Getting the Json data in flutter from file

Question

I want to get data from json file but it returning error.I have been trying to fetch json data from my flutter app.Kindly tell me what i am doing wrong.The Error file is also included at the end.I want the json data in this format because i want to get data from wordpres rest api of page through id. Here is my code. main.dart

import 'dart:convert';

import 'package:flutter/material.dart';

main() => runApp(HomePage());

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: FutureBuilder(
          future: DefaultAssetBundle.of(context).load("assets/file.json"),
          builder: (context, snapshot) {
            var mydata = json.decode(snapshot.data.toString());

            return Center(child: Text(mydata["name"]));
          },
        ),
      ),
    );
  }
}

file.json

{
    "name": "Shahryar"
}

Error

Restarted application in 2,001ms.
I/flutter (24449): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (24449): The following NoSuchMethodError was thrown building FutureBuilder<ByteData>(dirty, state:
I/flutter (24449): _FutureBuilderState<ByteData>#87cd8):
I/flutter (24449): The method '[]' was called on null.
I/flutter (24449): Receiver: null
I/flutter (24449): Tried calling: []("name")
I/flutter (24449):
I/flutter (24449): The relevant error-causing widget was:
[38;5;248mI/flutter (24449):   FutureBuilder<ByteData>[39;49m
I/flutter (24449):
I/flutter (24449): When the exception was thrown, this was the stack:
[38;5;244mI/flutter (24449): #0      Object.noSuchMethod  (dart:core-patch/object_patch.dart:53:5)[39;49m
[38;5;248mI/flutter (24449): #1      _HomePageState.build.<anonymous closure>[39;49m
[38;5;244mI/flutter (24449): #2      _FutureBuilderState.build[39;49m
[38;5;244mI/flutter (24449): #3      StatefulElement.build[39;49m
[38;5;244mI/flutter (24449): #4      ComponentElement.performRebuild[39;49m
[38;5;244mI/flutter (24449): #5      StatefulElement.performRebuild[39;49m
[38;5;244mI/flutter (24449): #6      Element.rebuild[39;49m
[38;5;244mI/flutter (24449): #7      ComponentElement._firstBuild[39;49m
[38;5;244mI/flutter (24449): #8      StatefulElement._firstBuild[39;49m
[38;5;244mI/flutter (24449): #9      ComponentElement.mount[39;49m
I/flutter (24449): ...     Normal element mounting (19 frames)
[38;5;244mI/flutter (24449): #28     Element.inflateWidget[39;49m
[38;5;244mI/flutter (24449): #29     MultiChildRenderObjectElement.mount[39;49m
I/flutter (24449): ...     Normal element mounting (191 frames)
[38;5;244mI/flutter (24449): #220    Element.inflateWidget[39;49m
[38;5;244mI/flutter (24449): #221    MultiChildRenderObjectElement.mount[39;49m
I/flutter (24449): ...     Normal element mounting (255 frames)
[38;5;244mI/flutter (24449): #476    Element.inflateWidget[39;49m
[38;5;244mI/flutter (24449): #477    Element.updateChild[39;49m
[38;5;244mI/flutter (24449): #478    RenderObjectToWidgetElement._rebuild[39;49m
[38;5;244mI/flutter (24449): #479    RenderObjectToWidgetElement.mount[39;49m
[38;5;244mI/flutter (24449): #480    RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure>[39;49m
[38;5;244mI/flutter (24449): #481    BuildOwner.buildScope[39;49m
[38;5;244mI/flutter (24449): #482    RenderObjectToWidgetAdapter.attachToRenderTree[39;49m
[38;5;244mI/flutter (24449): #483    WidgetsBinding.attachRootWidget[39;49m
[38;5;244mI/flutter (24449): #484    WidgetsBinding.scheduleAttachRootWidget.<anonymous closure>[39;49m
I/flutter (24449): (elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, and dart:async-patch)
I/flutter (24449):
I/flutter (24449): ════════════════════════════════════════════════════════════════════════════════════════════════════

