Question

我在这里遇到一个小问题。代码看起来没问题，但Application没有绑定我在WebAPI数据库中插入的正确列表。

我期望实现的目标：

跨平台的Listview，在这种情况下，我在Android中测试，它列出了WebAPI代码中的所有数据，如下所示：

这是WebAPI上列出的Json文件

[{"Id":1,"BusinessName":"La ventana","BusinessFantasyName":"La Ventana","BusinessArea":"Restaurante","BusinessSpecificArea":"Pizzaria","Country":"Brasil","State":"RS","City":"Rio Grande","Adress":"Av Rio Grande","Neighbourhood":"Cassino","Number":"134","Complement":"Casa","Latitude":-32.1853837,"Longitude":-52.1582284,"DateOfReg":"26/12/2017","DateOfMod":"26/12/2017","BusinessStatus":"Ativo","RegisteredBy":"Daniel Serrão"},{"Id":2,"BusinessName":"Supermercado Granabara - Cassino","BusinessFantasyName":"Supermercado Granabara - Cassino","BusinessArea":"Supermercados","BusinessSpecificArea":"Bens e Consumo","Country":"Brasil","State":"RS","City":"Rio Grande","Adress":"Av Rio Grande","Neighbourhood":"Cassino","Number":"150","Complement":"NA","Latitude":-32.1845922,"Longitude":-52.1591549,"DateOfReg":"26/12/2017","DateOfMod":"26/12/2017","BusinessStatus":"Ativo","RegisteredBy":"Daniel Serrão"}]

以下是咨询此WEBAPI的代码：

namespace Icquire.RestClient
{ public class RestClient<T> 
{
private const string WebServiceUrl = "http://localhost:58173/api/BusinessRegs/";

    public async Task<List<T>> GetAsync()
    {
        var httpClient = new HttpClient();
        var json = await httpClient.GetStringAsync(string.Format(WebServiceUrl));
        var BusinessReg = JsonConvert.DeserializeObject<List<T>>(json);
        return BusinessReg;
    }

    public async Task<bool> PostAsync(T t)
    {
        var httpClient = new HttpClient();
        var json = JsonConvert.SerializeObject(t);
        HttpContent httpContent = new StringContent(json);
        httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
        var result = await httpClient.PostAsync(WebServiceUrl, httpContent);
        return result.IsSuccessStatusCode;
    }

    public async Task<bool> PutAsync(int Id, T t)
    {
        var httpClient = new HttpClient();
        var json = JsonConvert.SerializeObject(t);
        HttpContent httpContent = new StringContent(json);
        httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
        var result = await httpClient.PostAsync(WebServiceUrl + Id, httpContent);
        return result.IsSuccessStatusCode;
    }

    public async Task<bool> DeleteAsync(int Id, T t)
    {
        var httpClient = new HttpClient();
        var response = await httpClient.DeleteAsync(WebServiceUrl + Id);
        return response.IsSuccessStatusCode;           
    }



}}

以下是内部服务的代码：

namespace Icquire.Services

{ public class BusinessRegServices
{ public async Task<List<BusinessReg>> GetBusinessRegAsync()

    {
        RestClient<BusinessReg> restClient = new RestClient<BusinessReg>();
        var BusinessRegList = await restClient.GetAsync();
        return BusinessRegList;
    }
}

}

以下是查看数据的代码：

namespace Icquire.ViewModel
{ public class BusinessRegView : INotifyPropertyChanged
{
    private List<BusinessReg> _BusinessRegList
    {
        get { return _BusinessRegList; }
        set
        {
            _BusinessRegList = value;
            OnPropertyChanged();
        }
    }


    public List<BusinessReg> BusinessRegList { get; set; }


    public BusinessRegView()
    {
        InitializeDataAsync();
    }

    private async Task InitializeDataAsync()
    {
        var businessRegServices = new BusinessRegServices();

        BusinessRegList = await businessRegServices.GetBusinessRegAsync();
    }

    public event PropertyChangedEventHandler PropertyChanged;

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

}

这是在contentPage中的My ListView：

 <ListView ItemsSource="{Binding BusinessRegList}" HasUnevenRows="True" >
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <StackLayout Orientation ="Vertical">
                            <Label TextColor="Silver" Text="{Binding BusinessName}"/>
                            <Label TextColor="Silver" Text="{Binding Adress}"/>
                            <Label TextColor="Silver" Text="{Binding Number}"/>
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

问题在于，使用上面的代码，ListView中的Binding返回空白。由于Json正在正确生成，我认为问题出在咨询到Json文件上。或者在服务代码中。有没有人有线索？

提前致谢... 丹尼尔。

Answer 1

假设您的服务调用实际上正在返回数据并且绑定设置正确。

您的财产声明不正确，应该是：

private List<BusinessReg> _BusinessRegList;

public List<BusinessReg> BusinessRegList
{
  get { return _BusinessRegList; }
  set
  {
     _BusinessRegList = value;
     OnPropertyChanged();
   }
}

更多信息可在Properties (C# Programming Guide)中找到。

通过C＃ListView应用程序使用JSON rest API进行Web API咨询 - Android返回空白

1 个答案: