feature: Add support for field casing strategy to code gen (#3171)

Co-authored-by: Calvin Cestari <[email protected]>
Co-authored-by: Anthony Miller <[email protected]>

Sources/ApolloCodegenLib/ApolloCodegenConfiguration.swift

@@ -651,53 +651,96 @@ public struct ApolloCodegenConfiguration: Codable, Equatable {
     case exclude
   }
 
-  /// ``CaseConversionStrategy`` is used to specify the strategy used to convert the casing of
-  /// GraphQL schema values into generated Swift code.
-  public enum CaseConversionStrategy: String, Codable, Equatable {
-    /// Generates swift code using the exact name provided in the GraphQL schema
-    /// performing no conversion.
-    case none
-    /// Convert to lower camel case from `snake_case`, `UpperCamelCase`, or `UPPERCASE`.
-    case camelCase
-  }
-
   /// ``ConversionStrategies`` configures rules for how to convert the names of values from the
   /// schema in generated code.
   public struct ConversionStrategies: Codable, Equatable {
+
+    /// ``ApolloCodegenConfiguration/ConversionStrategies/EnumCase`` is used to specify the strategy
+    /// used to convert the casing of enum cases in a GraphQL schema into generated Swift code.
+    public enum EnumCases: String, Codable, Equatable {
+      /// Generates swift code using the exact name provided in the GraphQL schema
+      /// performing no conversion.
+      case none
+      /// Convert to lower camel case from `snake_case`, `UpperCamelCase`, or `UPPERCASE`.
+      case camelCase
+    }
+
+    /// ``ApolloCodegenConfiguration/ConversionStrategies/FieldAccessors`` is used to specify the
+    /// strategy used to convert the casing of fields on GraphQL selection sets into field accessors
+    /// on the response models in generated Swift code.
+    public enum FieldAccessors: String, Codable, Equatable {
+      /// This conversion strategy will:
+      /// - Lowercase the first letter of all fields.
+      /// - Convert field names that are all `UPPERCASE` to all `lowercase`.
+      case idiomatic
+      /// This conversion strategy will:
+      /// - Convert to `lowerCamelCase` from `snake_case`, or `UpperCamelCase`.
+      /// - Convert field names that are all `UPPERCASE` to all `lowercase`.
+      case camelCase
+    }
+
     /// Determines how the names of enum cases in the GraphQL schema will be converted into
     /// cases on the generated Swift enums.
     /// Defaultss to ``ApolloCodegenConfiguration/CaseConversionStrategy/camelCase``
-    public let enumCases: CaseConversionStrategy
+    public let enumCases: EnumCases
+
+    /// Determines how the names of fields in the GraphQL schema will be converted into
+    /// properties in the generated Swift code.
+    /// Defaults to ``ApolloCodegenConfiguration/CaseConversionStrategy/camelCase``
+    public let fieldAccessors: FieldAccessors
 
     /// Default property values
     public struct Default {
-      public static let enumCases: CaseConversionStrategy = .camelCase
+      public static let enumCases: EnumCases = .camelCase
+      public static let fieldAccessors: FieldAccessors = .idiomatic
     }
-
-    public init(enumCases: CaseConversionStrategy = Default.enumCases) {
+
+    public init(
+      enumCases: EnumCases = Default.enumCases,
+      fieldAccessors: FieldAccessors = Default.fieldAccessors
+    ) {
       self.enumCases = enumCases
+      self.fieldAccessors = fieldAccessors
     }
 
     // MARK: Codable
 
     public enum CodingKeys: CodingKey {
       case enumCases
+      case fieldAccessors
     }
 
     public init(from decoder: Decoder) throws {
       let values = try decoder.container(keyedBy: CodingKeys.self)
       guard values.allKeys.first != nil else {
         throw DecodingError.typeMismatch(Self.self, DecodingError.Context.init(
           codingPath: values.codingPath,
-          debugDescription: "Invalid number of keys found, expected one.",
+          debugDescription: "Invalid value found.",
           underlyingError: nil
         ))
       }
 
