Parsing complex JSON in Flutter
Gives a detailed explanation of working with simple and complex JSON structures using dart:convert library in Flutter along with a sample project with 6+ examples to experiment with.
Tutorial
Read the Medium article here
Types of JSON structures
- Simple map
- Simple structure with arrays
- Simple nested structures
- Nested structure with Lists
- List of maps
- Complex nested structures
- Simple structure with Nested Maps [parsed using json_serializable library]
- Demo for Network Calls with examples for GET, POST methods along with FutureBuilder and .then()
How to work with Network Calls?
Not covered in the article
Let's take this API as an example.
Take a look at post_model.dart for the model class and utility methods. I produced it using this converter tool
GET getAllPosts
//services.dart
Future<List<Post>> getAllPosts() async {
final response = await http.get(url);
return allPostsFromJson(response.body);
}// As a part of your UI widget, e.g body of Scaffold widget
FutureBuilder<List<Post>>(
future: getAllPosts(),
builder: (context, snapshot) {
if(snapshot.hasData)
return Text('Title from Post JSON : ${snapshot.data[0].title}');
else
return CircularProgressIndicator();
}
)GET getPost (to get a particular POST by id)
//services.dart
Future<Post> getPost() async{
final response = await http.get('$url/1'); // the number is the id of the item being accessed
return postFromJson(response.body);
}// As a part of your UI widget, e.g body of Scaffold widget
FutureBuilder<Post>(
future: getPost(),
builder: (context, snapshot) {
if(snapshot.hasData)
return Text('Title from Post JSON : ${snapshot.data.title}');
else
return CircularProgressIndicator();
}
)POST createPost
//services.dart
Future<http.Response> createPost(Post post) async{
final response = await http.post('$url',
headers: {
HttpHeaders.contentTypeHeader: 'application/json'
},
body: postToJson(post)
);
return response;
} //call this function when you want to create a new post
callAPI(){
Post post = Post(
body: 'Testing body body body',
title: 'Flutter jam6'
); // creating a new Post object to send it to API
createPost(post).then((response){
if(response.statusCode > 200)
print(response.body);
else
print(response.statusCode);
}).catchError((error){
print('error : $error');
});
}