Facing problem with JSON parsing in swift - swift

Question

My REST returns following Array, and only one item.
{
"Table1": [
{
"Id": 1,
"ClauseNo": "2-111",
"Title": "Testing Title",
"URL": "http://www.google.com",
}
]
}
I'm trying to use the Codable as following:
struct Clause: Codable {
var Id: Int
var ClauseNo: String
var Title: String
var URL: String
}
What I'm doing wrong with following code?
func parse(json: Data) -> Clause {
var clause: Clause?
if let jsonClause = try? JSONDecoder().decode([Clause].self, from: json) {
clause = jsonClause
}
return clause!
}
As I mentioned above, I only have 1 item not more than that.

Answer 1

This is very common mistake, you are ignoring the root object
struct Root : Decodable {
private enum CodingKeys : String, CodingKey { case table1 = "Table1" }
let table1 : [Clause]
}
struct Clause: Decodable {
private enum CodingKeys : String, CodingKey { case id = "Id", clauseNo = "ClauseNo", title = "Title", url = "URL" }
let id: Int
let clauseNo: String
let title: String
let url: URL
}
...
func parse(json: Data) -> Clause? {
do {
let result = try JSONDecoder().decode(Root.self, from: json)
return result.table1.first
} catch { print(error) }
return nil
}
Side note: Your code crashes reliably if an error occurs

Answer 2

I tend to handle these scenarios like this:
struct Table1 : Codable {
var clauses: [Clause]
struct Clause: Codable {
let Id: Int // variable names should start with a lowercase
let ClauseNo: String // letter :)
let Title: String
let URL: String
}
}
And then when you're decoding you end up with a table from which you want the first element, something like:
if let jsonTable = try? JSONDecoder().decode(Table1.self, from: json) {
clause = jsonTable.clauses[0]
}