无法将类型“MyAriticket.Model.CityInfo”隐式转换为“System.Collections.Generic.IList<MyAriticket.Model.CityInfo>”。存在一个显式转换(是否缺少强制转换?)数据访问层
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
string sql = " select * from CityInfo where CityId = '" + id + "'";
SqlDataReader reader = DBHelper.GetReader(sql);
if (reader.Read())
{
CityInfo item = new CityInfo();
item.CityId = Convert.ToInt32(reader["CityId"]);
item.CityName = Convert.ToString(reader["CityName"]);
item.ProvinceId = Convert.ToString(reader["ProvinceId"]);
reader.Close();
return item;
}
else
{
reader.Close();
return null;
}
}业务逻辑层
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
return CityInfoService.GetByCityId(id);
}
表示层
//查询
protected void BtnGet_Click(object sender, EventArgs e)
{
////出发地
int id = Convert.ToInt32(this.ddlFromCity.SelectedValue);
IList<CityInfo> item = CityInfoManager.GetByCityId(id);
}
那位帮我看看
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
string sql = " select * from CityInfo where CityId = '" + id + "'";
SqlDataReader reader = DBHelper.GetReader(sql);
if (reader.Read())
{
CityInfo item = new CityInfo();
item.CityId = Convert.ToInt32(reader["CityId"]);
item.CityName = Convert.ToString(reader["CityName"]);
item.ProvinceId = Convert.ToString(reader["ProvinceId"]);
reader.Close();
return item;
}
else
{
reader.Close();
return null;
}
}业务逻辑层
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
return CityInfoService.GetByCityId(id);
}
表示层
//查询
protected void BtnGet_Click(object sender, EventArgs e)
{
////出发地
int id = Convert.ToInt32(this.ddlFromCity.SelectedValue);
IList<CityInfo> item = CityInfoManager.GetByCityId(id);
}
那位帮我看看
“System.Collections.Generic.IList<MyAriticket.Model.CityInfo>”隐式转换为“System.Collections.Generic.IList<CityInfo>”。存在一个显式转换(是否缺少强制转换?) 数据访问层
//根据ProvinceId查询地区信息
public static IList<CityInfo> GetCityInfoById(int id)
{
IList<CityInfo> list = new List<CityInfo>();
string sql = " select * from CityInfo where ProvinceId = '" + id + "'";
DataTable table = DBHelper.GetDataSet(sql);
foreach (DataRow row in table.Rows)
{
CityInfo item = new CityInfo();
item.CityId = Convert.ToInt32(row["CityId"]);
item.CityName = Convert.ToString(row["CityName"]);
item.ProvinceId = Convert.ToString(row["ProvinceId"]);
list.Add(item);
}
return list;
}
业务逻辑层
//根据ID查询地区信息
public static IList<CityInfo> GetCityInfoById(int id)
{
return CityInfoService.GetCityInfoById(id);
}
表示层
//出发地
protected void ddlFromProvinceInfo_SelectedIndexChanged(object sender, EventArgs e)
{
int id = Convert.ToInt32(this.ddlFromProvinceInfo.SelectedValue);
IList<CityInfo> list = CityInfoManager.GetCityInfoById(id);
this.ddlFromCity.DataSource = list;
this.ddlFromCity.DataBind();
}
数据访问层
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
string sql = " select * from CityInfo where CityId = '" + id + "'";
SqlDataReader reader = DBHelper.GetReader(sql);
if (reader.Read())
{
CityInfo item = new CityInfo();
item.CityId = Convert.ToInt32(reader["CityId"]);
item.CityName = Convert.ToString(reader["CityName"]);
item.ProvinceId = Convert.ToString(reader["ProvinceId"]);
reader.Close();
return item;
}
else
{
reader.Close();
return null;
}
}业务逻辑层
//根据ID查询地区信息
public static CityInfo GetByCityId(int id)
{
return CityInfoService.GetByCityId(id);
}表示层
//查询
protected void BtnGet_Click(object sender, EventArgs e)
{
////出发地
int ids = Convert.ToInt32(this.ddlToCity.SelectedValue);
CityInfo num = CityInfoManager.GetByCityId(ids);
}
这个也不好用了
CityInfo这两个有什么区别?你定义了两种CityInfo?分别右键点这个类,查看定义看看这哪儿
他说"MyAriticket.Model.CityInfo"是IList<CityInfo>这里的
"CityInfo"是CityInfoManager.GetByCityId(ids); 的返回值类型
“System.Collections.Generic.IList<MyAriticket.Model.CityInfo>”隐式转换为“System.Collections.Generic.IList<CityInfo>”。存在一个显式转换(是否缺少强制转换?)
而不是类型没定义,
那么你这儿我还是怀疑定义了两个CityInfo了,用自动生成代码的工具或者linq to sql一类的东西么?