How to retrieve and arrange various JSON arrays into lists using Flutter?

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To retrieve and arrange various JSON arrays into lists using Flutter, you can follow the below steps:

1. First, you need to load the JSON data using the json.decode() method.

2. Next, you can create the list objects for each array in the JSON data.

3. Once you have created the list objects, you can loop through each item in the JSON array and add it to the corresponding list.

4. Finally, you can return the lists as your data model for your Flutter UI.

Here is an example code snippet that retrieves JSON data with two arrays contacts and tasks and arranges them into lists:

import 'dart:convert';

class Contact {
  final String name;
  final String email;

  Contact({
    required this.name,
    required this.email,
  });
}

class Task {
  final String title;
  final bool completed;

  Task({
    required this.title,
    required this.completed,
  });
}

class DataModel {
  final List<Contact> contacts;
  final List<Task> tasks;

  DataModel({
    required this.contacts,
    required this.tasks,
  });
}

DataModel parseJson(String jsonString) {
  final jsonData = json.decode(jsonString);

  final List<Contact> contacts = List<Contact>.from(jsonData['contacts'].map((x) => Contact(
    name: x['name'],
    email: x['email'],
  )));

  final List<Task> tasks = List<Task>.from(jsonData['tasks'].map((x) => Task(
    title: x['title'],
    completed: x['completed'],
  )));

  return DataModel(
    contacts: contacts,
    tasks: tasks,
  );
}

In this example, we have defined two model classes Contact and Task that represent the data structure of each array in the JSON data. We have also defined a DataModel class that contains the two lists of contacts and tasks.

The parseJson method takes a JSON string as input and returns a DataModel object that contains the list of contacts and tasks. We use the json.decode method to convert the JSON string to a map object. We then create the contacts and tasks lists by mapping each item in the corresponding JSON array to an instance of the Contact and Task classes.

You can use this DataModel object as the data source for your Flutter UI.