I am trying to create model and parse json data from api
for that i created the model class you can see below
class FeatureModel {
String? PlanFeatures;
bool? FeatureStatus;
FeatureModel({this.PlanFeatures, this.FeatureStatus});
FeatureModel.fromJson(parsonJson) {
PlanFeatures = parsonJson['PlanFeatures'];
FeatureStatus = parsonJson['FeatureStatus'];
}
}
now i am trying to parse json with the help of loop
let me show you my method
List<FeatureModel> featureModel = [];
Uri featureAPI = Uri.parse(
planFeatureApi);
apiCall() async {
try {
http.Response response = await http.get(featureAPI);
// print(response.statusCode);
if (response.statusCode == 200) {
var decode = json.decode(response.body);
print(decode);
for (var i = 0; i < decode.length; i++) {
print(i);
featureModel.add(
FeatureModel.fromJson(decode[i]),
);
}
}
} catch (e) {}
}
I am calling it here
onPressed: () async{
await apiCall();
}
but the problem is here
loop is not working while parsing data
in that particular code i remains on 0 only
when i removes featureModel.add( FeatureModel.fromJson(decode[i]), ); i started increaing till 10
please let me know if i am making any mistake or what
thanks in advance
Here is the sample of api respone
[{"PlanFeatures":"Video Link Sharing","FeatureStatus":"true"},{"PlanFeatures":"Email \u0026amp; Telephonic Support","FeatureStatus":"true"},{"PlanFeatures":"Remove Pixeshare Branding","FeatureStatus":"false"},{"PlanFeatures":"Add Custom logo on uploaded photos","FeatureStatus":"false"},{"PlanFeatures":"Get Visitor Info","FeatureStatus":"false"},{"PlanFeatures":"Mobile Apps","FeatureStatus":"false"},{"PlanFeatures":"Send Questionnaries","FeatureStatus":"false"},{"PlanFeatures":"Create \u0026amp; Send Quotation","FeatureStatus":"false"},{"PlanFeatures":"Online Digital Album Sharing","FeatureStatus":"false"},{"PlanFeatures":"Analytics","FeatureStatus":"false"}]
thanks
I found many errors, first, the fromJson is not a factory constructor and doesn't return a class instance from the JSON.
the second one is that the bool values from the sample you added are String not a bool so we need to check over it.
try changing your model class to this:
class FeatureModel {
String? PlanFeatures;
bool? FeatureStatus;
FeatureModel({this.PlanFeatures, this.FeatureStatus});
factory FeatureModel.fromJson(parsonJson) {
return FeatureModel(
PlanFeatures: parsonJson['PlanFeatures'],
FeatureStatus: parsonJson['FeatureStatus'] == "false" ? false : true,
);
}
}
Related
this code is for fetching data from json api , there is just one error in the code , and this is the error :
error
class RemoteService {
Future<List<Adhan>?> getAdhan() async {
var client = http.Client();
var uri = Uri.parse("https://api.pray.zone/v2/times/today.json?city=paris");
var response = await client.get(uri);
if (response.statusCode == 200) {
var json = response.body;
return adhanFromJson(json);
}
}
}
I tried to search in the Internet and YouTube for any problem similar to my problem, I did not find anything to help me.
how can i fix this error ?
Your function named adhanFromJson probably returns a Adhan, while getAdhan expects you to return a List<Adhan> or null.
Either change the return type of getAdhan or return a List<Adhan>.
I have the following method which is use dto verify a ticket/token
var ticketArray = ticket.split('|');
//First check to verify token using simple versification algo
if (widget.eventID.toString() != (ticketArray[0])) {
setState(() {
ticketMainMsg = 'This QR code is NOT VALID';
ticketsubtitle = ticketArray.length != 2
? 'The QR code is fake'
: 'QR code could belong to another event';
ticketStatus = false;
return;
});
}
//Make API call
ticketModel = HttpVerifyTicketPost(
eventId: widget.eventID,
ticket: ticket,
scannerId: widget.scannerId,
).verifyTicket();
}
From above, you can see I do a very simple check on the qr code/token if this simple step fails, I don't bother making an API call and I set the state based on these values.
However if the check passes, then I proceed to make an API call to the server to fully verify the token/code.
My issue is I am struggling to now assign the values from the API call to the ticketStatus, ticketMainMsgand ticketsubtitle parameters. Can anyone helo shed some light. I am quite new to flutter but I am aware that the TicketModel will be a type of Future. My background is PHP so forgive me!
