SWIFT-921 Implement extended json decoder methods (#27)

Author: nspektor

Sources/BSON/ExtendedJSONDecoder.swift

@@ -8,9 +8,7 @@ public class ExtendedJSONDecoder {
     }()
 
     /// Initialize an `ExtendedJSONDecoder`.
-    public init() {
-        fatalError("unimplemented")
-    }
+    public init() {}
 
     /// Decodes an instance of the requested type `T` from the provided extended JSON data.
     /// - SeeAlso: https://docs.mongodb.com/manual/reference/mongodb-extended-json/
@@ -21,10 +19,14 @@ public class ExtendedJSONDecoder {
     /// - Returns: Decoded representation of the JSON input as an instance of `T`.
     /// - Throws: `DecodingError` if the JSON data is corrupt or if any value throws an error during decoding.
     public func decode<T: Decodable>(_ type: T.Type, from data: Data) throws -> T {
+        // Data --> JSON --> BSON --> T
         // Takes in JSON as `Data` encoded with `.utf8` and runs it through a `JSONDecoder` to get an
-        // instance of the `JSON` enum. Then a `BSON` enum instance is created via the `JSON`.
+        // instance of the `JSON` enum.
+        let wrappedData = "[".utf8 + data + "]".utf8
+        let json = try JSONDecoder().decode([JSON].self, from: wrappedData)[0]
+        // Then a `BSON` enum instance is created via the `JSON`.
+        let bson = try BSON(fromExtJSON: json, keyPath: [])
         // The `BSON` is then passed through a `BSONDecoder` where it is outputted as a `T`
-        // Data --> JSON --> BSON --> T
-        fatalError("unimplemented")
+        return try BSONDecoder().decode(T.self, fromBSON: bson)
     }
 }

Tests/BSONTests/ExtendedJSONConversionTests.swift

@@ -14,6 +14,19 @@ open class ExtendedJSONConversionTestCase: BSONTestCase {
         expect(document.documentValue!["extra"]).to(equal(.int32(1)))
     }
 
+    func testExtendedJSONDecoder() throws {
+        struct Foo: Decodable, Equatable {
+            let x: Bool
+            let y: Int
+            let z: BSONRegularExpression
+        }
+        let regexStr = "{\"$regularExpression\": {\"pattern\": \"p\", \"options\": \"i\"}}"
+        let regexObj = BSONRegularExpression(pattern: "p", options: "i")
+        let data = "{ \"x\": true, \"y\": { \"$numberInt\": \"5\" }, \"z\": \(regexStr) }".data(using: .utf8)!
+        let decoder = ExtendedJSONDecoder()
+        expect(try decoder.decode(Foo.self, from: data)).to(equal(Foo(x: true, y: 5, z: regexObj)))
+    }
+
     func testObjectId() throws {
         let oid = "5F07445CFBBBBBBBBBFAAAAA"