【发布时间】：2019-01-04 02:14:27
【问题描述】：
到目前为止，我可以将值传递给另一个视图，但问题是我不知道如何使用 MVVM 来执行此操作。我尝试了文档和教程仍然没有运气。我怎样才能做到这一点？
我的项目流程：
- 用户将登录，当用户提供正确的信息时，它将返回一个 JSON 数组，其中包含用户的 ContactID。
- 这个 ContactID 现在被传递到另一个视图。它将用于将服务器同步到本地数据库，反之亦然
我的问题是：
1.如何使用 MVVM 将数据传递到其他视图？
2.如何检查数据是否正确传递？
HTTPWebRequest 的输出：
[{"ContactID":"1"}]
我的代码：
LoginPageViewModel.cs
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Net;
using System.Text;
using System.Windows.Input;
using TBSMobileApplication.Data;
using TBSMobileApplication.View;
using Xamarin.Essentials;
using Xamarin.Forms;
namespace TBSMobileApplication.ViewModel
{
public class LoginPageViewModel : INotifyPropertyChanged
{
void OnPropertyChanged(string PropertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
}
public string username;
public string password;
public string Username
{
get { return username; }
set
{
username = value;
OnPropertyChanged(nameof(Username));
}
}
public string Password
{
get { return password; }
set
{
password = value;
OnPropertyChanged(nameof(Password));
}
}
public class LoggedInUser
{
public int ContactID { get; set; }
}
public ICommand LoginCommand { get; set; }
public LoginPageViewModel()
{
LoginCommand = new Command(OnLogin);
}
public void OnLogin()
{
if (string.IsNullOrEmpty(Username) || string.IsNullOrEmpty(Password))
{
MessagingCenter.Send(this, "Login Alert", Username);
}
else
{
var current = Connectivity.NetworkAccess;
if (current == NetworkAccess.Internet)
{
var link = "http://192.168.1.25:7777/TBS/test.php?User=" + Username + "&Password=" + Password;
var request = HttpWebRequest.Create(string.Format(@link));
request.ContentType = "application/json";
request.Method = "GET";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
if (response.StatusCode != HttpStatusCode.OK)
{
Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
}
else
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
var content = reader.ReadToEnd();
if (content.Equals("[]") || string.IsNullOrWhiteSpace(content) || string.IsNullOrEmpty(content))
{
MessagingCenter.Send(this, "Http", Username);
}
else
{
var result = JsonConvert.DeserializeObject<List<LoggedInUser>>(content);
var contactId = result[0].ContactID;
Application.Current.MainPage.Navigation.PushAsync(new DatabaseSyncPage(contactId), true);
}
}
}
}
}
else
{
MessagingCenter.Send(this, "Not Connected", Username);
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
}
DatabaseSyncPage.xaml.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace TBSMobileApplication.View
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class DatabaseSyncPage : ContentPage
{
public DatabaseSyncPage (int contanctId)
{
InitializeComponent ();
}
}
}
【问题讨论】：
-
@mvermef 我只想回答如何在 mvvm 中获取传递的数据
标签： rest xamarin mvvm xamarin.forms