C# 如何将值从实体层传递到表示层

我试图在点击gridview中的linkbutton时填充Person对象，然后获取其相关数据并显示在模式中的文本框中。我能够获取数据并将其传递给Person对象，但是，当我填充模态控件时，Person对象在所有属性上返回null

您知道如何在不调用Person objPerson=new Person（）的情况下将Person对象的值传递给textbox控件吗

先谢谢你

实体：

public class Person
{
    public int PersonID { get; set; }
    public string Firstname { get; set; }
    public string Lastname { get; set; }
}

数据层：

public DataTable SelectQueryProc(String _storedProc, SqlParameter[] sqlParameter)
{
    DataTable t = new DataTable();

    try
    {
        using (SqlConnection sqlConnection = new SqlConnection(CommonEntity.ConnectionString))
        {
            sqlConnection.Open();
            using (SqlDataAdapter adapter = new SqlDataAdapter(_storedProc, sqlConnection))
            {
                adapter.SelectCommand.CommandType = CommandType.StoredProcedure;
                adapter.SelectCommand.Parameters.AddRange(sqlParameter);
                adapter.Fill(t);
            }
        }
    }
    catch (SqlException e)
    {
        throw new SystemException(e.ToString());
    }
    finally
    {

    }
    return t;
}

public List<Person>GetPersonSingleByPersonID(string personID)
{
    List<Person> objPerson = new List<Person>();
    DataTable dt = new DataTable();

    SqlParameter[] sqlParam = new SqlParameter[1];
    sqlParam[0] = new SqlParameter("@PersonID", SqlDbType.VarChar);
    sqlParam[0].Value = personID;

    CommonDAL commonDAL = new CommonDAL();
    dt = commonDAL.SelectQueryProc("GetPersonSingleByPersonID", sqlParam);

    foreach (DataRow dr in dt.Rows)
    {
        objPerson.Add(new Person()
        {
            PersonID = dr["PersonID"].ToString(),
            Firstname = dr["Firstname"].ToString(),
            Lastname = dr["Lastname"].ToString()            
        });
    }
    return objPerson;
}

---

您尝试从空的Person对象获取值，而不是从DAL获取值。所以你的方法应该是这样的

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            switch (e.CommandName)
            {
                case "click":
                    {
                        // Populate Person Details                        
                        PersonBL objPersonBL = new PersonBL();
                        var objPerson = objPersonBL.GetPersonSingleByPersonID(e.CommandArgument.ToString());

                        //Person objPerson = new Person();
                        if (objPerson.Count != 0)
                        {
                            txtPersonID.Text = objPerson[0].PersonID;
                            txtFirstname.Text = objPerson[0].Firstname;
                            txtLastname.Text = objPerson[0].Lastname;
                            break;
                        }
                    }
                default:
                    break;
            }
        }

---

很明显，您正在将新创建的对象（尚未填充）值分配给文本框。 您的代码应该是：

PersonBL objPersonBL = new PersonBL();
Person objPerson = objPersonBL.GetPersonSingleByPersonID(e.CommandArgument.ToString());
 if (objPerson.Count != 0)
{
txtPersonID.Text = objPerson.PersonID;
txtFirstname.Text = objPerson.Firstname;
txtLastname.Text = objPerson.Lastname;
}

---

您是否调试了此代码，并在DAL中填充人员时进行了演示？是的，已填充。我认为演示文稿中的new Person（）会导致文本框出现空值Person构造函数是否将Firstname、PersonID和Lastname设置为

string.Empty

，或者将它们保留为默认值

null

？public int PersonID{get；set；}我认为默认值为空

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            switch (e.CommandName)
            {
                case "click":
                    {
                        // Populate Person Details                        
                        PersonBL objPersonBL = new PersonBL();
                        var objPerson = objPersonBL.GetPersonSingleByPersonID(e.CommandArgument.ToString());

                        //Person objPerson = new Person();
                        if (objPerson.Count != 0)
                        {
                            txtPersonID.Text = objPerson[0].PersonID;
                            txtFirstname.Text = objPerson[0].Firstname;
                            txtLastname.Text = objPerson[0].Lastname;
                            break;
                        }
                    }
                default:
                    break;
            }
        }

PersonBL objPersonBL = new PersonBL();
Person objPerson = objPersonBL.GetPersonSingleByPersonID(e.CommandArgument.ToString());
 if (objPerson.Count != 0)
{
txtPersonID.Text = objPerson.PersonID;
txtFirstname.Text = objPerson.Firstname;
txtLastname.Text = objPerson.Lastname;
}