Convert file upload to multiple file upload c#

Question

Hello I'm trying to create a multiple file upload with C#, at the moment I can upload only one but I need to upload more than one, another thing is that I have to show a preview of the file (only images), I have code for a multiple file upload but only works in framework 4+ and my app is in 3.5, I'm thinking about using a foreach or something like that but I'm not sure so I hope you can help me, here is my C# method for file upload:

protected void UploadFile(object sender, EventArgs e)
    {
        if (FileUpload1.HasFile && this.alertatxt.Text != "" && this.pietxt.Text != "")
        {
            string extension = System.IO.Path.GetExtension(FileUpload1.FileName);

            if (extension == ".jpg" || extension == ".png" || extension == ".jpeg")
            {
                string filename = Path.GetFileName(FileUpload1.PostedFile.FileName);
                string contentType = FileUpload1.PostedFile.ContentType;
                int alerta = Convert.ToInt32(this.alertatxt.Text);
                string pie = this.pietxt.Text;
                using (Stream fs = FileUpload1.PostedFile.InputStream)
                {
                    using (BinaryReader br = new BinaryReader(fs))
                    {
                        byte[] bytes = br.ReadBytes((Int32)fs.Length);
                        string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
                        using (MySqlConnection con = new MySqlConnection(constr))
                        {
                            string query = "INSERT INTO foto(FileName, ContentType, Content, IdAlerta, PieFoto) VALUES (@FileName, @ContentType, @Content, @alerta, @pie)";
                            using (MySqlCommand cmd = new MySqlCommand(query))
                            {
                                cmd.Connection = con;
                                cmd.Parameters.AddWithValue("@FileName", filename);
                                cmd.Parameters.AddWithValue("@ContentType", contentType);
                                cmd.Parameters.AddWithValue("@Content", bytes);
                                cmd.Parameters.AddWithValue("@alerta", alerta);
                                cmd.Parameters.AddWithValue("@pie", pie);
                                con.Open();
                                cmd.ExecuteNonQuery();
                                con.Close();
                            }
                            ScriptManager.RegisterStartupScript(this, GetType(), "showalert", "alert('Uploaded.');", true);
                        }

                    }
                    this.pietxt.Text = "";
                }
            }
            ScriptManager.RegisterStartupScript(this, GetType(), "showalert", "alert('File must be .jpg . png .jpeg');", true);
            this.pietxt.Text = "";
        }
        else
        {
            ScriptManager.RegisterStartupScript(this, GetType(), "showalert", "alert('Fill all the fields.');", true);
            this.alertatxt.Focus();
            this.pietxt.Text = "";
        }

    }

EDIT: Image preview is not much important but however here is the code:

<div class="col-md-6 text-center form-group">
                                    <asp:FileUpload ID="FileUpload1" runat="server" onchange="showimagepreview(this)" />
                                </div>
    <div class="col-md-6 text-center form-group">
                                <img id="img" alt="" class="img-responsive" style="width: 300px" />
                            </div>

JS:

<script type="text/javascript">

    function showimagepreview(input) {

        if (input.files && input.files[0]) {
            var reader = new FileReader();
            reader.onload = function (e) {

                document.getElementsByTagName("img")[0].setAttribute("src", e.target.result);
            }
            reader.readAsDataURL(input.files[0]);
        }
    }

</script>

Sean Amos · Accepted Answer · 2016-08-26 14:37:49Z

1

Since the AllowMultiple property was only added to the FileUpload control in .Net 4.0, this means you are going to have to do some heavy lifting yourself.

If you have a small fixed maximum amount of uploads, for instance 3, you could simply add 3 FileUpload controls to the page and loop over Request.Files.

If you have large maximum limit, it might be better to add upload fields dynamically using javascript and loop over Request.Files property in the page code.

There are examples of doing exactly this:

http://www.c-sharpcorner.com/uploadfile/prathore/multiple-file-upload-using-jquery-in-asp-net-3-5/

http://www.aspsnippets.com/Articles/Uploading-Multiple-Files-using-FileUpload-Control-in-ASPNet-20-30-and-35.aspx

answered Aug 26, 2016 at 14:37

Sean Amos

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1 Comment

Francisco Fernandez Over a year ago

I'm going to check that information also I'm thinking about using a generic handler, thanks bro.

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