImportStatements: Bool = Default.cocoapodsCompatibleImportStatements,
       warningsOnDeprecatedUsage: Composition = Default.warningsOnDeprecatedUsage,
@@ -556,6 +561,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
       self.deprecatedEnumCases = deprecatedEnumCases
       self.schemaDocumentation = schemaDocumentation
       self.selectionSetInitializers = selectionSetInitializers
+      self.fieldMerging = fieldMerging
       self.operationDocumentFormat = operationDocumentFormat
       self.cocoapodsCompatibleImportStatements = cocoapodsCompatibleImportStatements
       self.warningsOnDeprecatedUsage = warningsOnDeprecatedUsage
@@ -572,6 +578,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
       case deprecatedEnumCases
       case schemaDocumentation
       case selectionSetInitializers
+      case fieldMerging
       case apqs
       case operationDocumentFormat
       case cocoapodsCompatibleImportStatements
@@ -605,6 +612,11 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
         forKey: .selectionSetInitializers
       ) ?? Default.selectionSetInitializers
 
+      fieldMerging = try values.decodeIfPresent(
+        FieldMerging.self,
+        forKey: .fieldMerging
+      ) ?? Default.fieldMerging
+
       operationDocumentFormat = try values.decodeIfPresent(
         OperationDocumentFormat.self,
         forKey: .operationDocumentFormat
@@ -648,6 +660,7 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
       try container.encode(self.deprecatedEnumCases, forKey: .deprecatedEnumCases)
       try container.encode(self.schemaDocumentation, forKey: .schemaDocumentation)
       try container.encode(self.selectionSetInitializers, forKey: .selectionSetInitializers)
+      try container.encode(self.fieldMerging, forKey: .fieldMerging)
       try container.encode(self.operationDocumentFormat, forKey: .operationDocumentFormat)
       try container.encode(self.cocoapodsCompatibleImportStatements, forKey: .cocoapodsCompatibleImportStatements)
       try container.encode(self.warningsOnDeprecatedUsage, forKey: .warningsOnDeprecatedUsage)
@@ -902,6 +915,43 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
     }
   }
 
