advanced patterns When Parsing JSON with Optional Fields in Swift 5 - Missing Key Errors
I'm stuck on something that should probably be simple. I'm trying to configure I'm attempting to set up I've been struggling with this for a few days now and could really use some help. I'm currently working on a Swift application where I'm parsing JSON data from a REST API. The JSON response includes several optional fields, and I'm using the `Codable` protocol for deserialization. However, I'm working with a frequent scenario where the absence of these optional fields sometimes leads to unexpected key errors, despite properly declaring the properties as optional in my structs. Here's a simplified version of my JSON response: ```json { "id": 123, "name": "Example Item", "description": "This is an example item.", "category": null, "tags": ["example", "item"] } ``` And here's how I've declared my Swift struct: ```swift struct Item: Codable { let id: Int let name: String let description: String let category: String? let tags: [String]? } ``` When I attempt to decode this JSON with the following code: ```swift let jsonData = ... // Assume this is your JSON data typical code here typical code here let item = try JSONDecoder().decode(Item.self, from: jsonData) ``` I occasionally see the following behavior: ``` behavior: KeyedDecodingContainer.keyNotFound(CodingKeys(stringValue: "category", intValue: nil), DecodingError.Context(codingPath: [], debugDescription: "want to get value for key 'category' because it does not exist.", underlyingError: nil)) ``` I’m confused because I thought that declaring `category` as an optional should prevent these errors if the key is missing. I've also tried adding a default value using the `init(from:)` method to handle missing keys, but that didn’t seem to resolve the scenario either. Is there a specific reason why this might be happening, or is there a better approach to handle optional fields in Swift's `Codable`? Any insights or suggestions would be greatly appreciated! I'm working on a application that needs to handle this. The stack includes Swift and several other technologies. I'd love to hear your thoughts on this. I appreciate any insights! I'm on CentOS using the latest version of Swift. Has anyone dealt with something similar?