无法将json反序列化为ObservableCollection并绑定到Xamarin.Forms中的xaml

Question

我正在尝试将简单的json反序列化为ObservableCollection。当我为反序列化设置断点时似乎没有发生任何事情。该方法永远不会完成，也不会抛出错误。我能够获取json并转换为字符串，而不是反序列化为ObservableCollection。

我错过了什么吗？我已经查看了我可以找到的用于反序列化到对象的每个代码示例，但似乎无法使其工作。

这是我的Xamarin.Forms页面的代码。

public partial class Notification : ContentPage
{
    public Notification()
    {
        InitializeComponent();
        this.BindingContext = NotificationData();
    }

    public async Task NotificationData()
    {
        ObservableCollection<Alert> notification = await GetAlert();
        NotificationList.ItemsSource = notification;
    }
    public static async Task<ObservableCollection<Alert>> GetAlert()
    {
        string WPPosts = "https://www.url.com/alerts.json";
        HttpClient client = new HttpClient();
        var response = await client.GetAsync(WPPosts).ConfigureAwait(false);

        if (response != null)
        {
            ObservableCollection<Alert> data = new ObservableCollection<Alert>();
            string content = response.Content.ReadAsStringAsync().Result;
            //string content_sanitized = RemoveHTMLTags(content);
            data = JsonConvert.DeserializeObject<ObservableCollection<Alert>>(content);
            return data;
        }
        else { return null; }
    }
    public class Alert
    {
        public string title { get; set; }
        public string imgUrl { get; set; }
        public string content { get; set; }
    }

    public class RootObject
    {
        public List<Alert> alerts { get; set; }
    }
}

这是我的Xaml。

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" Title="News 
and Alerts" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
x:Class="JenksTrash.Notification" xmlns:local="clr-
namespace:JenksTrash" >
<ListView x:Name="NotificationList">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="1" />
                        <ColumnDefinition Width="7*" />
                    </Grid.ColumnDefinitions>
                        <Label Text="{Binding title}" FontAttributes="Bold" />
                        <Label Text="{Binding content}" FontAttributes="Bold" />
                    </Grid>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

任何理解这一点的帮助都会很棒。

Answer 1

Sub Vgbl() Dim IE As Object Dim n, Period1, Period2 As Double Dim MAPFREVI, VIDASEG, CS, Alianca, Brasilv, MapfreSeg, BrasilPrev, SEGUROS, TODAS, BrasilCap As Variant SEGUROS = "54" TODAS = "Todas" Period1 = Sheets("Capa").Cells(4, 3).Value Period2 = Sheets("Capa").Cells(5, 3).Value n = Sheets("Ramos").Cells(65, 4).Value Set IE = CreateObject("InternetExplorer.Application") IE.Navigate "http://www2.susep.gov.br/menuestatistica/SES/principal.aspx" IE.Visible = True While IE.Busy DoEvents Wend Application.Wait (Now + TimeValue("00:00:02")) 'seleciona as operações desejadas IE.document.getElementById("ctl00_ContentPlaceHolder1_edSelOp").Value = SEGUROS IE.document.getElementById("ctl00_ContentPlaceHolder1_btnConsultar").Click 'seleciona o periodo Application.Wait (Now + TimeValue("00:00:02")) Set ieDoc = IE.document ieDoc.getElementById("ctl00_ContentPlaceHolder1_edInicioPer").Value = Period1 ieDoc.getElementById("ctl00_ContentPlaceHolder1_edFimPer").Value = Period2 'seleciona as empresas IE.document.getElementById("ctl00_ContentPlaceHolder1_edEmpresas").SelectedIndex = TODAS 'seleciona os ramos Set objListbox = IE.document.getElementById("ctl00_ContentPlaceHolder1_edRamos") objListbox.Options(n).Selected = True n = Sheets("Ramos").Cells(66, 4).Value objListbox.Options(n).Selected = True n = Sheets("Ramos").Cells(67, 4).Value objListbox.Options(n).Selected = True End sub 嵌套在根对象下，因此您无法直接对其进行反序列化。

但是，你可以试试这个：

alerts

这可以帮助您理解问题：

您拥有的json与JObject.Parse(content) .SelectToken("alerts") .ToObject<ObservableCollection<Alert>>(); 类似，但您尝试将其反序列化为RootObjectWithNestedNumberList。显然，它不会起作用。