-      enumCases = try values.decodeIfPresent(
+      if let deprecatedEnumCase = try? values.decodeIfPresent(
         CaseConversionStrategy.self,
         forKey: .enumCases
-      ) ?? Default.enumCases
+      ) {
+        switch deprecatedEnumCase {
+        case .none:
+          enumCases = .none
+        case .camelCase:
+          enumCases = .camelCase
+        }
+      } else {
+        enumCases = try values.decodeIfPresent(
+          EnumCases.self,
+          forKey: .enumCases
+        ) ?? Default.enumCases
+      }
+
+      fieldAccessors = try values.decodeIfPresent(
+        FieldAccessors.self,
+        forKey: .fieldAccessors
+      ) ?? Default.fieldAccessors
     }
   }
 
@@ -1396,6 +1439,34 @@ extension ApolloCodegenConfiguration.OutputOptions {
   }
 }
 
+extension ApolloCodegenConfiguration.ConversionStrategies {
+
+  @available(*, deprecated, renamed: "init(enumCases:fieldAccessors:)")
+  public init(
+    enumCases: CaseConversionStrategy
+  ) {
+    switch enumCases {
+    case .none:
+      self.enumCases = .none
+    case .camelCase:
+      self.enumCases = .camelCase
+    }
+    self.fieldAccessors = Default.fieldAccessors
+  }
+
+  /// ``CaseConversionStrategy`` is used to specify the strategy used to convert the casing of
+  /// GraphQL schema values into generated Swift code.
+  @available(*, deprecated, message: "Use EnumCaseConversionStrategy instead.")
+    public enum CaseConversionStrategy: String, Codable, Equatable {
+      /// Generates swift code using the exact name provided in the GraphQL schema
+      /// performing no conversion.
+      case none
+      /// Convert to lower camel case from `snake_case`, `UpperCamelCase`, or `UPPERCASE`.
+      case camelCase
+  }
+
+}
+
 private struct AnyCodingKey: CodingKey {
   var stringValue: String
 

Sources/ApolloCodegenLib/Templates/InputObjectTemplate.swift

@@ -92,7 +92,7 @@ struct InputObjectTemplate: TemplateRenderer {
   ) -> TemplateString {
     TemplateString("""
     \(fields.map({
-      "\($1.name.asFieldPropertyName): \($1.renderInputValueType(includeDefault: true, config: config.config))"
+      "\($1.name.renderAsFieldPropertyName(config: config.config)): \($1.renderInputValueType(includeDefault: true, config: config.config))"
     }), separator: ",\n")
     """)
   }
@@ -101,7 +101,7 @@ struct InputObjectTemplate: TemplateRenderer {
     _ fields: GraphQLInputFieldDictionary
   ) -> TemplateString {
     TemplateString("""
-    \(fields.map({ "\"\($1.name)\": \($1.name.asFieldPropertyName)" }), separator: ",\n")
+    \(fields.map({ "\"\($1.name)\": \($1.name.renderAsFieldPropertyName(config: config.config))" }), separator: ",\n")
     """)
   }
 
@@ -110,7 +110,7 @@ struct InputObjectTemplate: TemplateRenderer {
     \(documentation: field.documentation, config: config)
     \(deprecationReason: field.deprecationReason, config: config)
     \(accessControlModifier(for: .member))\
-    var \(field.name.asFieldPropertyName): \(field.renderInputValueType(config: config.config)) {
+    var \(field.name.renderAsFieldPropertyName(config: config.config)): \(field.renderInputValueType(config: config.config)) {
       get { __data["\(field.name)"] }
       set { __data["\(field.name)"] = newValue }
     }

Sources/ApolloCodegenLib/Templates/RenderingHelpers/GraphQLEnumValue+Rendered.swift

@@ -19,27 +19,8 @@ extension GraphQLEnumValue.Name {
       return value.asEnumCaseName
 
     case (.swiftEnumCase, .camelCase):
-      return convertToCamelCase(value).asEnumCaseName
+      return value.convertToCamelCase().asEnumCaseName
     }
   }
 
-  /// Convert to `camelCase` from a number of different `snake_case` variants.
-  ///
-  /// All inner `_` characters will be removed, each 'word' will be capitalized, returning a final
-  /// firstLowercased string while preserving original leading and trailing `_` characters.
-  private func convertToCamelCase(_ value: String) -> String {
-    guard value.firstIndex(of: "_") != nil else {
-      if value.firstIndex(where: { $0.isLowercase }) != nil {
-        return value.firstLowercased
-      } else {
-        return value.lowercased()
-      }
-    }
-
-    return value.components(separatedBy: "_")
-      .map({ $0.isEmpty ? "_" : $0.capitalized })
-      .joined()
-      .firstLowercased
-  }
-
 }

