how can i convert any kind of text file into a PDF file in asp.net web api using c# in entity frame work?

Question

i want to upload the text files to the server by converting them into base64 string from android side and send them to the server using asp.net web api i again decode them in asp.net web api ..but before actually storing them into my directory i want to convert the files into a pdf document whether they were .docx .txt or of any other type

i have already tried the following code but it gives the error object reference not set to an instance of an object i don't know how to solve it and what are the issues

private static string saveFile(long id, string base64String) { try {

            String path = HttpContext.Current.Server.MapPath("~/images"); //Path

            //Check if directory exist
            if (!System.IO.Directory.Exists(path))
            {
                System.IO.Directory.CreateDirectory(path); //Create directory if it doesn't exist
            }

            string imageName = "Documentation" + id + ".docx";

            //set the image path
            string imgPath = Path.Combine(path, imageName);
            byte[] imageBytes = Convert.FromBase64String(base64String);

            File.WriteAllBytes(imgPath, imageBytes);

            Word2Pdf objWordPDF = new Word2Pdf();
            object FromLocation = path+"\\"+imageName;
            string FileExtension = Path.GetExtension(imageName);
            string ChangeExtension = imageName.Replace(FileExtension, ".pdf");

            if (FileExtension == ".doc" || FileExtension == ".docx")
            {
                object ToLocation = path + "\\" + ChangeExtension;
                objWordPDF.InputLocation = FromLocation;
                objWordPDF.OutputLocation = ToLocation;
                objWordPDF.Word2PdfCOnversion();
            }


            return imageName;
        }
        catch (Exception ex)
        {
            return null;
        }

    }

this code is not producing the desired result it returns a null as image name

Answer 1

I don't actually have a solid answer but in my experience i once did this using wkhtmltopdf tool wich is an outside tool to convert webpages to pdf. the logic goes as the need to render whatever u want as pdf into an view and use the service of wkhtmltopdf to convert it.

for the service here is the sample i have :

ServicePDF.cs :

public class ServicePdf : IServicePdf
{
    private readonly IConfiguration _configuration;
    public ServicePdf(IConfiguration configuration)
    {
        _configuration = configuration;
    }
    public PdfGlobalOptions Options { set; get; }
    /// <summary>
    /// Pertmet la génération d'un fichier PDF
    /// </summary>
    /// <param name="url">l'url à convertir exp : http://www.google.fr</param>
    /// <param name = "filename" > Nom du fichier pdf en output</param>
    /// <returns>byte[] pdf en cas de succès, le message d'erreur en cas d'echec</returns>
    public object GeneratePDF(string url, string filename)
    {

        Process process = new Process();
        ProcessStartInfo startInfo = new ProcessStartInfo();
        startInfo.WindowStyle = ProcessWindowStyle.Hidden;
        startInfo.FileName = _configuration.GetSection("wkhtmltopdf").GetSection("Path").Value + _configuration.GetSection("wkhtmltopdf").GetSection("Program").Value;
        StringBuilder arguments = new StringBuilder();

        arguments.Append("--page-size ");
        arguments.Append("A4");
        arguments.Append(" ");

        if (Options.Orientation != PdfOrientation.Portrait)
        {
            arguments.Append("--orientation Landscape");
            arguments.Append(" ");
        }
        if (Options.MarginLeft.HasValue)
        {
            arguments.Append("--margin-left ");
            arguments.Append(Options.MarginLeft);
            arguments.Append(" ");
        }
        if (Options.MarginTop.HasValue)
        {
            arguments.Append("--margin-top ");
            arguments.Append(Options.MarginTop);
            arguments.Append(" ");
        }
        if (Options.MarginRight.HasValue)
        {
            arguments.Append("--margin-right ");
            arguments.Append(Options.MarginRight);
            arguments.Append(" ");
        }
        if (Options.MarginBottom.HasValue)
        {
            arguments.Append("--margin-bottom ");
            arguments.Append(Options.MarginBottom);
            arguments.Append(" ");
        }
        if (Options.PageWidth.HasValue)
        {
            arguments.Append("--page-width ");
            arguments.Append(Options.PageWidth);
            arguments.Append(" ");

        }

        if (Options.PageHeight.HasValue)
        {
            arguments.Append("--page-height ");
            arguments.Append(Options.PageHeight);
            arguments.Append(" ");

        }
        if (Options.HeaderSpacing.HasValue)
        {
            arguments.Append("--header-spacing ");
            arguments.Append(Options.HeaderSpacing);
            arguments.Append(" ");

        }

        if (Options.FooterSpacing.HasValue)
        {
            arguments.Append("--footer-spacing ");
            arguments.Append(Options.FooterSpacing);
            arguments.Append(" ");

        }
        if (!string.IsNullOrEmpty(Options.Header))
        {
            arguments.Append("--header-html ");
            arguments.Append(Options.Header);
            arguments.Append(" ");

        }
        if (!string.IsNullOrEmpty(Options.Footer))
        {
            arguments.Append("--footer-html ");
            arguments.Append(Options.Footer);
            arguments.Append(" ");

        }

        arguments.Append(url);
        arguments.Append(" ");
        arguments.Append(System.IO.Path.GetTempPath());
        arguments.Append(filename);



        startInfo.Arguments = arguments.ToString();
        startInfo.RedirectStandardOutput = true;
        startInfo.RedirectStandardError = true;


        process.StartInfo = startInfo;
        process.Start();



        var errors = process.StandardError.ReadToEnd();

        if (System.IO.File.Exists(System.IO.Path.GetTempPath() + filename))
        {
            byte[] pdf = System.IO.File.ReadAllBytes(System.IO.Path.GetTempPath() + filename);
            return pdf;
        }
        return errors;
    }
}

IServicePDF.cs

public interface IServicePdf
{
    object GeneratePDF(string url, string filename);
    PdfGlobalOptions Options { set; get; }
}

PdfGlovalOptions.cs

public enum PdfOrientation { Landscape, Portrait };
public class PdfGlobalOptions
{
    public float? MarginTop { get; set; }
    public float? MarginLeft { get; set; }
    public float? MarginBottom { get; set; }
    public float? MarginRight { get; set; }

    public float? PageWidth { get; set; } 
    public float? PageHeight { get; set; }
    public string Header { get; set; }
    public string Footer { get; set; }
    public float? HeaderSpacing { get; set; }
    public PdfOrientation Orientation { get; set; }

    public float? FooterSpacing { get; set; }
}

and lastly in your app config add the configuration necessary :

"wkhtmltopdf": {
"Path": "C:\\Program Files\\wkhtmltopdf\\bin\\",
"Program": "wkhtmltopdf.exe" }