[38;5;248m════════ Exception caught by widgets library ═══════════════════════════════════[39;49m
[38;5;244mThe following FormatException was thrown building FutureBuilder<ByteData>(dirty, state: _FutureBuilderState<ByteData>#87cd8):[39;49m
Unexpected character (at character 1)
TypedDataView(cid: 146)
^

[38;5;244mThe relevant error-causing widget was[39;49m
    [38;5;248mFutureBuilder<ByteData>[39;49m
[38;5;244mWhen the exception was thrown, this was the stack[39;49m
[38;5;244m#0      _ChunkedJsonParser.fail  (dart:convert-patch/convert_patch.dart:1394:5)[39;49m
[38;5;244m#1      _ChunkedJsonParser.parseNumber  (dart:convert-patch/convert_patch.dart:1261:9)[39;49m
[38;5;244m#2      _ChunkedJsonParser.parse  (dart:convert-patch/convert_patch.dart:926:22)[39;49m
[38;5;244m#3      _parseJson  (dart:convert-patch/convert_patch.dart:31:10)[39;49m
[38;5;244m#4      JsonDecoder.convert  (dart:convert/json.dart:495:36)[39;49m
[38;5;244m...[39;49m
[38;5;248m════════════════════════════════════════════════════════════════════════════════[39;49m
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=-1)
D/OpenSSLLib(24449): OpensslErr:Module:30(110:); file:external/boringssl/src/crypto/fipsmodule/cipher/cipher.c ;Line:563;Function:EVP_CIPHER_CTX_set_key_length
D/Surface (24449): Surface::connect(this=0x792c29f000,api=1)
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=-1)
D/Surface (24449): Surface::disconnect(this=0x792c29e000,api=1)
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
D/OpenSSLLib(24449): OpensslErr:Module:30(110:); file:external/boringssl/src/crypto/fipsmodule/cipher/cipher.c ;Line:563;Function:EVP_CIPHER_CTX_set_key_length
D/Surface (24449): Surface::connect(this=0x792c29e000,api=1)
D/OpenSSLLib(24449): OpensslErr:Module:30(110:); file:external/boringssl/src/crypto/fipsmodule/cipher/cipher.c ;Line:563;Function:EVP_CIPHER_CTX_set_key_length
D/Surface (24449): Surface::connect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=-1)
D/Surface (24449): Surface::disconnect(this=0x792c29e000,api=1)
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 0, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
D/OpenSSLLib(24449): OpensslErr:Module:30(110:); file:external/boringssl/src/crypto/fipsmodule/cipher/cipher.c ;Line:563;Function:EVP_CIPHER_CTX_set_key_length
D/Surface (24449): Surface::connect(this=0x792c29e000,api=1)
D/OpenSSLLib(24449): OpensslErr:Module:30(110:); file:external/boringssl/src/crypto/fipsmodule/cipher/cipher.c ;Line:563;Function:EVP_CIPHER_CTX_set_key_length
D/Surface (24449): Surface::connect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=1)
D/Surface (24449): Surface::disconnect(this=0x792c29f000,api=-1)
D/Surface (24449): Surface::disconnect(this=0x792c29e000,api=1)
V/PhoneWindow(24449): DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@6820332, this = DecorView@d00c883[MainActivity]
Application finished.
Exited (sigterm)

change the load() function to loadString() .. should work. Let me know if it worked. — Ratnadeep
– Ratnadeep, Commented Apr 9, 2020 at 13:54

encubos · Accepted Answer · 2020-04-09 23:44:06Z

2

You are reading a text file.

In this line

DefaultAssetBundle.of(context).load("assets/file.json"),

Change load for loadString

DefaultAssetBundle.of(context).loadString("assets/file.json"),

For reference:

load (String key) → Future< ByteData >

Retrieve a binary resource from the asset bundle as a data stream

-

loadString (String key, {bool cache: true}) → Future< String >

Retrieve a string from the asset bundle

https://api.flutter.dev/flutter/services/AssetBundle-class.html

edited Apr 9, 2020 at 23:44

answered Apr 9, 2020 at 23:37

encubos

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Michael T Over a year ago

Is there a way of loading data from device e.g. File("/sdcard/Download/data.json")? Instead of from the flutter asset files?

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