小编Asy*_*yan的帖子

我目前有一个用户的个人资料页面，其中显示了他们的出生日期和其他详细信息。但是我打算通过计算今天的日期和从用户那里获得的出生日期之间的差值来找到他们生日前的日子。

用户的出生日期

这是使用intl包获得的今天的日期。

今天的日期

I/flutter ( 5557): 09-10-2018

我现在面临的问题是，如何计算这两个日期的天数差异？

是否有任何特定的配方或包装可供我检查？

我目前正在构建一个应用程序，以通过api读取数据，并且试图从JSON Placeholder解析JSON api。

我为用户创建了一个模型类（users_future_model.dart）：

class Users {
  final int userID;
  final String name;
  final String username;
  final String email;
  final Address address;

  Users({this.userID, this.name, this.username, this.email, this.address});

  factory Users.fromJson(Map<String, dynamic> usersjson)=> Users(
      userID: usersjson["id"],
      name: usersjson["name"],
      username: usersjson["username"],
      email: usersjson["email"],
      address: Address.fromJson(usersjson["address"])
  );
}

class Address{

  final String street;
  final String suite;
  final String city;
  final String zipcode;

  Address({this.street, this.suite, this.city, this.zipcode});

  factory Address.fromJson(Map<String, dynamic> addjson){

    return Address(
      street: addjson["street"],
      suite:  addjson["suite"],
      city: addjson["city"],
      zipcode: addjson["zipcode"]
    );
  }
}

这是将json读取到小部件中的main.dart： …

我在Flutter中有一个Json解析项目，Json如下：

{
  "Dependents":[
      {
        "Name": "Kim",
        "Relationship": "Parent",
        "Entitlements": [
            {
              "GP": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            },
            {
              "OPS": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            },
            {
              "IP": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            },
            {
              "Dental": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            },
            {
              "Optical": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            },
            {
              "Maternity": {
                "Entitlement": "10000",
                "Utilisation": "500",
                "Balance": "9500"
              }
            }
        ]
      },
      {
        "Name": …

我做了一个应用程序来显示一个州的医院列表.

这是Main.dart

import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher.dart';
import 'dart:async' show Future;
import 'package:flutter/services.dart' show rootBundle;
import 'dart:convert';
import 'package:emas_app/model/accounts_model.dart';

Future<String> _loadAsset() async{
  return await rootBundle.loadString('Assets/accounts.json');
}

Future<Accounts> loadAccounts() async{

  final response = await _loadAsset();
  final jsonResponse = json.decode(response);

  Accounts accounts = new Accounts.fromJson(jsonResponse);

  return accounts;
}

class ProviderList extends StatefulWidget {

  @override
  ListState createState() {
    return new ListState();
  }
}

class ListState extends State<ProviderList> {

  @override
  Widget build(BuildContext context) {

    Widget newbody = new ExpansionTile(
        title: new Text("State Name"),
        children: …

我目前有一个应用程序可以通过 JSON 提取提供者列表。

这是 JSON 文件。

医院.json

{
"Johor": [
    {
      "Name": "KLINIK TAJ (MUAR)",
      "TPA Customer ID": "1168",
      "Organization Type": "Clinic",
      "Organization Subtype": "GP",
      "Street (Billing)": "35a, jalan abdullah ",
      "City (Billing)": "muar",
      "Postal Code (Billing)": "84000",
      "State (Billing)": "Johor",
      "Country (Billing)": "Malaysia",
      "Coordinates": {
        "Latitude": "2.041875",
        "Longitude": "102.568235"
      }
    },
    {
      "Name": "KLINIK TAJ (PAGOH)",
      "TPA Customer ID": "1169",
      "Organization Type": "Clinic",
      "Organization Subtype": "GP",
      "Street (Billing)": "100 Main Road Pagoh",
      "City (Billing)": "Muar",
      "Postal Code (Billing)": "84600", …

我目前有一个简单的 API，但是如果不重新启动整个应用程序，我的 flutter 小部件就无法检测到 API 中发生的变化。

该 API 是在https://www.mockable.io/上作为测试 API 制作的。我设法使用StreamBuilder从这个 API 读取。每当我在 API 中更新它们的值时，它仍然不会更改小部件中的值。

默认 JSON

{
 "id": "123",
 "token": "1token",
 "status": "Valid"
}

值更改后

{
 "id": "123",
 "token": "1token",
 "status": "Not Valid"
}

我的 StreamBuilder 代码

import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:convert';
import 'package:http/http.dart' as http;

final String url = "http://demo2722084.mockable.io/user";

class StreamPage extends StatefulWidget {

  @override
  StreamPageState createState() {
    return new StreamPageState();
  }
}

class StreamPageState extends State<StreamPage> {

  StreamController _userController;

  Future fetchUser() …

我有一个 JSON 应用程序调用用户，但在处理空地图时遇到问题。

这是 Json 文件。

会员信息.json

{
"Dependents": [
    {
      "Name": "Kim",
      "Relationship": "Parent",
      "Entitlements": {
        "GP": {
          "Entitlement": "10000",
          "Utilisation": "500",
          "Balance": "9500"
        },
        "OPS": {
          "Entitlement": "10000",
          "Utilisation": "500",
          "Balance": "9500"
        },
        "IP": {
          "Entitlement": "50000",
          "Utilisation": "17000",
          "Balance": "33000"
        }
      }
    },
    {
      "Name": "Tim",
      "Relationship": "Spouse",
      "Entitlements": {
        "GP": {
          "Entitlement": "10000",
          "Utilisation": "500",
          "Balance": "9500"
        },
        "OPS": {
          "Entitlement": "10000",
          "Utilisation": "500",
          "Balance": "9500"
        },
        "IP": {

        }
      }
    }
  ]
}

dart文件如下：

import …

下面是我的模型类：

crm_dependent_list_model.dart（模型类）

import \'crm_dep_entitlement_model.dart\';\n\nclass DependantModel{\n\n  String name;\n  String relationship;\n  EntitlementsModel entitlements;\n\n  DependantModel({this.name, this.relationship, this.entitlements});\n\n  factory DependantModel.fromJson(Map depjson){\n\n    return DependantModel(\n      name: depjson["Name"].toString(),\n      relationship: depjson["Relationship"].toString(),\n      entitlements: EntitlementsModel.fromJson(depjson["Entitlements"])\n    );\n  }\n}\n

这是位于DependantModel 类内的EntitlementsModel

class EntitlementsModel{\n\n  final GP gp;\n  final OPS ops;\n  final IP ip;\n  final Dental dental;\n  final Optical optical;\n  final EHS ehs;\n\n  EntitlementsModel({this.gp, this.ops, this.ip, this.dental, this.optical, this.ehs});\n\n  factory EntitlementsModel.fromJson(Map ejson){\n\n    return EntitlementsModel(\n\n      gp: GP.fromJson(ejson["GP"]),\n      ops: OPS.fromJson(ejson["OPS"]),\n      ip: IP.fromJson(ejson["IP"]),\n      dental: Dental.fromJson(ejson["Dental"]),\n      optical: Optical.fromJson(ejson["Optical"]),\n      ehs: EHS.fromJson(ejson["EHS"])\n …