Fix: Correctly decode jsonb to String by stripping version byte (#568)

Author: nikodittmar

Sources/PostgresNIO/New/Data/String+PostgresCodable.swift

@@ -29,6 +29,12 @@ extension String: PostgresDecodable {
         context: PostgresDecodingContext<JSONDecoder>
     ) throws {
         switch (format, type) {
+        case (.binary, .jsonb):
+            // Discard the version byte
+            guard let version = buffer.readInteger(as: UInt8.self), version == 1 else {
+                throw PostgresDecodingError.Code.failure
+            }
+            self = buffer.readString(length: buffer.readableBytes)!
         case (_, .varchar),
              (_, .bpchar),
              (_, .text),

Tests/IntegrationTests/PostgresNIOTests.swift

@@ -930,6 +930,22 @@ final class PostgresNIOTests: XCTestCase {
         }
     }
 
+    func testJSONBDecodeString() {
+        var conn: PostgresConnection?
+        XCTAssertNoThrow(conn = try PostgresConnection.test(on: eventLoop).wait())
+        defer { XCTAssertNoThrow(try conn?.close().wait()) }
+
+        do {
+            var rows: PostgresQueryResult?
+            XCTAssertNoThrow(rows = try conn?.query("select '{\"hello\": \"world\"}'::jsonb as data").wait())
+            
+            var resultString: String?
+            XCTAssertNoThrow(resultString = try rows?.first?.decode(String.self, context: .default))
+
+            XCTAssertEqual(resultString, "{\"hello\": \"world\"}")
+        }
+    }
+
     func testInt4RangeSerialize() async throws {
         let conn: PostgresConnection = try await PostgresConnection.test(on: eventLoop).get()
         self.addTeardownBlock {

Tests/PostgresNIOTests/New/Data/String+PSQLCodableTests.swift

@@ -52,4 +52,15 @@ class String_PSQLCodableTests: XCTestCase {
             XCTAssertEqual($0 as? PostgresDecodingError.Code, .failure)
         }
     }
+
+    func testDecodeFromJSONB() {
+        let json = #"{"hello": "world"}"#
+        var buffer = ByteBuffer()
+        buffer.writeInteger(UInt8(1))
+        buffer.writeString(json)
+
+        var decoded: String?
+        XCTAssertNoThrow(decoded = try String(from: &buffer, type: .jsonb, format: .binary, context: .default))
+        XCTAssertEqual(decoded, json)
+    }
 }