Sources/ApolloCodegenLib/Templates/RenderingHelpers/OperationTemplateRenderer.swift

@@ -13,7 +13,7 @@ extension OperationTemplateRenderer {
     return """
     \(`init`)(\(list: variables.map(VariableParameter))) {
       \(variables.map {
-        let name = $0.name.asFieldPropertyName
+        let name = $0.name.renderAsFieldPropertyName(config: config.config)
         return "self.\(name) = \(name)"
       }, separator: "\n")
     }
@@ -24,15 +24,15 @@ extension OperationTemplateRenderer {
     _ variables: [CompilationResult.VariableDefinition]
   ) -> TemplateString {
     """
-    \(variables.map { "public var \($0.name.asFieldPropertyName): \($0.type.rendered(as: .inputValue, config: config.config))"}, separator: "\n")
+    \(variables.map { "public var \($0.name.renderAsFieldPropertyName(config: config.config)): \($0.type.rendered(as: .inputValue, config: config.config))"}, separator: "\n")
     """
   }
 
   func VariableParameter(
     _ variable: CompilationResult.VariableDefinition
   ) -> TemplateString {
       """
-      \(variable.name.asFieldPropertyName): \(variable.type.rendered(as: .inputValue, config: config.config))\
+      \(variable.name.renderAsFieldPropertyName(config: config.config)): \(variable.type.rendered(as: .inputValue, config: config.config))\
       \(if: variable.defaultValue != nil, " = " + variable.renderVariableDefaultValue(config: config.config))
       """
   }
@@ -46,7 +46,7 @@ extension OperationTemplateRenderer {
     }
 
     return """
-      public var __variables: \(if: !graphQLOperation, "GraphQLOperation.")Variables? { [\(list: variables.map { "\"\($0.name)\": \($0.name.asFieldPropertyName)"})] }
+      public var __variables: \(if: !graphQLOperation, "GraphQLOperation.")Variables? { [\(list: variables.map { "\"\($0.name)\": \($0.name.renderAsFieldPropertyName(config: config.config))"})] }
       """
   }
 

Sources/ApolloCodegenLib/Templates/RenderingHelpers/String+SwiftNameEscaping.swift

@@ -2,12 +2,6 @@ import Foundation
 
 
 extension String {
-  /// Renders the string as the property name for a field accessor on a generated `SelectionSet`.
-  /// This escapes the names of properties that would conflict with Swift reserved keywords.
-  var asFieldPropertyName: String {
-    let str = self.isAllUppercased ? self.lowercased() : self.firstLowercased
-    return str.escapeIf(in: SwiftKeywords.FieldAccessorNamesToEscape)
-  }
 
   var asEnumCaseName: String {
     escapeIf(in: SwiftKeywords.FieldAccessorNamesToEscape)
@@ -40,6 +34,43 @@ extension String {
   private func escapeIf(in set: Set<String>) -> String {
     set.contains(self) ? "`\(self)`" : self
   }
+
+  /// Renders the string as the property name for a field accessor on a generated `SelectionSet`.
+  /// This escapes the names of properties that would conflict with Swift reserved keywords.
+  func renderAsFieldPropertyName(
+    config: ApolloCodegenConfiguration
+  ) -> String {
+    var propertyName = self
+
+    switch config.options.conversionStrategies.fieldAccessors {
+    case .camelCase:
+      propertyName = propertyName.convertToCamelCase()
+    case .idiomatic:
+      break
+    }
+
+    propertyName = propertyName.isAllUppercased ? propertyName.lowercased() : propertyName.firstLowercased
+    return propertyName.escapeIf(in: SwiftKeywords.FieldAccessorNamesToEscape)
+  }
+
+  /// Convert to `camelCase` from a number of different `snake_case` variants.
+  ///
+  /// All inner `_` characters will be removed, each 'word' will be capitalized, returning a final
+  /// firstLowercased string while preserving original leading and trailing `_` characters.
+  func convertToCamelCase() -> String {
+    guard self.firstIndex(of: "_") != nil else {
+      if self.firstIndex(where: { $0.isLowercase }) != nil {
+        return self.firstLowercased
+      } else {
+        return self.lowercased()
+      }
+    }
+
+    return self.components(separatedBy: "_")
+      .map({ $0.isEmpty ? "_" : $0.capitalized })
+      .joined()
+      .firstLowercased
+  }
 }
 