+  /// The `FieldMerging` configuration is used to determine what merged fields and named fragment
+  /// accessors are present on the generated selection set models. Field merging generates
+  /// selection set models that are easier to use, but more verbose.
+  ///
+  /// Property accessors are always generated for each field directly included in a selection
+  /// set in the GraphQL definition. In addition, the code generation engine can compute which
+  /// selections from a selection set's parents, sibling inline fragments, and named fragment
+  /// spreads will also be included on the response object, given the selection set's scope.
+  ///
+  /// By default, all possible fields and named fragment accessors are merged into each selection
+  /// set.
+  public struct FieldMerging: OptionSet, Codable, Equatable {
+    /// Merges fields and fragment accessors from the selection set's direct ancestors.
+    public static let ancestors          = FieldMerging(rawValue: 1 << 0)
+
+    /// Merges fields and fragment accessors from sibling inline fragments that match the selection
+    /// set's scope.
+    public static let siblings           = FieldMerging(rawValue: 1 << 1)
+
+    /// Merges fields and fragment accessors from named fragments that have been spread into the
+    /// selection set.
+    public static let namedFragments     = FieldMerging(rawValue: 1 << 2)
+
+    /// Merges all possible fields and fragment accessors from all sources.
+    public static let all: FieldMerging  = [.ancestors, .siblings, .namedFragments]
+
+    /// Disables field merging entirely. Aside from removal of redundant selections, the shape of
+    /// the generated models will directly mirror the GraphQL definition.
+    public static let none: FieldMerging = FieldMerging(rawValue: 0)
+
+    public let rawValue: Int
+
+    public init(rawValue: Int) {
+      self.rawValue = rawValue
+    }
+  }
+
   public struct ExperimentalFeatures: Codable, Equatable {
     /**
      * **EXPERIMENTAL**: If enabled, the generated operations will be transformed using a method
@@ -1332,6 +1382,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
   ///   - schemaDocumentation: Whether schema documentation is added to the generated files.
   ///   - selectionSetInitializers: Which generated selection sets should include
   ///     generated initializers.
+  ///   - fieldMerging: Which merged fields and named fragment accessors are generated.
   ///   - apqs: Whether the generated operations should use Automatic Persisted Queries.
   ///   - cocoapodsCompatibleImportStatements: Generate import statements that are compatible with
   ///     including `Apollo` via Cocoapods.
@@ -1351,6 +1402,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
     deprecatedEnumCases: ApolloCodegenConfiguration.Composition = Default.deprecatedEnumCases,
     schemaDocumentation: ApolloCodegenConfiguration.Composition = Default.schemaDocumentation,
     selectionSetInitializers: ApolloCodegenConfiguration.SelectionSetInitializers = Default.selectionSetInitializers,
+    fieldMerging: ApolloCodegenConfiguration.FieldMerging = Default.fieldMerging,
     apqs: ApolloCodegenConfiguration.APQConfig,
     cocoapodsCompatibleImportStatements: Bool = Default.cocoapodsCompatibleImportStatements,
     warningsOnDeprecatedUsage: ApolloCodegenConfiguration.Composition = Default.warningsOnDeprecatedUsage,
@@ -1362,6 +1414,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
     self.deprecatedEnumCases = deprecatedEnumCases
     self.schemaDocumentation = schemaDocumentation
     self.selectionSetInitializers = selectionSetInitializers
+    self.fieldMerging = fieldMerging
     self.operationDocumentFormat = apqs.operationDocumentFormat
     self.cocoapodsCompatibleImportStatements = cocoapodsCompatibleImportStatements
     self.warningsOnDeprecatedUsage = warningsOnDeprecatedUsage
@@ -1381,6 +1434,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
   ///   - schemaDocumentation: Whether schema documentation is added to the generated files.
   ///   - selectionSetInitializers: Which generated selection sets should include
   ///     generated initializers.
+  ///   - fieldMerging: Which merged fields and named fragment accessors are generated.
   ///   - operationDocumentFormat: How to generate the operation documents for your generated operations.
   ///   - cocoapodsCompatibleImportStatements: Generate import statements that are compatible with
   ///     including `Apollo` via Cocoapods.
@@ -1400,6 +1454,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
     deprecatedEnumCases: ApolloCodegenConfiguration.Composition = Default.deprecatedEnumCases,
     schemaDocumentation: ApolloCodegenConfiguration.Composition = Default.schemaDocumentation,
     selectionSetInitializers: ApolloCodegenConfiguration.SelectionSetInitializers = Default.selectionSetInitializers,
+    fieldMerging: ApolloCodegenConfiguration.FieldMerging = Default.fieldMerging,
     operationDocumentFormat: ApolloCodegenConfiguration.OperationDocumentFormat = Default.operationDocumentFormat,
     cocoapodsCompatibleImportStatements: Bool = Default.cocoapodsCompatibleImportStatements,
     warningsOnDeprecatedUsage: ApolloCodegenConfiguration.Composition = Default.warningsOnDeprecatedUsage,
@@ -1411,6 +1466,7 @@ extension ApolloCodegenConfiguration.OutputOptions {
     self.deprecatedEnumCases = deprecatedEnumCases
     self.schemaDocumentation = schemaDocumentation
     self.selectionSetInitializers = selectionSetInitializers
+    self.fieldMerging = fieldMerging
     self.operationDocumentFormat = operationDocumentFormat
     self.cocoapodsCompatibleImportStatements = cocoapodsCompatibleImportStatements
     self.warningsOnDeprecatedUsage = warningsOnDeprecatedUsage

apollo-ios-codegen/Sources/IR/IR+ComputedSelectionSet.swift

@@ -169,6 +169,7 @@ extension ComputedSelectionSet {
     fileprivate func finalize() -> ComputedSelectionSet {
       let merged = MergedSelections(
         mergedSources: mergedSources,
+        mergingStrategy: .all,
         fields: fields,
         inlineFragments: inlineFragments,
         namedFragments: namedFragments

