使用 ASP.NET 将 Bitmap 图像从数据库显示到 GridView

Question

I am currently trying to display the a QR code bitmap image that is being stored as varbinary in the SQL database into a gridview, and I have referred to this link: [https://www.aspsnippets.com/Articles/Display-images-from-SQL-Server-Database-in-ASP.Net-GridView-control.aspx]

However, I am unable to display the image properly in the gridview table and I couldn't seem to figure out the error with it.

This is my code for the gridview code behind:

      if (!this.IsPostBack)
            {
                using (SqlDataAdapter sda = new SqlDataAdapter("SELECT * FROM PARCEL", conn))
                {
                    DataTable dt = new DataTable();
                    sda.Fill(dt);
                    GridView1.DataSource = dt;
                    GridView1.DataBind(); 
                }
            }
        }

        protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                DataRowView dr = (DataRowView)e.Row.DataItem;
                string imageUrl = "data:image/png;base64," + Convert.ToBase64String((byte[])dr["QRCode"]);
                (e.Row.FindControl("QRCode") as Image).ImageUrl = imageUrl;
            }
        }

The markup for gridview:

<asp:GridView 
        ID="GridView1" 
        runat="server" 
        AutoGenerateColumns="False" 
        DataKeyNames="ConsignmentNumber" 
        AllowPaging="True" 
        HorizontalAlign="Center" 
        ViewStateMode="Enabled">

        <Columns>
            <asp:BoundField DataField="ConsignmentNumber" HeaderText="ConsignmentNumber" ReadOnly="True" SortExpression="ConsignmentNumber" /> 
            <asp:BoundField DataField="Status" HeaderText="Status" SortExpression="Status" />
            <asp:TemplateField>
                <ItemTemplate>
                    <asp:Image ID="QRCode" runat="server" HeaderText="QRCode" />
                </ItemTemplate>
            </asp:TemplateField>
           
        </Columns>
    </asp:GridView>

I would like to know if there is any solution or suggestion that I can apply in order to display the images properly.

Answer 1

Judging by the error you are experiencing, you have defined a DataSourceId in your markup AND are setting the datasource in codebehind. You can do either, but not both. That is what the error is telling you.

<asp:GridView ID="GridView1" runat="server" 
    DataSourceID="yourdatasource">
    <Columns>
       <!-- ... -->
    </Columns>
</asp:GridView>

Find the DataSourceID in your markup and remove it, as you are setting it in your code-behind cs file:

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