send data to api code example

Example 1: post json in flutter

import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

Future<Album> createAlbum(String title) async {
  final http.Response response = await http.post(
    'https://jsonplaceholder.typicode.com/albums',
    headers: <String, String>{
      'Content-Type': 'application/json; charset=UTF-8',
    },
    body: jsonEncode(<String, String>{
      'title': title,
    }),
  );

  if (response.statusCode == 201) {
    return Album.fromJson(jsonDecode(response.body));
  } else {
    throw Exception('Failed to create album.');
  }
}

class Album {
  final int id;
  final String title;

  Album({this.id, this.title});

  factory Album.fromJson(Map<String, dynamic> json) {
    return Album(
      id: json['id'],
      title: json['title'],
    );
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  MyApp({Key key}) : super(key: key);

  @override
  _MyAppState createState() {
    return _MyAppState();
  }
}

class _MyAppState extends State<MyApp> {
  final TextEditingController _controller = TextEditingController();
  Future<Album> _futureAlbum;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Create Data Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Create Data Example'),
        ),
        body: Container(
          alignment: Alignment.center,
          padding: const EdgeInsets.all(8.0),
          child: (_futureAlbum == null)
              ? Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: <Widget>[
                    TextField(
                      controller: _controller,
                      decoration: InputDecoration(hintText: 'Enter Title'),
                    ),
                    ElevatedButton(
                      child: Text('Create Data'),
                      onPressed: () {
                        setState(() {
                          _futureAlbum = createAlbum(_controller.text);
                        });
                      },
                    ),
                  ],
                )
              : FutureBuilder<Album>(
                  future: _futureAlbum,
                  builder: (context, snapshot) {
                    if (snapshot.hasData) {
                      return Text(snapshot.data.title);
                    } else if (snapshot.hasError) {
                      return Text("${snapshot.error}");
                    }

                    return CircularProgressIndicator();
                  },
                ),
        ),
      ),
    );
  }
}

Example 2: send json body http get flutter

final queryParameters = {
  'name': 'Bob',
  'age': '87',
};
final uri = Uri.http('www.example.com', '/path', queryParameters);
final headers = {HttpHeaders.contentTypeHeader: 'application/json'};
final response = await http.get(uri, headers: headers);

Example 3: what to sent on request on api

REQUEST :(request url,http methods,header,query param, param,body,cookie)

1-)Request Url where we have Endpoint (domain:Port/Endpoints)

2-)HTTP METHODS(Get, Post, Put, Patch, Delete, Header)

Get: For to retrieve resources from the server
Post: to send or add resource to the server
Put: For update the resources in the server
Patch: For partial update the resource
Delete: For deleting the resource in the server
Head: To get header from the response not the body

3-)HEADER is metadata is about the request,
basically providing more information along
with the request.

-Content Type header : to specify what kind of
 data we are sending to the server
-Accept Header : to specify what kind of data 
 format you want to get in the response like (json or xml)
-Authorization header : used to provide the
 Bearer token in many api's.

4-)Query Parameter: A key value pair usually
 for filtering result

5-)Parameter: for identifying single resource
 among the list of resources.
6-)Payload(BODY): for POST,PUT,PATCH request
(json,xml,plainText,URL encoded for data)
7-)Cookie

RESPONSE :(STATUS CODE,PAYLOAD(body),HEADER,COOKIE,
           TIME(spent to get response))

1-Status Code:
   2xx - Success
   4xx - Client Error
   5xx - Server Error

2-Payload(Body) : 
The actual resource we got from the server.
Content type can be : plain text, json, xml, html, json etc.

3- Metadata about response to provide more information

4- Cookie

5- Time for getting spended time for the response