图像未在数据库中的gridview中绑定

Question

以下是我的代码...我正在尝试将图像存储在数据库中。我使用varbinary（MAX）数据类型在数据库中存储数据字节。请告诉我哪里出错了。

    int qtype = Convert.ToInt32(ddl_q_Type.SelectedValue);
                var getQ = (from q in obj.QuestionRegistrations
                            orderby q.QueCode ascending
                            where q.QueQuesType == qtype && q.QueLanguageCode == 1
                            select new { q.QueCode, q.QueQuestion }
                                ).ToArray();


                index = Convert.ToInt32(ViewState["index"].ToString()) + 1;
                ViewState["index"] = index;
                previosIndex = index - 1;
                ViewState["previosIndex"] = previosIndex;
                txt_question.Text = getQ[index].QueQuestion;
                lblqcode.Text = getQ[index].QueCode.ToString();


                int qcode = Convert.ToInt32(lblqcode.Text);
                var options = (from opt in obj.QuestionAndOptionsMappings
                               where opt.QueMapQuestionCode == qcode
                               select new { opt.QueMapOptions, opt.QueMapCorrectAnswer, opt.QueMapId, opt.QueMapImage }
                                   ).ToList();


                DataTable dt = new DataTable();

                dt.Columns.Add("QueMapOptions", typeof(string));
                dt.Columns.Add("QueMapId", typeof(string));
                dt.Columns.Add("QueMapImage", typeof(string));

                foreach (var y in options)
                {
                    DataRow dr = dt.NewRow();
                    dr["QueMapOptions"] = y.QueMapOptions;
                    dr["QueMapId"] = y.QueMapId;
                    dr["QueMapImage"] = (Byte[])y.QueMapImage;

                    dt.Rows.Add(dr);
                }

 GridView1.DataSource = dt;
            GridView1.DataBind();

此代码用于存储数据库中的图像

for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                FileUpload fp = (FileUpload)GridView1.Rows[i].Cells[2].FindControl("fp");
                Label lblmapid = (Label)GridView1.Rows[i].Cells[1].FindControl("lblmapid");
                bool e1 = fp.HasFile;
                int mapiidd = Convert.ToInt32(lblmapid.Text);
                if (fp.HasFile)
                {
                    string path = Server.MapPath("~/Uploads/") + fp.FileName;
                    fp.SaveAs(path);
                    byte[] imageBytes =
                        File.ReadAllBytes(System.Web.HttpContext.Current.Server.MapPath("~/Uploads/") + fp.FileName);
                    int qcodelbl = Convert.ToInt32(lblqcode.Text);
                    QuestionAndOptionsMapping qmap = new QuestionAndOptionsMapping();

                    var update = obj.QuestionAndOptionsMappings.Where(q => q.QueMapId == mapiidd && q.QueMapQuestionCode == qcodelbl)
                        ;
                    update.SingleOrDefault().QueMapImage = imageBytes;
                    obj.SaveChanges();
                }

            }

ASPX代码

<asp:GridView ID="GridView1" runat="server" Width="100%" AutoGenerateColumns="false">
                        <Columns>
                            <asp:TemplateField HeaderText="OPTIONS" HeaderStyle-Width="55%">
                                <ItemTemplate>
                                    <asp:TextBox ID="Option" runat="server" Text='<%#Eval("QueMapOptions") %>' Height="40px"
                                        Width="500px"></asp:TextBox>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Sub Section" HeaderStyle-Width="15%" Visible="false">
                                <ItemTemplate>
                                    <asp:Label ID="lblmapid" runat="server" Text='<%#Eval("QueMapId") %>'></asp:Label>
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Sub Section" HeaderStyle-Width="15%">
                                <ItemTemplate>
                                    <asp:CheckBox ID="Chk_correct_Ans" runat="server" />
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Sub Section" HeaderStyle-Width="15%">
                                <ItemTemplate>
                                    <asp:FileUpload ID="fp" runat="server" />
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField HeaderText="Sub Section" HeaderStyle-Width="15%">
                                <ItemTemplate>
                                    <asp:Image ID="Image1" runat="server" ImageUrl='<%#Eval("QueMapImage") %>' Height="80px"
                                        Width="100px" />
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                    </asp:GridView>

Answer 1

好的，您不能将二进制列绑定到GridView列。你需要使用Response.BinaryWrite方法。

以下几个步骤可以实现您的目标

1. 创建一个通用处理程序来读取二进制数据。我们称之为 ImageHandler.ashx 。确保将表的主键传递给此处理程序。编写下面的处理程序代码（仅作为示例）。

   public void ProcessRequest (HttpContext context) 
       {
   

   string connectionString = ConfigurationManager.ConnectionStrings [＆＃34; DBConnection＆＃34;]。ConnectionString;

           SqlConnection conn = new SqlConnection(connectionString);
   
           SqlCommand cmd = new SqlCommand();
   
           cmd.CommandText = "Select [Content] from Images where ID =@ID";
   
           cmd.CommandType = CommandType.Text;
   
           cmd.Connection = conn;
   
           SqlParameter ImageID = new SqlParameter("@ID", SqlDbType.BigInt);
           ImageID.Value = context.Request.QueryString["ID"];
           cmd.Parameters.Add(ImageID);
           conn.Open();
           SqlDataReader dReader = cmd.ExecuteReader();
           dReader.Read();
           context.Response.BinaryWrite((byte[])dReader["Content"]);
           dReader.Close();
           conn.Close();
       }
   

2. 并像这样调用处理程序。

   ImageUrl =＆＃39;＆lt;％＃＆＃34; ImageHandler.ashx？ID =＆＃34; + Eval（＆＃34; ID＆＃34;）％＆gt;＆＃39;

而不是

ImageUrl='<%#Eval("QueMapImage") %>'

Here's我从上面的例子中提取的一个完整示例。

一切顺利！