急求关于propertygrid下拉框问题的解决办法。。。在线等

chaomeier 2010-04-29 02:33:15

下面代码我是用于测试该控件下拉框的实现。我遇到的问题是，当原数据是string类型时，选择下拉框选项，不会出现问题，但当原数据是int类型时，会出现“类型“System.String”的对象无法转换为类型“System.Int32”。”的错误提示。

我重载了ConvertFrom函数，但只能修改StandardValuesCollection集合中的一个元素（例子里总共是8个元素：0，1，2。。。），不会改全部元素。请高手指点，急！！！（新手，分数不多，笑纳）



namespace attributetest

{

    

    public partial class Form1 : Form

    {

        

        public Form1()

        {

            InitializeComponent();

        }



        private void Form1_Load(object sender, EventArgs e)

        {



            propertyGrid1.SelectedObject = new MyObject();



        }



    }

    public class MyConverter : ExpandableObjectConverter

    {



        public override bool GetStandardValuesSupported(ITypeDescriptorContext context)

        {



            return true;



        }



        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)

        {



            return true;



        }



        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)

        {

            



            ListAttribute lst = (ListAttribute)context.PropertyDescriptor.Attributes[typeof(ListAttribute)];

            

            StandardValuesCollection vals = new TypeConverter.StandardValuesCollection(lst.obcollection);

            

            return vals;



        }





        public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)

        {

            return true;

        }



        public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)

        {

            return base.ConvertTo(context, culture, value, destinationType);            



        }

        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)

        {

            return true;

        }



        public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)

        {

                return value;                    



        }



       



    }

    public class ListAttribute : Attribute

    {



        

        public object[] obcollection;



        public ListAttribute()

        {              



        }

        public ListAttribute(string str)

        {

            

            int i=0;

            string conn="Data Source=(local);Initial Catalog=yj;Integrated Security=True;Pooling=False";

            SQLTools sql=new SQLTools(conn);

            DataTable dt=sql.executeQuery(str);

            obcollection=new object[dt.Rows.Count];

            MessageBox.Show(dt.Rows[0][0].GetType().ToString());

            foreach(DataRow row in dt.Rows)

            {

                

                obcollection[i]=row[0];

                i++;

            }

        }



    }

    public class MyObject

    {

        

        private int id;

        [TypeConverter(typeof(MyConverter)), ListAttribute("select bdz_id from dds_biandianzhan")]

        public int ID

        {



            get

            {



                return id;



            }



            set

            {



                id = value;



            }



        }



        private string code;



        public string Code

        {



            get

            {



                return code;



            }



            set

            {



                code = value;



            }



        }



        private string name;

                

        [TypeConverter(typeof(MyConverter)), ListAttribute("select bdz_name from dds_biandianzhan")]

        public string Name

        {



            get

            {



                return name;



            }



            set

            {



                name = value;



            }



        }



        public MyObject()

        {



            this.id = 0;



            this.code = "小旺财";



            this.name = "小强";

            



        }



    }



}