 enum SwiftKeywords {

Sources/ApolloCodegenLib/Templates/SelectionSetTemplate.swift

@@ -309,7 +309,7 @@ struct SelectionSetTemplate {
     return """
     \(documentation: field.underlyingField.documentation, config: config)
     \(deprecationReason: field.underlyingField.deprecationReason, config: config)
-    \(renderAccessControl())var \(field.responseKey.asFieldPropertyName): \
+    \(renderAccessControl())var \(field.responseKey.renderAsFieldPropertyName(config: config.config)): \
     \(typeName(for: field, forceOptional: field.isConditionallyIncluded(in: scope))) {\
     \(if: isMutable,
       """
@@ -443,7 +443,7 @@ struct SelectionSetTemplate {
   ) -> TemplateString {
     let isOptional: Bool = field.type.isNullable || field.isConditionallyIncluded(in: scope)
     return """
-    \(field.responseKey.asFieldPropertyName): \(typeName(for: field, forceOptional: isOptional))\
+    \(field.responseKey.renderAsFieldPropertyName(config: config.config)): \(typeName(for: field, forceOptional: isOptional))\
     \(if: isOptional, " = nil")
     """
   }
@@ -475,7 +475,7 @@ struct SelectionSetTemplate {
     }()
 
     return """
-    "\(field.responseKey)": \(field.responseKey.asFieldPropertyName)\
+    "\(field.responseKey)": \(field.responseKey.renderAsFieldPropertyName(config: config.config))\
     \(if: isEntityField, "._fieldData")
     """
   }

Tests/ApolloCodegenTests/ApolloCodegenConfigurationCodableTests.swift

@@ -45,7 +45,10 @@ class ApolloCodegenConfigurationCodableTests: XCTestCase {
           schemaDocumentation: .exclude,
           cocoapodsCompatibleImportStatements: true,
           warningsOnDeprecatedUsage: .exclude,
-          conversionStrategies:.init(enumCases: .none),
+          conversionStrategies:.init(
+            enumCases: .none,
+            fieldAccessors: .camelCase
+          ),
           pruneGeneratedFiles: false
         ),
         experimentalFeatures: .init(
@@ -91,7 +94,8 @@ class ApolloCodegenConfigurationCodableTests: XCTestCase {
           ],
           "cocoapodsCompatibleImportStatements" : true,
           "conversionStrategies" : {
-            "enumCases" : "none"
+            "enumCases" : "none",
+            "fieldAccessors" : "camelCase"
           },
           "deprecatedEnumCases" : "exclude",
           "operationDocumentFormat" : [

Tests/ApolloCodegenTests/CodeGeneration/Templates/EnumTemplateTests.swift

@@ -176,7 +176,7 @@ class EnumTemplateTests: XCTestCase {
     expect(actual).to(equalLineByLine(expected))
   }
 
-  func test_render_givenOption_caseConversionStrategy_none_generatesSwiftEnumValues_respectingSchemaValueCasing() throws {
+  func test_render_givenOption_caseConversionStrategy_default_generatesSwiftEnumValues_respectingSchemaValueCasing() throws {
     // given
     buildSubject(
       name: "casedEnum",

Tests/ApolloCodegenTests/CodeGeneration/Templates/OperationDefinition_VariableDefinition_Tests.swift

@@ -483,7 +483,7 @@ class OperationDefinition_VariableDefinition_Tests: XCTestCase {
     expect(actual).to(equalLineByLine(expected))
   }
 
-  func test__renderOperationVariableParameter__givenEnumCaseConversion_none_givenEnumField_withDefaultValue__generatesCorrectParametersWithInitializer() throws {
+  func test__renderOperationVariableParameter__givenEnumCaseConversion_default_givenEnumField_withDefaultValue__generatesCorrectParametersWithInitializer() throws {
     // given
     let tests: [(variable: CompilationResult.VariableDefinition, expected: String)] = [
       (