Error extensions support

Sources/GraphQL/Error/GraphQLError.swift

@@ -9,6 +9,7 @@ public struct GraphQLError : Error, Codable {
         case message
         case locations
         case path
+        case extensions
     }
 
     /**
@@ -29,6 +30,18 @@ public struct GraphQLError : Error, Codable {
      * Appears in the result of `description`.
      */
     public let locations: [SourceLocation]
+
+    /**
+     * A dictionary containing original error reflection
+     * to supply additional data from error extensions.
+     *
+     * Will reflect only Codable objects.
+     *
+     * For more information about supported types look at `AnyCodable` - `init(from:)`
+     *
+     * Appears in the result of `description`.
+     */
+    public let extensions: [String: AnyCodable]?
 
     /**
      * An array describing the index path into the execution response which
@@ -92,6 +105,7 @@ public struct GraphQLError : Error, Codable {
 
         self.path = path
         self.originalError = originalError
+        self.extensions = originalError?.reflection
     }
 
     public init(
@@ -106,6 +120,7 @@ public struct GraphQLError : Error, Codable {
         self.source = nil
         self.positions = []
         self.originalError = nil
+        self.extensions = nil
     }
 
     public init(_ error: Error) {
@@ -120,6 +135,7 @@ public struct GraphQLError : Error, Codable {
         message = try container.decode(String.self, forKey: .message)
         locations = try container.decode([SourceLocation]?.self, forKey: .locations) ?? []
         path = try container.decode(IndexPath.self, forKey: .path)
+        extensions = try container.decodeIfPresent([String: AnyCodable].self, forKey: .extensions)
     }
 
     public func encode(to encoder: Encoder) throws {
@@ -132,6 +148,10 @@ public struct GraphQLError : Error, Codable {
         }
 
         try container.encode(path, forKey: .path)
+
+        if let extensions = extensions {
+            try container.encode(extensions, forKey: .extensions)
+        }
     }
 }
 

Sources/GraphQL/Extensions/Codable+Extensions.swift

@@ -9,3 +9,38 @@ public class AnyEncodable : Encodable {
         return try self.encodable.encode(to: encoder)
     }
 }
+
+public class AnyCodable : Codable {
+    private let codable: Codable
+
+    public init(_ codable: Codable) {
+        self.codable = codable
+    }
+
+    public func encode(to encoder: Encoder) throws {
+        return try self.codable.encode(to: encoder)
+    }
+
+    required public init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        if container.decodeNil() {
+            self.codable = "Null"
+        } else if let bool = try? container.decode(Bool.self) {
+            self.codable = bool
+        } else if let int = try? container.decode(Int.self) {
+            self.codable = int
+        } else if let uint = try? container.decode(UInt.self) {
+            self.codable = uint
+        } else if let double = try? container.decode(Double.self) {
+            self.codable = double
+        } else if let string = try? container.decode(String.self) {
+            self.codable = string
+        } else if let array = try? container.decode([AnyCodable].self) {
+            codable = array
+        } else if let dictionary = try? container.decode([String: AnyCodable].self) {
+            codable = dictionary
+        } else {
+            throw DecodingError.dataCorruptedError(in: container, debugDescription: "AnyCodable: can't decode value")
+        }
+    }
+}

Sources/GraphQL/Extensions/Error+Extensions.swift

@@ -0,0 +1,13 @@
+public extension Error {
+    var reflection: [String: AnyCodable] {
+        let errorReflection: Mirror = Mirror(reflecting: self)
+        return Dictionary(uniqueKeysWithValues: errorReflection.children.lazy.map({ (label: String?, value: Any) -> (String, AnyCodable)? in
+            guard let key = label,
+                  let codableValue = value as? Codable else {
+                      return nil
+            }
+
+            return (key, AnyCodable(codableValue))
+        }).compactMap { $0 })
+    }
+}