link to pdf file(asp.net)

Question

i have saved the pdf file to the database using file upload . now i want to retrive the pdf file from the database and it has to be linked to the linkbuttons that are dynamically created . so for each link button i have a pdf file linked to it. - how to do this in asp.net using C#

Answer 1

I would write a generic handler which will fetch the PDF from the database from a given id:

public class PdfHandler : IHttpHandler
{
    public void ProcessRequest(HttpContext context)
    {
        int id;
        if (int.TryParse(context.Request["id"], out id)) 
        {
            id = 0;
        }

        var connectionString = ConfigurationManager.ConnectionStrings["some_db"].ConnectionString;
        using (var connection = new SqlConnection(connectionString))
        using (var command = connection.CreateCommand())
        {
            connection.Open();
            command.CommandText = "select image from some_table where image_id = :id";
            command.Parameters.AddWithValue("id", id);
            using (var reader = command.ExecuteReader())
            {
                if (reader.Read()) 
                {
                    context.Response.ContentType = "application/pdf";
                    var cd = new ContentDisposition();
                    cd.FileName = "test.pdf";
                    cd.Inline = true;
                    context.Response.AddHeader("Content-Disposition", cd.ToString());

                    long bytesRead;
                    int size = 1024;
                    var buffer = new byte[size];
                    long dataIndex = 0;
                    while ((bytesRead = reader.GetBytes(0, dataIndex, buffer, 0, buffer.Length)) > 0)
                    {
                        var actual = new byte[bytesRead];
                        Buffer.BlockCopy(buffer, 0, actual, 0, (int)bytesRead);
                        context.Response.OutputStream.Write(actual, 0, actual.Length);
                        dataIndex += bytesRead;
                    }
                }
                else
                {
                    context.Response.ContentType = "text/plain";
                    context.Response.Write("Not found");
                    context.Response.StatusCode = 404;
                }
            }
        }
    }

    public bool IsReusable
    {
        get { return false; }
    }
}

And in the aspx page just put anchors that reference this handler:

<a href="/PdfHandler.ashx?id=1">pdf 1</a>
<a href="/PdfHandler.ashx?id=2">pdf 2</a>
<a href="/PdfHandler.ashx?id=3">pdf 3</a>
...

Answer 2

First you'd have to read the records from the database.

Let's say you have the following table structure:

Id, Name, BinaryPdfData

You use ADO.NET, Linq2SQL or whatever you're using to "SELECT" Id and Name into an IEnumerable (for example a List or DataSet).

Then you bind that to an ASP Repeater where the ItemTemplate contains a LinkButton and the code behind for the Click event would then redirect you to some download page for example "downloadpdf.aspx?id={0}"

Where {0} is the Id of the record.

The download.aspx page reads the specified record from the database and puts the binary pdf data in a buffer array.

Next you'll have to set the content type etc...

I don't have time to build a good example, but you'll probably need this:

Response.Clear()

//set the content type to PDF
Response.ContentType = "application/pdf"

//add content type header 
Response.AddHeader("Content-Type", "application/pdf")

//set the content disposition
Response.AddHeader("Content-Disposition", "inline;filename=helloworld.pdf")

//write the buffer with pdf file to the output
Response.BinaryWrite(Buffer)

Response.End()