How to open pdf in iframe from binary data(in forms of bytes)?

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I am working on asp.net a web application. I retrieve a list of pdf in the grid view. now I want to show pdf in an iframe and I also retrieve pdf into bytes when clicking on grid view.

What I have tried:

C#

	cmd.Connection = con;
	con.Open();

	using (MySqlDataReader dr = cmd.ExecuteReader())
	{
		dr.Read();
		bytes = (byte[])dr["Data"];
		contentType = dr["ContentType"].ToString();
	}

	con.Close();
}

string base64 = Convert.ToBase64String(bytes, 0, bytes.Length);

string pdfframesrc = "data:Application/pdf;base64,{0}" + base64;

myiframe.Attributes["Src"] = pdfframesrc;

Posted 3-Mar-20 14:25pm

Member 14192879

Updated 4-Mar-20 4:44am

MadMyche

v2

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MadMyche 3-Mar-20 20:42pm

And what happens? Does it work? Throw an error? Do you get the content you want when debugging?

Member 14192879 3-Mar-20 22:18pm

no, it's not working, It does not show pdf in an iframe. as well as it is not showing any error

MadMyche 4-Mar-20 7:07am

What I would do would be to run this in the Debugger, set a Breakpoint, and then step through line by line to see what the values to see which line is causing the problem.

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Richard Deeming · Accepted Answer · 2020-03-04T04:44:00

Data URLs[^] have a maximum length which varies depending on the browser. For example, in Chrome, the limit is 2Mb. In Opera, the limit is 64Kb.

PDF files can easily exceed that limit.

Your best bet would be to create a generic handler to load the PDF file for a specific row, and point your <iframe> to that handler.

C#

myiframe.Attributes["src"] = ResolveUrl("~/loadPdfFile.ashx?id=" + idOfTheRecordToLoad);

LoadPdfFile.ashx:

C#

public class LoadPdfFileHandler : IHttpHandler
{
    public bool IsResuable => false;
    
    public void ProcessRequest(HttpContext context)
    {
        string id = context.Request.QueryString["id"];
        // TODO: Verify that the user is allowed to view the specified record.
        
        using (var connection = new MySqlConnection("..."))
        using (var command = new MySqlCommand("SELECT Data, ContentType FROM SomeTable WHERE ID = @ID", connection))
        {
            command.Parameters.AddWithValue("@ID", id);
            
            connection.Open();
            using (var reader = command.ExecuteReader(CommandBehavior.CloseConnection))
            {
                if (!reader.Read())
                {
                    context.Response.StatusCode = 404;
                    return;
                }

                string contentType = (string)dr["ContentType"];
                if (string.IsNullOrEmpty(contentType)) contentType = "application/octet-stream";
                context.Response.ContentType = contentType;
                
                byte[] bytes = (byte[])dr["Data"];
                context.Response.BinaryWrite(bytes);
            }
        }
    }
}