parsing nested Array using codable in swift 4 - ios

Question

I am getting many random issues. Mostly like some structure is not decodable not able to understand how to define structure.
Please find the code snipped
var JSON = """
{"variants":{"variant_groups":[{"group_id":"1","name":"Crust","variations":[{"name":"Thin","price":0,"default":1,"id":"1","inStock":1},{"name":"Thick","price":0,"default":0,"id":"2","inStock":1,"isVeg":1},{"name":"Cheese burst","price":100,"default":0,"id":"3","inStock":1,"isVeg":1}]},{"group_id":"2","name":"Size","variations":[{"name":"Small","price":0,"default":1,"id":"10","inStock":1,"isVeg":0},{"name":"Medium","price":100,"default":0,"id":"11","inStock":1,"isVeg":1},{"name":":Large","price":200,"default":0,"id":"12","inStock":1,"isVeg":0}]},{"group_id":"3","name":"Sauce","variations":[{"name":"Manchurian","price":20,"default":0,"id":"20","inStock":1,"isVeg":0},{"name":"Tomato","price":20,"default":0,"id":"21","inStock":1,"isVeg":1},{"name":"Mustard","price":20,"default":0,"id":"22","inStock":1,"isVeg":0}]}],"exclude_list":[[{"group_id":"1","variation_id":"3"},{"group_id":"2","variation_id":"10"}],[{"group_id":"2","variation_id":"10"},{"group_id":"3","variation_id":"22"}]]}}
""".data(using: .utf8)
/*
not sure is this the right way to define Root
*/
struct Root : Codable {
let variants : varientStruct
let exclude_list : exclude_list
}
struct exclude_list : Codable{
let variation_id : String
let group_id : String
}
struct varientStruct: Codable {
let variant_groups = [variant_groups_struct]
}
struct variant_groups_struct : Codable {
let group_id : String
let name :String
let variations: [variationsStruct]
}
struct variationsStruct :Codable {
let name : String
let price : Int
let selected: Int
let id : String
let inStock: Bool
enum CodingKeys : String, CodingKey {
case name
case price
case selected = "default"
case id
case inStock
}
}
}
do {
let data = Data(person.utf8)
let result = try JSONDecoder().decode(Root.self, from: JSON)
print(result)
} catch {
print(error)
}

Answer 1

First of all and once again, please conform to the naming convention:
struct and class names start with a uppercase letter.
Variable and function names start with a lowercase letter.
All variable and struct / class names are camelCased rather than snake_cased.
Second of all, JSON is very easy to read. There are only two collection types (array [] and dictionary {}) and four value types.
Format the JSON string to be able to recognize the structure more conveniently
let jsonString = """
{"variants":{"variant_groups":[{"group_id":"1","name":"Crust","variations":
[{"name":"Thin","price":0,"default":1,"id":"1","inStock":1},
{"name":"Thick","price":0,"default":0,"id":"2","inStock":1,"isVeg":1},
{"name":"Cheese burst","price":100,"default":0,"id":"3","inStock":1,"isVeg":1}]
},{"group_id":"2","name":"Size","variations":
[{"name":"Small","price":0,"default":1,"id":"10","inStock":1,"isVeg":0},
{"name":"Medium","price":100,"default":0,"id":"11","inStock":1,"isVeg":1},
{"name":":Large","price":200,"default":0,"id":"12","inStock":1,"isVeg":0}]
},{"group_id":"3","name":"Sauce","variations":
[{"name":"Manchurian","price":20,"default":0,"id":"20","inStock":1,"isVeg":0},
{"name":"Tomato","price":20,"default":0,"id":"21","inStock":1,"isVeg":1},
{"name":"Mustard","price":20,"default":0,"id":"22","inStock":1,"isVeg":0}]
}],
"exclude_list":[[{"group_id":"1","variation_id":"3"}, {"group_id":"2","variation_id":"10"}],
[{"group_id":"2","variation_id":"10"},{"group_id":"3","variation_id":"22"}]]
}
}
"""
Then build the structs according to the JSON structure step by step
struct Root : Decodable {
let variants : Variant
}
struct Variant : Decodable {
private enum CodingKeys : String, CodingKey {
case groups = "variant_groups"
case excludeList = "exclude_list"
}
let groups : [VariantGroup]
let excludeList : [[ExcludeList]]
}
struct VariantGroup : Decodable {
private enum CodingKeys : String, CodingKey {
case groupID = "group_id"
case name, variations
}
let groupID : String
let name : String
let variations : [Variation]
}
struct Variation : Decodable {
let name : String
let price : Int
let `default` : Int
let id : String
let inStock : Int
}
struct ExcludeList : Decodable {
private enum CodingKeys : String, CodingKey {
case groupID = "group_id"
case variationID = "variation_id"
}
let groupID : String
let variationID : String
}
Then decode the stuff
do {
let data = Data(jsonString.utf8)
let result = try JSONDecoder().decode(Root.self, from: data)
print(result)
} catch { print(error) }