遍歷對象中的屬性並填充它
[英]loop through properties in object and populate it
問題描述
我試圖遍歷對象中的屬性並將其應用為字符串。
例如，要動態執行此操作將是：
Dim objAnswers As New DAL.Quiz.QuizAnswers
With objAnswers
.Question1 = "text1"
.Question2 = "text2"
.Question3 = "text3"
.Question4 = "text4"
.Question5 = "text5"
End With
但是我試圖遍歷對象的屬性，然后像這樣應用它：
Dim objAnswers As New DAL.Quiz.QuizAnswers
For Each rptItem As RepeaterItem In repeater1.Items
Dim ddlAnswers As App_Controls_Forms_DropDownList = CType(rptItem.FindControl("DropDownList1"), App_Controls_Forms_DropDownList)
For Each p As System.Reflection.PropertyInfo In objAnswers.GetType().GetProperties()
If p.ToString.StartsWith("question") Then
p = ddlAnswers.SelectedText
End If
Next
Next
我正在嘗試使用中繼器中的下拉列表中的s填充對象的字符串。 這是我想用偽做的事情-對於轉發器中的每一行，從下拉列表中獲取文本並填充以“問題”開頭的對象屬性
謝謝您的幫助！
編輯：
Dim objAnswers As New DAL.Quiz.QuizAnswers
For Each p As System.Reflection.PropertyInfo In objAnswers.GetType().GetProperties()
For Each rptItem As RepeaterItem In repeater1.Items
Dim ddlAnswers As App_Controls_Forms_DropDownList = CType(rptItem.FindControl("DropDownList1"), App_Controls_Forms_DropDownList)
If p.ToString.StartsWith("Question") Then
p.SetValue(objAnswers, ddlAnswers.SelectedText)
End If
Next
Next
3 個解決方案
解決方案1
1 已采納 2018-12-10 13:54:50
我不使用vb，因此某些名稱可能是錯誤的。 我將循環這些項目，找到單個匹配的屬性並將其設置如下：
Dim objAnswers As New DAL.Quiz.QuizAnswers
Dim i as Integer
For i = 0 To repeater1.Items.Length - 1
Dim ddlAnswers As App_Controls_Forms_DropDownList = CType(repeater1.Items[i].FindControl("DropDownList1"), App_Controls_Forms_DropDownList)
Dim p as System.Reflection.PropertyInfo = objAnswers.GetType().GetProperty("Question" & i + 1)
p.SetValue(objAnswers, ddlAnswers.SelectedText)
Next
解決方案2
0 2018-12-11 02:11:33
這是您兩個問題的（過度）簡化解決方案。
--DB structure
create table dbo.questions(
id int identity(1,1) primary key,
question nvarchar(100) not null,
correctAnswerId int null --single correct answer
)
go
create table dbo.answers(
id int identity(1,1) primary key,
questionId int not null,
answer nvarchar(100) not null,
--isCorrect bit default 0 -- multiple correct answers
foreign key(questionId) references dbo.questions(id)
)
go
alter table dbo.questions
add constraint fk_questions_answers foreign key (correctAnswerId) references dbo.answers(id)
//.aspx page
<!DOCTYPE html>
<%@ Page Language="C#" %>
<script runat="server">
protected void btnSubmit_Click(object sender, EventArgs e)
{
int questions = 0;
int correct = 0;
//int questionId // if you want to save it
//int answerId // if you want to save it
foreach(RepeaterItem item in rpQuestions.Items)
{
if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem)
{
questions++;
string correctAnswerId = ((Literal)item.FindControl("correctAnswerId")).Text;
var answerList = item.FindControl("lstAnswers") as RadioButtonList;
if (answerList.SelectedValue == correctAnswerId)
correct++;
}
}
result.Text = string.Format("{0} correct answers out of {1}", correct, questions);
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>quiz ver 0.0</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Repeater ID="rpQuestions" runat="server" DataSourceID="sqlQuestions">
<ItemTemplate>
<asp:Literal ID="questionId" runat="server" Text='<%#Eval("id") %>' Visible="false"></asp:Literal>
<asp:Literal ID="correctAnswerId" runat="server" Text='<%#Eval("correctAnswerId") %>' Visible="false"></asp:Literal>
<h2><asp:Literal runat="server" Text='<%#Eval("question") %>'></asp:Literal></h2>
<%-- radio buttons are easier to use than dropdown --%>
<asp:RadioButtonList ID="lstAnswers" runat="server" DataTextField="answer" DataValueField="id" DataSourceID="sqlAnswers"></asp:RadioButtonList>
<%-- Bind possible answers declarativelly --%>
<%-- This DataSource must be inside ItemTemplate --%>
<asp:SqlDataSource ID="sqlAnswers" runat="server" ConnectionString="<%$ ConnectionStrings:DBConnection %>"
SelectCommand="SELECT id, answer FROM dbo.answers where questionId=@questionId">
<SelectParameters>
<asp:ControlParameter Name="questionId" ControlID="questionId" PropertyName="Text" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
</ItemTemplate>
</asp:Repeater>
<asp:SqlDataSource ID="sqlQuestions" runat="server" ConnectionString="<%$ ConnectionStrings:DBConnection %>"
SelectCommand="SELECT id, question, correctAnswerId FROM questions"></asp:SqlDataSource>
<asp:Button ID="btnSubmit" runat="server" Text="Submit answers" OnClick="btnSubmit_Click" />
<div>
<asp:Literal ID="result" runat="server"></asp:Literal>
</div>
</div>
</form>
</body>
</html>
解決方案3
0 2018-12-15 15:15:19
您已經知道要設置的屬性，不需要反射：
Dim objAnswers As New DAL.Quiz.QuizAnswers
Dim answers = New Dictionary(Of String, String)
Dim i as Integer
For i = 0 To repeater1.Items.Length - 1
Dim ddlAnswers = CType(repeater1.Items(i).
FindControl("DropDownList1"), App_Controls_Forms_DropDownList)
answers.Add("Question" & i + 1, ddlAnswers.SelectedText)
Next
objAnswers.Question1=answers(NameOf(objAnswers.Question1))
objAnswers.Question2=answers(NameOf(objAnswers.Question2))
objAnswers.Question3=answers(NameOf(objAnswers.Question3))
objAnswers.Question4=answers(NameOf(objAnswers.Question4))
objAnswers.Question5=answers(NameOf(objAnswers.Question5))
更好的是擁有一個接受字典的構造函數，並從那里設置屬性。
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