Extract data from complex JSON in Flutter - json

Question

I'm working in extract data from more complex JSON with unknown structure, its structure changes with operation ,
JSON sample link :http://afs-i.com/json.json
Kindly find my code here : http://afs-i.com/main.dart
Thanks in advance
Update:
I extracted the data using PHP code, you can find result here: http://afs-i.com/json.php
Kindly this is my PHP code:
$arraycars=array();
$y=json_decode($x);
// echo "<pre>";
// var_dump($y->tree[0]->children);
foreach ($y->tree[0]->children as $f) {
if(isset($f->vid)){
global $arraycars;
$arraycars[]=$f;
} elseif(isset($f->children)){
if(sizeof($f->children) > 0){
coolectcars($f->children);
}
}
}
function coolectcars($array){
// var_dump($array);
foreach ($array as $f) {
if(isset($f->vid)){
global $arraycars;
$arraycars[]=$f;
} elseif(isset($f->children)){
if(sizeof($f->children) > 0){
coolectcars($f->children);
}
}
}
}
echo json_encode($arraycars);
Update:2
I have problem now with null error for this code:
The error:
I/flutter ( 4264): NoSuchMethodError: The method 'forEach' was called on
null.
I/flutter ( 4264): Receiver: null
I/flutter ( 4264): Tried calling: forEach(Closure: (Children) => Null)
The code:
List<Children> cars = [];
Queue numQ = new Queue();
numQ.addAll(parsed["tree"][0]["children"]);
Iterator i = numQ.iterator;
while (i.moveNext()) {
// print("ddddddd ${i.current}");
if (i.current.containsKey("vid")) {
cars.add(new Children(
i.current['vid'], i.current['protocol'], i.current['datetime'],
i.current['gpss']));
} else {
Queue numQ = new Queue();
if (i.current["children"] != null) {
numQ.addAll(i.current["children"]);
// iterate(numQ);
List<Children> carse=[];
carse = iterate(numQ);
carse.forEach((data){
cars.add(data);
}) ;
}
}
}
cars.forEach((data) {
print(data.toString());
});
List<Children> iterate(Queue numQ) {
List<Children> cars=new List<Children>();
Iterator i = numQ.iterator;
while (i.moveNext()) {
print("ddddddd ${i.current}");
if (i.current.containsKey("vid")) {
cars.add(new Children(
i.current['vid'], i.current['protocol'], i.current['datetime'],
i.current['gpss']));
} else {
if (i.current["children"] != null) {
Queue numQ = new Queue();
numQ.addAll(i.current["children"]);
List<Children> carse=[];
carse = iterate(numQ);
carse.forEach((data){
cars.add(data);
}) ;
}
}
return cars;
}
}

Answer 1

I prefer using built_value to do json deserialization/ serialization. It's more elegant. You don't need to write down fromJson by yourself. built_value will generate deserializers / serializer for you. You can check built_value's github or this and this articles.

Answer 2

A good place for convert JSON to dart here
hats to reddit url
just copy your json into the textbox and generate, it will auto generate for you.
With this, you can call fromJson and feed it the json, then you can also get auto complete for it
eg: usage
final response =
await http.get('http://afs-i.com/json.json');
if (response.statusCode == 200) {
final Autogenerated respJson = Autogenerated.fromJson(json.decode(response.body));
print(respJson.tree[0].userId);
}

Answer 3

insert this import 'dart:convert';
into your widget file at top.
lets say you have your json in
var response
then
var jsonDecoded= json.decode(response);
now you can get name and user_id like this:
var user_id= jsonDecoded["tree"][0]["user_id"];
var name = jsonDecoded["tree"][0]["name"];
NOTE : I get these values from the first object (0 index). If you want values for each object , you can loop to get it.

Answer 4

The final answer i reach:
final parsed = json.decode(response.body);
List<Children> cars = [];
Queue numQ = new Queue();
numQ.addAll(parsed["tree"][0]["children"]);
Iterator i = numQ.iterator;
while (i.moveNext()) {
if (i.current.containsKey("vid")) {
cars.add(new Children(
i.current['vid'],
i.current['datetime'],
));
} else {
Queue numQ = new Queue();
if (i.current["children"].toString() != "[]") {
numQ.addAll(i.current["children"]);
List<Children> carse = [];
carse = iterate(numQ);
carse.forEach((data) {
cars.add(data);
});
}
}
}
List<Children> iterate(Queue numQ) {
List<Children> cars = new List<Children>();
Iterator i = numQ.iterator;
while (i.moveNext()) {
if (i.current.containsKey("vid")) {
if (i.current.containsKey("vid")) {
cars.add(new Children(
i.current['vid'],
i.current['datetime'],
));
}
} else {
if (i.current["children"].toString() != "[]") {
Queue numQ = new Queue();
if (i.current["children"].toString() != "[]") {
numQ.addAll(i.current["children"]);
List<Children> carse = [];
carse = iterate(numQ);
carse.forEach((data) {
cars.add(data);
});
}
}
}
return cars;
}