EDIT: The httpVerifyTicket Class
class HttpVerifyTicketPost {
String ticket;
int someId;
int anotherId;
HttpVerifyTicketPost(
{required this.ticket, required this.someId, required this.anotherId});
String verifyURL =
'https://api.com/api/vendors/scanner/native/verify/ticket';
Future<TicketModel> verifyTicket() async {
var storage = await SharedPreferences.getInstance();
var code= storage.getString('code');
var client = http.Client();
var ticketModel = null;
var body = {
'ticket': ticket,
'scanner': scannerCode,
'someId': someId,
'anotherId': anotherId
};
try {
var url = Uri.parse(verifyURL);
var res = await client.post(url, body: jsonEncode(body));
if (res.statusCode == 200) {
var jsonString = res.body;
var jsonMap = json.decode(jsonString);
ticketModel = TicketModel.fromJson(jsonMap);
}
return ticketModel;
} catch (Exception) {
return ticketModel;
}
}
}
Try this please
HttpVerifyTicketPost(
eventId: widget.eventID,
ticket: ticket,
scannerId: widget.scannerId,
).verifyTicket().then((value){setState(() {
ticketModel=value
});
});
I don't quite understand what you want to achieve, but maybe you need to add an asynchronous method like
ticketModel = await HttpVerifyTicketPost( //add await eventId: widget.eventID, ticket: ticket, scannerId: widget.scannerId, ).verifyTicket();
and you must add async like Future Foo() async {your code...}
I'm trying to prepend the string )]}',\n to any response body that's JSON. I thought that an IAsyncResultFilter would be what I needed to use, but I'm not having luck. If I use the below code, it appends the text to the response since calling await next() writes to the response pipe. If I try and look at the context before that though, I can't tell what the response will actually be to know if it's JSON.
public class JsonPrefixFilter : IAsyncResultFilter
{
public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
{
var executed = await next();
var response = executed.HttpContext.Response;
if (response.ContentType == null || !response.ContentType.StartsWith("application/json"))
return;
var prefix = Encoding.UTF8.GetBytes(")]}',\\n");
var bytes = new ReadOnlyMemory<byte>(prefix);
await response.BodyWriter.WriteAsync(bytes);
}
}
Thanks to timur's post I was able to come up with this working solution.
public class JsonPrefixFilter : IAsyncResultFilter
{
public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
{
var response = context.HttpContext.Response;
// ASP.NET Core will always send the contents of the original Body stream back to the client.
var originalBody = response.Body;
// We want to write into a memory stream instead of the actual response body for now.
var ms = new MemoryStream();
response.Body = ms;
// After this call the body is written into the memory stream and the properties
// of the response object are populated.
await next();
if (response.ContentType != null && response.ContentType.StartsWith("application/json")) {
var prefix = Encoding.UTF8.GetBytes(")]}',\\n");
var prefixMemoryStream = new MemoryStream();
await prefixMemoryStream.WriteAsync(prefix);
await prefixMemoryStream.WriteAsync(ms.ToArray());
prefixMemoryStream.Seek(0, SeekOrigin.Begin);
// Now put the stream back that .NET wants to use and copy the memory stream to it.
response.Body = originalBody;
await prefixMemoryStream.CopyToAsync(response.Body);
} else {
// If it's not JSON, don't muck with the stream, so just put things back.
response.Body = originalBody;
ms.Seek(0, SeekOrigin.Begin);
await ms.CopyToAsync(response.Body);
}
}
}
Update:
I never liked the above, so I switched to this solution. Instead of calling AddJsonOptions, I took inspiration from ASP.NET's formatter to use this instead:
public class XssJsonOutputFormatter : TextOutputFormatter
{
private static readonly byte[] XssPrefix = Encoding.UTF8.GetBytes(")]}',\n");
public JsonSerializerOptions SerializerOptions { get; }
public XssJsonOutputFormatter()
{
SerializerOptions = new() {
PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
ReferenceHandler = ReferenceHandler.IgnoreCycles
};
SupportedEncodings.Add(Encoding.UTF8);
SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse("application/json"));
}
public override sealed async Task WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
{
ArgumentNullException.ThrowIfNull(context, nameof(context));
ArgumentNullException.ThrowIfNull(selectedEncoding, nameof(selectedEncoding));
var httpContext = context.HttpContext;
var objectType = context.Object?.GetType() ?? context.ObjectType ?? typeof(object);
var responseStream = httpContext.Response.Body;
try {
await responseStream.WriteAsync(XssPrefix);
await JsonSerializer.SerializeAsync(responseStream, context.Object, objectType, SerializerOptions, httpContext.RequestAborted);
await responseStream.FlushAsync(httpContext.RequestAborted);
} catch (OperationCanceledException) when (context.HttpContext.RequestAborted.IsCancellationRequested) {
}
}
}
Now, when you call .AddControllers() you just set that as the first output formatter:
services.AddControllers(options => {
options.Filters.Add(new ProducesAttribute("application/json"));
options.OutputFormatters.Insert(0, new XssJsonOutputFormatter());
});
Obviously you could improve this to take serialization options in the constructor, but all my project would work exactly like the above so I just hardcoded it right in.
