Question

我正在尝试从sql server检索数据然后绑定到xamarin表单条目我正在使用共享项目

登录后我的问题并打开新的内容页面（主页）有一个错误System.InvalidCastExeption：指定的强制转换无效然后我的主页面是空的。

这是代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using System.Data;
using System.Data.SqlClient;
namespace App10
{
    public partial class MainPage : ContentPage
    {          
        public MainPage()
        {
            InitializeComponent();
            //entry

            //connectionstring
            string serverIp = "192.168.43.16,1433";
            string username = "un";
            string password = "pass";
            string databaseName = "db";

            string dbConnectionString = string.Format("Data Source={0};User ID={1};Password={2};Database={3};", serverIp, username, password, databaseName);
            IDbConnection dbcon;
            using (dbcon = new SqlConnection(dbConnectionString))
            {
                try
                {
                    dbcon.Open();
                    using (IDbCommand dbcmd = dbcon.CreateCommand())
                    {
                        string sql =
                            "SELECT ADMITBED_ID,AdmittingNumber,FullName,RoomID,DaysofStay,LastCensusDate,LastTimeCensus " +
                            "FROM AdmittedWardRoomManagement WHERE Status = 'ADMITTED' AND FullName = 'Full Name'";
                        dbcmd.CommandText = sql;
                        using (IDataReader reader = dbcmd.ExecuteReader())
                        {
                            while (reader.Read())
                            {    
                                FullName.SetBinding(Label.TextProperty, "Name"); \\error i think here at bindings
                                string id = (string)reader["ADMITBED_ID"];
                                FullName.BindingContext = new { Name = id };
                            }
                        }
                    }
                }

                catch (Exception ex)
                {
                    DisplayAlert("Daily Census", Convert.ToString(ex), "OK");
                }
            }
        }
    }
}

Answer 1

我删除了这一行

FullName.SetBinding(Label.TextProperty, "Name");
string id = (string)reader["ADMITBED_ID"];
FullName.BindingContext = new { Name = id };

随着这个改变

string id = reader["ADMITBED_ID"].ToString();

Xamarin数据绑定错误System.InvalidCastExeption：指定的强制转换无效

1 个答案: