linq绑定下拉列表，combobox中增加listitem的方法，增加“请选择”

第一步：自定义一个类ListItem

 

public class ListItem
    {
        private string text = string.Empty;
        private string value = string.Empty;
        public ListItem(string Text, string Value)
        {
            text = Text;
            value = Value;
        }
        public override string ToString()
        {
            return this.value;
        }
        public string Text
        {
            get
            {
                return this.text;
            }
            set
            {
                this.text = value;
            }
        }
        public string Value
        {
            get
            {
                return this.value;
            }
            set
            {
                this.value = value;
            }
        }
    }

第二步：采用linq查询数据并绑定到combobox，解决很多人想问的增加默认选项“请选择”的问题

 

 private void BindRadioType()
        {
            cmbRadioType.DataSource = null;
            cmbRadioType.Items.Clear();
            using (DCDataBaseDataContext db = new DCDataBaseDataContext())
            {
                var query = (from c in db.Items_RadioType
                            select new{c.ItemName,c.Id}
                            ).ToList();
                List<ListItem> items = new List<ListItem>();
                foreach (var temp in query)
                {
                    items.Add(new ListItem(temp.ItemName,temp.Id.ToString()));
                }
                items.Insert(0, new ListItem("请选择", "-1"));
                cmbRadioType.DataSource = items;
                cmbRadioType.DisplayMember = "Text";
                cmbRadioType.ValueMember = "Value";               
            }         
        }