You could've used Seek on a steam to rewind it. Issue is, you can only keep adding onto default HttpResponseStream, it does not support seeking.
So you can employ the technique from this SO answer and temporarily replace it with MemoryStream:
private Stream ReplaceBody(HttpResponse response)
{
var originBody = response.Body;
response.Body = new MemoryStream();
return originBody;
}
private async Task ReturnBodyAsync(HttpResponse response, Stream originalBody)
{
response.Body.Seek(0, SeekOrigin.Begin);
await response.Body.CopyToAsync(originalBody);
response.Body = originalBody;
}
public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
{
var originalBody = ReplaceBody(context.HttpContext.Response); // replace the default stream with MemoryStream
await next(); // we probably dont care about the return of this call. it's all in the context
var response = context.HttpContext.Response;
if (response.ContentType == null || !response.ContentType.StartsWith("application/json"))
return;
var prefix = Encoding.UTF8.GetBytes(")]}',\\n");
var bytes = new ReadOnlyMemory<byte>(prefix);
response.Body.Seek(0, SeekOrigin.Begin); // now you can seek. but you will notice that it overwrites the response so you might need to make extra space in the buffer
await response.BodyWriter.WriteAsync(bytes);
await ReturnBodyAsync(context.HttpContext.Response, originalBody); // revert the reference, copy data into default stream and return it
}
this is further complicated by the fact that you need to restore reference to original stream, so you have to careful around that.
This SO answer has a bit more context.
i'm using a builder for a search page in my application, basically i get data from a json file,
my issue is that if i try to search for a new word, the old result will still be shown and the new one are going to be shown under them.
here is how i get data from my website:
Future<List<Note>> fetchNotes() async {
var url = 'https://sample.com/';
var response = await http.get(url + _controller.text.trim());
var notes = List<Note>();
if (response.statusCode == 200) {
var notesJson = json.decode(response.body);
for (var noteJson in notesJson) {
notes.add(Note.fromJson(noteJson));
}
} else {
ercode = 1;
}
return notes;
}
fetchNotes().then((value) {
setState(() {
_notes.addAll(value);
});
});
if (_notes[0] == null) {
ercode = 2;
}
}
and i display data like this:
here is full example for showing that data
I think you should use "clear()".
fetchNotes().then((value) {
setState(() {
_notes.clear();
_notes.addAll(value);
});
});
I tried to fetch data from the internet with moviedb API, I followed the tutorial at https://flutter.io/cookbook/networking/fetch-data/
but I'm getting the below error.
Invalid argument(s): Illegal argument in isolate message : (object is a closure - Function 'createDataList':.)
This my code
Future<List<DataModel>> fetchData() async{
final response = await http.get("https://api.themoviedb.org/3/movie/now_playing?api_key=d81172160acd9daaf6e477f2b306e423&language=en-US");
if(response.statusCode == 200){
return compute(createDataList,response.body.toString());
}
}
List<DataModel> createDataList(String responFroJson) {
final parse = json.decode(responFroJson).cast<Map<String, dynamic>>();
return parse.map<DataModel> ((json) => DataModel.fromtJson(json)).toList();
}
Screenshot of the error message
compute can only take a top-level function, but not instance or static methods.
Top-level functions are functions declared not inside a class
and not inside another function
List<DataModel> createDataList(String responFroJson) {
...
}
class SomeClass { ... }
should fix it.
https://docs.flutter.io/flutter/foundation/compute.html
R is the type of the value returned. The callback argument must be a top-level function, not a closure or an instance or static method of a class.
As per today (2020. Aug) the compute is working fine with static methods.
For me, the issue was that I was trying to return a http.Response object from the compute() methods.
What I did is I've created a simplified version of this class, containing what I need:
class SimpleHttpResponse {
String body;
int statusCode;
Map<String, String> headers;
}
Then I've updated the original method from this:
static Future<http.Response> _executePostRequest(EsBridge bridge) async {
return await http.post(Settings.bridgeUrl, body: bridge.toEncryptedMessage());
}
to this:
static Future<SimpleHttpResponse> _executePostRequest(EsBridge bridge) async {
http.Response result = await http.post(Settings.bridgeUrl, body: bridge.toEncryptedMessage());
if (result == null) {
return null;
}
SimpleHttpResponse shr = new SimpleHttpResponse();
shr.body = result.body;
shr.headers = result.headers;
shr.statusCode = result.statusCode;
return shr;
}
Worked like charm after this change. Hope this helps somebody ranning into similar problem.