apollo-ios-codegen/Sources/IR/IR+MergedSelections.swift

@@ -1,20 +1,18 @@
 import Foundation
 import OrderedCollections
 
-/// Represents the selections that merged into a selection set from other selection sets.
-/// This includes all selections from other related `SelectionSet`s on the same entity that match
-/// the selection set's type scope.
+/// Represents the selections that are merged into a selection set from other selection sets,
+/// using the given ``MergingStrategy``. See ``MergingStrategy`` for more information on what is
+/// included in the ``MergedSelections`` for a given strategy.
 ///
-/// Combining the `MergedSelections` with the `DirectSelections` for a `SelectionSet` provides all
-/// selections that are available to be accessed by the selection set.
-///
-/// To get the `MergedSelections` for a `SelectionSet` use a `ComputedSelectionSet`.
-///
-/// Selections in the `mergedSelections` are guaranteed to be selected if this `SelectionSet`'s
+/// Selections in the `MergedSelections` are guaranteed to be selected if this `SelectionSet`'s
 /// `selections` are selected. This means they can be merged into the generated object
 /// representing this `SelectionSet` as field accessors.
+///
+/// To get the ``MergedSelections`` for a ``SelectionSet`` use a ``ComputedSelectionSet/Builder``.
 public struct MergedSelections: Equatable {
   public let mergedSources: OrderedSet<MergedSource>
+  public let mergingStrategy: MergingStrategy
   public let fields: OrderedDictionary<String, Field>
   public let inlineFragments: OrderedDictionary<ScopeCondition, InlineFragmentSpread>
   public let namedFragments: OrderedDictionary<String, NamedFragmentSpread>
@@ -25,6 +23,7 @@ public struct MergedSelections: Equatable {
 
   public static func == (lhs: MergedSelections, rhs: MergedSelections) -> Bool {
     lhs.mergedSources == rhs.mergedSources &&
+    lhs.mergingStrategy == rhs.mergingStrategy &&
     lhs.fields == rhs.fields &&
     lhs.inlineFragments == rhs.inlineFragments &&
     lhs.namedFragments == rhs.namedFragments
@@ -45,6 +44,45 @@ extension MergedSelections {
   }
 }
 
+// MARK: - MergingStrategy
+
+extension MergedSelections {
+  /// The ``MergingStrategy`` is used to determine what merged fields and named fragment
+  /// accessors are merged into the ``MergedSelections``.
+  ///
+  /// ``MergedSelections`` can compute which selections from a selection set's parents, sibling
+  /// inline fragments, and named fragment spreads will also be included on the response object,
+  /// given the selection set's ``SelectionSet/TypeInfo``.
+  public struct MergingStrategy: OptionSet, Equatable {
+    /// Merges fields and fragment accessors from the selection set's direct ancestors.
+    public static let ancestors          = MergingStrategy(rawValue: 1 << 0)
+
+    /// Merges fields and fragment accessors from sibling inline fragments that match the selection
+    /// set's scope.
+    public static let siblings           = MergingStrategy(rawValue: 1 << 1)
+
+    /// Merges fields and fragment accessors from named fragments that have been spread into the
+    /// selection set.
+    public static let namedFragments     = MergingStrategy(rawValue: 1 << 2)
+
+    /// Merges all possible fields and fragment accessors from all sources.
+    ///
+    /// This includes all selections from other related `SelectionSet`s on the same entity that match
+    /// the selection set's type scope.
+    ///
+    /// When using this strategy, combining the ``MergedSelections`` with the ``DirectSelections`` 
+    /// for a ``SelectionSet`` provides all selections that are available to be accessed by the
+    /// selection set.
+    public static let all: MergingStrategy  = [.ancestors, .siblings, .namedFragments]
+
+    public let rawValue: Int
+
+    public init(rawValue: Int) {
+      self.rawValue = rawValue
+    }
+  }
+}
+
 // MARK: - CustomDebugStringConvertible
 
 extension MergedSelections: CustomDebugStringConvertible {