我正在尝试将数据库中的项目添加到列表中，而不是从aspx中静态添加它们。我创建了这个方法，虽然它编译，但它不会向我的下拉列表中添加任何列表项。这是一些代码，如果需要，我愿意提供更多代码。有问题的方法是addListItemsToPage（）。
C＃
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace EndophthalmitisDatabase {
public partial class DataEntry : System.Web.UI.Page {
protected void Page_Load(object sender, EventArgs e) {
addListItemsToPage();
}
protected void addListItemsToPage() {
EndophthalmitisDBDataContext dbContext = new EndophthalmitisDBDataContext();
for (int i=0; dbContext.Hospital_Datas.Count() < i; i++){
int id = dbContext.Hospital_Datas.ElementAt(i).HospitalID;
string str = dbContext.Hospital_Datas.ElementAt(i).Hospital_Name;
ListItem li = new ListItem();
li.Text = str;
li.Value = id.ToString();
hospitalDDL.Items.Add(li);
}
}
protected void submitEndoDataBtn_Click(object sender, EventArgs e)
{
using (EndophthalmitisDBDataContext dbContext = new EndophthalmitisDBDataContext()) {
Occurrence_Data occData = new Occurrence_Data
{
LastName = lastNameTB.Text,
FirstName = firstNameTB.Text,
MRN = int.Parse(mrnTB.Text),
DateOfOccurence = DateOfOccurenceCal.SelectedDate,
InterventionProcedureDone = int.Parse(InterventionDDL.SelectedValue),
PreOccurrencePhysician = int.Parse(InterventionSurgeonDDL.SelectedValue),
LabsSent = labsSentCB.Checked,
PrecipitatingCausePreviousSurgery = int.Parse(preCauseDDL.SelectedValue),
PostOccurrencePhysician = int.Parse(preSurgeonDDL.SelectedValue),
DateOfPreviousSurgery = datePrecipitatingCal.SelectedDate,
Hospital = int.Parse(hospitalDDL.SelectedValue),
AdditionalInformation = moreInfoTB.Text
};
lastNameTB.Text = "";
firstNameTB.Text = "";
mrnTB.Text = "";
labsSentCB.Checked = false;
moreInfoTB.Text = "";
dbContext.Occurrence_Datas.InsertOnSubmit(occData);
dbContext.SubmitChanges();
}
}
}
}
ASPX
<%@ Page Title="" Language="C#" MasterPageFile="~/MainSite.Master" AutoEventWireup="true" CodeBehind="DataEntry.aspx.cs" Inherits="EndophthalmitisDatabase.DataEntry" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="mainContent" runat="server">
<div class="formBox">
<p style="text-align: center">Please use the area below to enter Data.</p>
<div class = "dataEntryForm">
<form id = "occurrenceForm" runat = "server">
<div class ="dataRow">
<div class ="dataRowText">Last Name</div>
<div class ="dataRowEntrance">
<asp:TextBox ID = "lastNameTB" runat = "server"></asp:TextBox>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Last Name</div>
<div class ="dataRowEntrance">
<asp:TextBox ID = "firstNameTB" runat = "server"></asp:TextBox>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">MRN</div>
<div class ="dataRowEntrance">
<asp:TextBox ID = "mrnTB" runat = "server"></asp:TextBox>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Date of Occurence</div>
<div class ="dataRowEntrance">
<asp:Calendar ID="DateOfOccurenceCal" runat="server"></asp:Calendar>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Intervention</div>
<div class ="dataRowEntrance">
<asp:DropDownList ID="InterventionDDL" runat="server">
<asp:ListItem Value ="1">Phaco</asp:ListItem>
<asp:ListItem Value ="2">Injection</asp:ListItem>
<asp:ListItem Value ="3">Retina Surgery</asp:ListItem>
<asp:ListItem Value ="4">Transplant</asp:ListItem>
<asp:ListItem Value ="5">Other</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Intervention Surgeon</div>
<div class ="dataRowEntrance">
<asp:DropDownList ID="InterventionSurgeonDDL" runat="server">
<asp:ListItem Value ="8">Tabin</asp:ListItem>
<asp:ListItem Value ="9">Crandal</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Labs sent</div>
<div class ="dataRowEntrance">
<asp:CheckBox ID="labsSentCB" runat="server" />
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Precipitating Cause</div>
<div class ="dataRowEntrance">
<asp:DropDownList ID="preCauseDDL" runat="server">
<asp:ListItem Value ="1">Phaco</asp:ListItem>
<asp:ListItem Value ="2">Injection</asp:ListItem>
<asp:ListItem Value ="3">Retina Surgery</asp:ListItem>
<asp:ListItem Value ="4">Transplant</asp:ListItem>
<asp:ListItem Value ="5">Other</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Precipitating Surgeon</div>
<div class ="dataRowEntrance">
<asp:DropDownList ID="preSurgeonDDL" runat="server">
<asp:ListItem Value ="8">Tabin</asp:ListItem>
<asp:ListItem Value ="9">Crandal</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Data of Precipitating Cause</div>
<div class ="dataRowEntrance">
<asp:Calendar ID ="datePrecipitatingCal" runat="server"></asp:Calendar>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Hospital</div>
<div class ="dataRowEntrance">
<asp:DropDownList ID ="hospitalDDL" runat="server">
</asp:DropDownList>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">Additional Information</div>
<div class ="dataRowEntrance">
<asp:TextBox ID ="moreInfoTB" runat="server" Rows ="100"></asp:TextBox>
</div>
</div>
<div class ="dataRow">
<div class ="dataRowText">
<asp:Button ID ="submitEndoDataBtn" runat="server" Text="Submit" OnClick ="submitEndoDataBtn_Click"/>
</div>
</div>
</form>
</div>
</div>
</asp:Content>
答案 0 :(得分：5)
您的for循环条件错误，需要相反
for (int i=0; i < dbContext.Hospital_Datas.Count(); i++)
答案 1 :(得分：3)
using创建包装在for语句中，或者如果它位于类级别，则将其置于包含的类中。你的方法是在方法范围内，你的代码在没有处理它的情况下抛弃它（不好的做法！）for语句错误，但您确实不需要foreach，您可以使用Lambda，这将更容易阅读或使用Ashkan建议的数据绑定。 protected void addListItemsToPage() {
// wrap this in a using statement so the connection is closed and disposed
using(EndophthalmitisDBDataContext dbContext = new EndophthalmitisDBDataContext())
{
// replaced your wrong for statement with a foreach because you do not need a for statement (you are not using the indexer in a way that added any benifit)
foreach(var hospital in dbContext.Hospital_Datas)
ListItem li = new ListItem();
li.Text = hospital.Hospital_Name;
li.Value = hospital.HospitalID;
hospitalDDL.Items.Add(li);
}
// OR you could write it as a single statement
hospitalDDL.AddRange(dbContext.Hospital_Datas.Select(hospital => new ListItem(){Text = hospital.Hospital_Name, Value = hospital.HospitalID}));
}
}
语句。代码：
M-n-e答案 2 :(得分：1)
protected void addListItemsToPage() {
EndophthalmitisDBDataContext dbContext = new EndophthalmitisDBDataContext();
hospitalDDL.DataTextField = "Hospital_Name";
hospitalDDL.DataValueField = "HospitalID"
hospitalDDL.DataSource = dbContext.Hospital_Datas.ToList();
hospitalDDL.DataBind();
}