如何在颤振中从 JSON 文件中获取所有命令 id?

Question

我是 Flutter的初学者，我正在尝试使用 Flutter 从 JSON 文件中获取值。 我可以获取设备 ID 和设备名称的一些值，但我真的不知道如何在命令中获取 id。 提前感谢您的帮助。

这是我的 JSON 文件：

[
{
"id": "15622bf9-969c-4f54-bd80-265a8132c97a",
"name": "Random-Integer-Generator01",
"adminState": "UNLOCKED",
"operatingState": "ENABLED",
"lastConnected": 0,
"lastReported": 0,
"labels": [
"device-random-example"
],
"location": null,
"commands": [
{
"created": 1572962679310,
"modified": 1572962679310,
"id": "f07b4a42-4358-4394-bc71-76f292f8359f",
"name": "GenerateRandomValue_Int8",
"get": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int8",
"responses": [
{
"code": "503",
"description": "service unavailable"
}
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/f07b4a42-4358-4394-bc71-76f292f8359f"
},
"put": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int8",
"parameterNames": [
"Min_Int8",
"Max_Int8"
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/f07b4a42-4358-4394-bc71-76f292f8359f"
}
},
{
"created": 1572962679336,
"modified": 1572962679336,
"id": "86eafeb6-f359-40e7-b6c1-d35e9e9eb625",
"name": "GenerateRandomValue_Int16",
"get": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int16",
"responses": [
{
"code": "503",
"description": "service unavailable"
}
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/86eafeb6-f359-40e7-b6c1-d35e9e9eb625"
},
"put": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int16",
"parameterNames": [
"Min_Int16",
"Max_Int16"
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/86eafeb6-f359-40e7-b6c1-d35e9e9eb625"
}
},
{
"created": 1572962679337,
"modified": 1572962679337,
"id": "bb492384-8c72-4ab6-9a84-24a3be0b934e",
"name": "GenerateRandomValue_Int32",
"get": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int32",
"responses": [
{
"code": "503",
"description": "service unavailable"
}
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/bb492384-8c72-4ab6-9a84-24a3be0b934e"
},
"put": {
"path": "/api/v1/device/{deviceId}/GenerateRandomValue_Int32",
"parameterNames": [
"Min_Int32",
"Max_Int32"
],
"url": "http://edgex-core-command:48082/api/v1/device/15622bf9-969c-4f54-bd80-265a8132c97a/command/bb492384-8c72-4ab6-9a84-24a3be0b934e"
}
}
]
},
{
"id": "97dcd3b2-f4f1-4a1a-9520-2ff62c697945",
"name": "Random-Boolean-Device",
"adminState": "UNLOCKED",
"operatingState": "ENABLED",
"lastConnected": 0,
"lastReported": 0,
"labels": [
"device-virtual-example"
],
"location": null,
"commands": [
{
"created": 1572962679576,
"modified": 1572962679576,
"id": "1bc520ef-a9a4-43c7-8098-dcc5faea9ea1",
"name": "RandomValue_Bool",
"get": {
"path": "/api/v1/device/{deviceId}/RandomValue_Bool",
"responses": [
{
"code": "503",
"description": "service unavailable"
}
],
"url": "http://edgex-core-command:48082/api/v1/device/97dcd3b2-f4f1-4a1a-9520-2ff62c697945/command/1bc520ef-a9a4-43c7-8098-dcc5faea9ea1"
},
"put": {
"path": "/api/v1/device/{deviceId}/RandomValue_Bool",
"parameterNames": [
"RandomValue_Bool",
"EnableRandomization_Bool"
],
"url": "http://edgex-core-command:48082/api/v1/device/97dcd3b2-f4f1-4a1a-9520-2ff62c697945/command/1bc520ef-a9a4-43c7-8098-dcc5faea9ea1"
}
}
]
},
]

