我正在开发.NET应用程序,但我遇到了问题。 我尝试使用Entity Framework从MySQL数据库填充列表框。 这是我的代码:
public MainForm()
{
InitializeComponent();
try
{
hospitaldbEntities context = new hospitaldbEntities();
PatientlistBoxId.DataSource = context.patients;
PatientlistBoxId.DisplayMember = "FirstName";
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
我附上解决方案资源管理器中的图片:
最后这是我的耐心课:
public partial class patient
{
public patient()
{
this.examinations = new HashSet<examination>();
this.diseases = new HashSet<disease>();
this.drugsensitivities = new HashSet<drugsensitivity>();
}
public int PatientID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public System.DateTime DateOfBirth { get; set; }
public string Gender { get; set; }
public string Address { get; set; }
public System.DateTime DateOfCreate { get; set; }
public string Category { get; set; }
public int CNP { get; set; }
public virtual ICollection<examination> examinations { get; set; }
public virtual ICollection<disease> diseases { get; set; }
public virtual ICollection<drugsensitivity> drugsensitivities { get; set; }
}
提前感谢您的帮助。
修改
当我尝试运行该应用程序时,它会抛出一个错误:
答案 0 :(得分:1)
你必须至少使用:
PatientlistBoxId.DataSource = context.patients.ToList();
考虑使用BindingList<T>
顺便说一句:
考虑不将实体类型用作ListBox的ItemType。
考虑使用using
上下文来处理您的上下文,这样可以更清楚地处理上下文的范围。
========== ==========
更多细节
//this class allows to separate the winform (equivalent to a view) from
//the data layer, you can see it as a ViewModel
public class FormNamePatient {
public Int32 Id { get; set;}
public String FirstName { get; set;}
public String LastName { get; set;}
}
private BindingList<FormNamePatient> _patients;
try {
//the using guarantees the disposing of the resources
//(avoiding memory link and so on)
using ( hospitaldbEntities context = new hospitaldbEntities() ) {
_patients = new BindindList<FormNamePatient>(
context.patients.Select(
x => new FormNamePatient {
Id = x.Id,
FirstName = x.FirstName,
LastName = x.LastName,
}).ToList() // this materialize the list
// in other (bad ?) words, this allows the list
//to live out of the context (<=> using)
);
}
PatientlistBoxId.DataSource ) = _patients;
//now if you alter (not erase, but edit, change...) _patients you
//update the control
PatientlistBoxId.DisplayMember = "FirstName";
} catch (Exception ex) {
Console.WriteLine(ex);
}