Flutter - how to correctly parse Json data when response is nested?

Question

new to Flutter, I managed to parse this response from a RESt api:

Provider:

  factory Contacts.fromList(final List<Map<String, dynamic>> list) {
    final Contacts contacts = Contacts();
    for (final Map<String, dynamic> map in list) {
      contacts.add(Contact.fromMap(map));
    }
    return contacts;
  }

then in my service:

 if (response.statusCode == 200) {
      return Contacts.fromList(
          jsonDecode(response.body).cast<Map<String, dynamic>>());

when the data comes in this format:

[
    {
        "id": 1,
        "first_name": "Dave",
        "last_name": "Laweles",
        "email": "[email protected]",

This all works perfectly, but now, my dummy API is returning the data in this format:

{
    "data": [
       {
        "id": 1,
        "first_name": "Dave",
        "last_name": "Laweles",
        "email": "[email protected]",
        }, .....
     ],
    "total": 100,
    "page": 0,
    "limit": 10,
    "offset": 0
}

And now I cannot figure out how to change my Provider factory constructor to Parse correctly this result object. Besides the fact that now the response is wrapped in another object, I also need to retrieve the Pagination data (total, page, limit) as well in my Parsing.

Abbas Jafari · Accepted Answer · 2021-03-01 07:45:50Z

1

You can do it like below:

actory Contacts.fromList(final List<Map<String, dynamic>> list) {
    final Contacts contacts = Contacts();
    for (final Map<String, dynamic> map in list['data']) {
      contacts.add(Contact.fromMap(map));
    }
    return contacts;
  }

And I hope it works for you.

answered Mar 1, 2021 at 7:45

Abbas Jafari

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1 Comment

AJ- Over a year ago

this was the first thing I tried and does not work The type 'Map<String, dynamic>' used in the 'for' loop must implement Iterable.dartfor_in_of_invalid_type The argument type 'String' can't be assigned to the parameter type 'int' I will also need to extrapolate the other data on the same level as "data"

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