Question 262007 in Flutter Question posted in
The official Flutter documentation can be found here.

Flutter – Decode complex json dart

I am working on a Dart application and trying to decode JSON data, but I’m encountering an error that I can’t seem to resolve.

Error:
Errore: type ‘String’ is not a subtype of type ‘Iterable’ in type cast

Flutter code:

 Map value= await apiRequestMap('/api/Recipes/' + model, {}, UrlRequest.GET, true, false, true);
       String decodeMapOperation = json.encode(value);
       (decodeMapOperation as Iterable<dynamic>) // crash 
           .map((dynamic jsonObject) => print(jsonObject['name']))
           .toList();

Json:

[
    {
        "id": 2,
        "name": "salsa bolognese",
        "tool": "",
        "description": "",
        "link": "",
        "picture": "http://207.154.221.255:8600/pictures/recipes/Salsa Bolognese.jpg",
        "phases": [
            {
                "Set_Rpm1_Utensile": "0",
                "Set_Rpm2_Utensile": "0",
                "On_Rpm_Utensile": "0",
                "Off_Rpm_Utensile": "0",
                "Tempo_Rpm_Utensile": "0",
                "Set_Vuoto": "0",
                "On_Vuoto": "0",
                "Off_Vuoto": "0",
                "Tempo_Vuoto": "0",
                "Set_Pressione_In": "0",
                "Set_Pressione_Out": "0",
                "Spatola_On": "false",
                "N_Rotazioni_Spatola": "0",
                "Pausa_Spatola": "0",
                "Set_Caldo": "0",
                "Set_Vapore_Diretto": "0",
                "On_Caldo": "0",
                "Off_Caldo": "0",
                "Tempo_Caldo": "0",
                "Set_Freddo": "0",
                "Set_Gelida": "0",
                "On_Freddo": "0",
                "Off_Freddo": "0",
                "Tempo_Freddo": "0"
            }
        ],
        "time": 12,
        "instructions": [
            {
                "id": 1,
                "content": "Inserire tutti gli ingredienti nel Qbo",
                "order": 1,
                "recipeId": 2
            },
            {
                "id": 2,
                "content": "Chiudere il coperchio",
                "order": 2,
                "recipeId": 2
            },
            {
                "id": 3,
                "content": "Inclinare la vasca a livello 2 e avviare il processo",
                "order": 3,
                "recipeId": 2
            },
            {
                "id": 4,
                "content": "Cucinare la salsa in pressione (fase 2 e 3)",
                "order": 4,
                "recipeId": 2
            },
            {
                "id": 5,
                "content": "Evaporare la parte di liquido in eccesso (fase 4)",
                "order": 5,
                "recipeId": 2
            },
            {
                "id": 6,
                "content": "Raddrizzare la vasca e ripristinare la pressione aprendo la tramoggia",
                "order": 6,
                "recipeId": 2
            },
            {
                "id": 7,
                "content": "Scaricare il prodotto",
                "order": 7,
                "recipeId": 2
            }
        ],
        "ingredients": [
            {
                "id": 1,
                "name": "MACINATO DI BOVINO",
                "quantity": "650 gr",
                "recipeId": 2
            },
            {
                "id": 2,
                "name": "MACINATO DI SUINO",
                "quantity": "450 gr",
                "recipeId": 2
            },
            {
                "id": 3,
                "name": "PANCETTA MACINATA",
                "quantity": "450 gr",
                "recipeId": 2
            },
            {
                "id": 4,
                "name": "SOFFRITTO",
                "quantity": "600 gr",
                "recipeId": 2
            },
            {
                "id": 5,
                "name": "TRIPLO CONCENTRATO DI POMODORO",
                "quantity": "225 gr",
                "recipeId": 2
            },
            {
                "id": 6,
                "name": "VINO BIANCO",
                "quantity": "100 gr",
                "recipeId": 2
            },
            {
                "id": 7,
                "name": "SALE",
                "quantity": "12 gr",
                "recipeId": 2
            },
            {
                "id": 8,
                "name": "PEPE",
                "quantity": "3 gr",
                "recipeId": 2
            },
            {
                "id": 9,
                "name": "ALLORO 1 FOGLIA",
                "quantity": "1",
                "recipeId": 2
            },
            {
                "id": 10,
                "name": "NOCE MOSCATA",
                "quantity": "1",
                "recipeId": 2
            }
        ],
        "updatedAt": "2023-10-09T14:39:18.661132Z"
    }
]
Tags:

2

Answers


  1. 0

    from line

    String decodeMapOperation = json.encode(value); // You made the result to string
// So that's the one making it crash after going to type cast it as iterable
// So it should be decode not encode
 String decodeMapOperation = json.decode(value); // or jsonDecode(value);  

Note: to avoid result as string try to identify the result to like this 

e.g. 
final response = await apiRequestMap('/api/Recipes/' + model, {}, UrlRequest.GET, true, false, true);
 // sample as return data
if(response is String){
 // try to print that the result was string
}else{
 // If not then it's all good
}
    Login or Signup to reply.
  2. 0

    Use json.decode instead

    If value is a json stringified, after you decode it would not be a string, so do not type it as String

    final decodeMapOperation = json.decode(value);

    Now you can infer this as an Iterable since you know that is an Iterable.

    I like to map like this:

    List.from(decodeMapOperation) 
           .map((jsonObject) {
              print(jsonObject['name']);
              return Mapper.fromJson(jsonObject); // You need to return something, you need a mapper for the object
           })
           .toList();
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search