Question

我正在尝试从我的Web API获取数据并将其显示在我的ListView上。当我单击按钮检索数据时，它返回我并且错误：

[0:] Binding: MobileUI.Models.RootObject can not be converted to type 'System.Collections.IEnumerable'

所以我在Deserilization上创建了断点，它正确地返回了数据，但它没有显示在ListView上。

这是我的代码： -

ApiServices类中的GetUserAsync

public async Task<RootObject> GetUserAsync(string accessToken)
{
    var client = new HttpClient();

    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

    var json = await client.GetStringAsync("http://weburl/testrun/api/services/app/user/GetRoles");

    var users = JsonConvert.DeserializeObject<RootObject>(json);

    return users;

}

UserViewModel

private readonly ApiServices _apiServices = new ApiServices();

private RootObject _users;
public RootObject Users
{
    get { return _users; }
    set
    {
        _users = value;
        OnPropertyChanged();
    }
}
public ICommand GetUsersCommand
{
    get
    {
        return new Command(async () =>
        {
            var accessToken = Settings.AccessToken;
            Users = await _apiServices.GetUserAsync(accessToken);
        });
    }
}

public event PropertyChangedEventHandler PropertyChanged;

protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

}

JSON回复

{
    "result": {
        "items": [
            {
                "name": "Admin",
                "displayName": "Admin",
                "description": null,
                "isStatic": true,
                "permissions": [
                    "Pages.Users",
                    "Pages.Roles",
                    "Pages.Tenants"
                ],
                "id": 1
            },
            {
                "name": "Tenants",
                "displayName": "Tenants",
                "description": "",
                "isStatic": false,
                "permissions": [
                    "Pages.Tenants",
                    "Pages.Users"
                ],
                "id": 12
            },
            {
                "name": "Landlord",
                "displayName": "Landlord",
                "description": "",
                "isStatic": false,
                "permissions": [
                    "Pages.Tenants",
                    "Pages.Property",
                    "Pages.Payment",
                    "Pages.Feedback",
                    "Pages.Document",
                    "Pages.LandLord",
                    "Pages.Users"
                ],
                "id": 14
            },
            {
                "name": "User",
                "displayName": "Users",
                "description": "",
                "isStatic": false,
                "permissions": [
                    "Pages.Property",
                    "Pages.Payment",
                    "Pages.Feedback",
                    "Pages.Document"
                ],
                "id": 20
            }
        ]
    },
    "targetUrl": null,
    "success": true,
    "error": null,
    "unAuthorizedRequest": false,
    "__abp": true
}

XAML代码

<Button Command="{Binding GetUsersCommand}"
        Text="Get All User Roles"
        TextColor="White"
        FontSize="20"
        BackgroundColor="DodgerBlue"/>

<ListView ItemsSource="{Binding Users}"
          HasUnevenRows="True">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <StackLayout Padding="0,10">
                    <Label Text="{Binding result}" />
                    <Label Text="{Binding success}" />
                    <Label Text="{Binding error}" />
                    <Label Text="{Binding displayName}" />
                    <Label Text="{Binding isStatic}" />
                </StackLayout>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>

</ListView>

注意：如果我将其转换为List，则会出现以下错误

未处理的例外：

Newtonsoft.Json.JsonSerializationException：无法反序列化   当前的JSON对象（例如{“name”：“value”}）到类型中   'System.Collections.Generic.List`1 [MobileUI.Models.RootObject]'   因为该类型需要一个JSON数组（例如[1,2,3]）来反序列化   正确。要修复此错误，请将JSON更改为JSON数组   （例如[1,2,3]）或更改反序列化类型以使其正常   .NET类型（例如，不是整数的基本类型，不是集合   类似于数组或List的类型，可以从JSON反序列化   宾语。 JsonObjectAttribute也可以添加到类型中以强制它   从JSON对象反序列化。路径'结果'，第1行，第10位。

编辑1：添加转换后的JSON响应

public class Item
{
    public string name { get; set; }
    public string displayName { get; set; }
    public string description { get; set; }
    public bool isStatic { get; set; }
    public List<string> permissions { get; set; }
    public int id { get; set; }
}

public class Result
{
    public List<Item> items { get; set; }
}

public class RootObject
{
    public Result result { get; set; }
    public object targetUrl { get; set; }
    public bool success { get; set; }
    public object error { get; set; }
    public bool unAuthorizedRequest { get; set; }
    public bool __abp { get; set; }
}

Answer 1

用此

替换您的UserViewModel

private readonly ApiServices _apiServices = new ApiServices();

private ObservableCollection<Item>  _users;
public ObservableCollection<Item>  Users
{
    get { return _users; }
    set
    {
        _users = value;
        OnPropertyChanged();
    }
}
public ICommand GetUsersCommand
{
    get
    {
        return new Command(async () =>
        {
            var accessToken = Settings.AccessToken;
            var user_result = await _apiServices.GetUserAsync(accessToken);
            if(user_result!=null)
            {
                 Users =new ObservableCollection<Item>(user_result.result.items);
            }
        });
    }
}

public event PropertyChangedEventHandler PropertyChanged;

protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

Xamarin.Forms [0：]绑定：MobileUI.Models.RootObject无法转换为'System.Collections.IEnumerable'类型

1 个答案: