动态GridView的下拉列表

Question

我有一个GridView与以下领域

讲座ID，讲师名，主题和GridView控件中包含的链接按钮可插入，编辑和DELETE.what我 需要的是，当我点击，编辑科目列应该包含DROPDOWN列表以选择主题。 如果GridView行不处于编辑模式或INSERT模式DROPDOWN不应显示，并只显示讲师讲授的主题。

Answer 1

这可以通过主题列一个TemplateField来完成，如下图所示：

<asp:TemplateField Header="Subject"> 
        <EditItemTemplate> 
         <asp:DropDownList ID="subjectDDl" runat="server"></asp:DropDownList> 
        </EditItemTemplate> 
        <ItemTemplate> 
         <asp:Label ID="subjectLabel" runat="server"></asp:Label> 
        </ItemTemplate> 
       </asp:TemplateField> 

您可能已经加入ButtonField字段列调用编辑，插入和删除功能。

Answer 2

做这种数据绑定的诀窍是使用两个数据源，一个包含讲座ID，讲师姓名和主题ID，另一个包含主题列表。你可以与任何DataSource控件的做到这一点 - 这是一个使用的SqlDataSource演示：

<!-- First data source is the main data source for the gridview --> 
<asp:SqlDataSource runat="server" id="LectureDataSource" 
SelectCommand="SELECT l.LectureId, l.Lecturer, l.SubjectId, s.Subject FROM Lecture l INNER JOIN Subject s ON l.SubjectId = s.SubjectID" 
UpdateCommand="UPDATE Lecture SET Lecturer = @Lecturer, SubjectId = @SubjectId" 
DeleteCommand="DELETE FROM Lecture WHERE LectureId = @LectureId" InsertCommand="INSERT INTO Lecture (Lecturer, SubjectId) VALUES (@Lecturer, @SubjectID)" 
> 
<DeleteParameters> 
    <asp:ControlParameter ControlID="LectureGridView" Name="LectureId" 
     PropertyName="SelectedValue" /> 
</DeleteParameters> 
<UpdateParameters> 
    <asp:Parameter Name="Lecturer" /> 
    <asp:Parameter Name="SubjectId" /> 
</UpdateParameters> 
</asp:SqlDataSource> 

<!-- Second data source is the data source for the Subject dropdownlist --> 
<asp:SqlDataSource runat="server" ID="SubjectDataSource" 
SelectCommand="SELECT SubjectId, Subject FROM Subject ORDER BY SubjectId" /> 

<asp:GridView runat="server" AutoGenerateColumns="False" DataSourceID="LectureDataSource" 
    ID="LectureGridView" DataKeyNames="LectureId" > 
    <!-- Setting the DataKeyNames property allows us to delete by using the SelectedValue --> 
    <Columns> 
     <asp:TemplateField> 
      <ItemTemplate> 
       <asp:LinkButton Text="Edit" runat="server" CommandName="Edit" />&nbsp; 
       <asp:LinkButton Text="Delete" runat="server" CommandName="Delete" /> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:LinkButton Text="Update" runat="server" CommandName="Update" /> 
       <asp:LinkButton Text="Cancel" runat="server" CommandName="Cancel" /> 
      </EditItemTemplate> 
      <ItemStyle HorizontalAlign="Center" /> 
     </asp:TemplateField> 
     <asp:BoundField DataField="LectureId" HeaderText="Lecture Id" ReadOnly="true" /> 
     <asp:TemplateField HeaderText="Lecturer"> 
      <ItemTemplate> 
       <asp:Label Text='<%# Bind("Lecturer") %>' runat="server" ID="LecturerLabel" /> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:TextBox ID="LecturerEditTextBox" runat="server" Text='<%# Bind("Lecturer") %>'></asp:TextBox> 
      </EditItemTemplate> 
     </asp:TemplateField> 
     <asp:TemplateField> 
      <ItemTemplate> 
       <!-- The label is bound to the subject text field from the LectureDataSource --> 
       <asp:Label ID="SubjectLabel" runat="server" Text='<%# Bind("Subject") %>' /> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <!-- In Edit mode the dropdownlist is bound to the SubjectDataSource, but we also set the text value from the LectureDataSource --> 
       <asp:DropDownList ID="SubjectEditDropDownList" runat="server" DataSourceID="SubjectDataSource" 
        DataTextField="Subject" DataValueField="SubjectId" Text='<%# Bind("SubjectId") %>'> 
       </asp:DropDownList> 
      </EditItemTemplate> 
     </asp:TemplateField> 
    </Columns> 
</asp:GridView>