这是我的主要颤振代码：

import 'dart:convert';
import 'package:flutter/material.dart';
import 'GET.dart';
import 'Device.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
build(context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'My Http App',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyListScreen(),
);
}
}
class MyListScreen extends StatefulWidget {
@override
createState() => _MyListScreenState();
}
class _MyListScreenState extends State {
var device = new List<Device>();
_getDevice() {
GET.getDevice().then((response) {
setState(() {
Iterable list = json.decode(response.body);
device = list.map((model) => Device.fromJson(model)).toList();
});
});
}
initState() {
super.initState();
_getDevice();
}
dispose() {
super.dispose();
}
@override
build(context) {
return Scaffold(
appBar: AppBar(
title: Text("Device List"),
),
body: ListView.builder(
itemCount: device.length,
itemBuilder: (context, index) {
return ListTile(title: Text("Num $index "+device[index].id));
},
));
}
}

这是我的设备类：

class Device {
//String 
String id;
String name;
//String commands;
Device(String id, String name) {
this.id = id;
this.name = name;
//this.commands = commands; 
//this.email = email;
}
Device.fromJson(Map json)
: id = json['id'],
name = json['name'];
// commands = json['commands'];
//['commands'][0]['name'], // marche
//email = json['email'];
Map toJson() {
return {'id': id, 'name': name};
}
}

Answer 1

你可以用下面的类强制转换json，并使用device[index].command获取设备的命令

class Device {
String id;
String name;
String adminState;
String operatingState;
int lastConnected;
int lastReported;
List<String> labels;
Null location;
List<Commands> commands;
Device(
{this.id,
this.name,
this.adminState,
this.operatingState,
this.lastConnected,
this.lastReported,
this.labels,
this.location,
this.commands});
Device.fromJson(Map<String, dynamic> json) {
id = json['id'];
name = json['name'];
adminState = json['adminState'];
operatingState = json['operatingState'];
lastConnected = json['lastConnected'];
lastReported = json['lastReported'];
labels = json['labels'].cast<String>();
location = json['location'];
if (json['commands'] != null) {
commands = new List<Commands>();
json['commands'].forEach((v) {
commands.add(new Commands.fromJson(v));
});
}
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['id'] = this.id;
data['name'] = this.name;
data['adminState'] = this.adminState;
data['operatingState'] = this.operatingState;
data['lastConnected'] = this.lastConnected;
data['lastReported'] = this.lastReported;
data['labels'] = this.labels;
data['location'] = this.location;
if (this.commands != null) {
data['commands'] = this.commands.map((v) => v.toJson()).toList();
}
return data;
}
}
class Commands {
int created;
int modified;
String id;
String name;
Get get;
Put put;
Commands(
{this.created, this.modified, this.id, this.name, this.get, this.put});
Commands.fromJson(Map<String, dynamic> json) {
created = json['created'];
modified = json['modified'];
id = json['id'];
name = json['name'];
get = json['get'] != null ? new Get.fromJson(json['get']) : null;
put = json['put'] != null ? new Put.fromJson(json['put']) : null;
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['created'] = this.created;
data['modified'] = this.modified;
data['id'] = this.id;
data['name'] = this.name;
if (this.get != null) {
data['get'] = this.get.toJson();
}
if (this.put != null) {
data['put'] = this.put.toJson();
}
return data;
}
}
class Get {
String path;
List<Responses> responses;
String url;
Get({this.path, this.responses, this.url});
Get.fromJson(Map<String, dynamic> json) {
path = json['path'];
if (json['responses'] != null) {
responses = new List<Responses>();
json['responses'].forEach((v) {
responses.add(new Responses.fromJson(v));
});
}
url = json['url'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['path'] = this.path;
if (this.responses != null) {
data['responses'] = this.responses.map((v) => v.toJson()).toList();
}
data['url'] = this.url;
return data;
}
}
class Responses {
String code;
String description;
Responses({this.code, this.description});
Responses.fromJson(Map<String, dynamic> json) {
code = json['code'];
description = json['description'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['code'] = this.code;
data['description'] = this.description;
return data;
}
}
class Put {
String path;
List<String> parameterNames;
String url;
Put({this.path, this.parameterNames, this.url});
Put.fromJson(Map<String, dynamic> json) {
path = json['path'];
parameterNames = json['parameterNames'].cast<String>();
url = json['url'];
}
Map<String, dynamic> toJson() {
final Map<String, dynamic> data = new Map<String, dynamic>();
data['path'] = this.path;
data['parameterNames'] = this.parameterNames;
data['url'] = this.url;
return data;
}
}