Exception in json.decode : Closure: () => String from Function 'toString'

Question

I am getting some data from API in flutter. I am trying to decode the data using json.decode() but this decode function gives me the following error:

Closure: () => String from Function 'toString'

Here's my code:

Future<Product> createOrder() async {
    var client = new http.Client();
    var productModel = null;

    try {
      var response = await client
          .get(Uri.https('butterbasket.onrender.com', Strings.createOrderUrl));
      if (response.statusCode == 200) {
        var body = response.body;
        print("Body: $body");
        var jsonMap = json.decode(body);
        var productModel = Product.fromJson(jsonMap);
      }
    } catch (e) {
      print("Exception: ${e.toString}");
    }
    return productModel;
  }

Here is the Error Debug Console:

`body` is already a `String`, you don't need to use `.toString()` on it again — JideGuru, Feb 02 '22 at 19:31

score 2 · Accepted Answer · answered Feb 02 '22 at 20:34

2

You are running into issues because the data you are loading in is an array, but the model is an object. You'll need to do something like the following:

final List jsonProducts = json.decode(body)
final List<Product> products = 
     jsonProducts.map((jsonProduct) => Product.fromJson(jsonProduct)).toList();

and then if you only need the first item you can do:

final Product product = products[0]

But don't forget to check if the array is big enough.

answered Feb 02 '22 at 20:34

Developer Extraordinare

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BTW, The "error" you are getting is probably related to how you are trying to print the error. try just calling `print(e)` instead. – Developer Extraordinare Feb 02 '22 at 20:42

score 0 · Answer 2 · answered Feb 02 '22 at 20:27

Your Future function must return an optional Product?, otherwise your future will never find a result as you are declaring it inside the function.

Instead of:

Future<Product> createOrder() async {}

Use:

Future<Product?> createOrder() async {}

Finally your async snapshot and FutureBuilder type should be of type <Product?>.

Exception in json.decode : Closure: () => String from Function 'toString'

2 Answers2