How can I open a PDF then ZIP it and then create a Base64 encoded string in C#

Question

I have a task to embed a Zipped PDF retrieved from the file system into an XML document in C#. The specification states:

For instance, retrieve the file ‘INV001.pdf’

Compress it to get a ‘INV001.zip’ file.

2/ Encode each .zip to Base64 format

The goal is to transform the zip file, which is a binary object, into a text file.

The content of the text file will be a text String which we will be able to copy/paste into the .xml file

This is where I've got to with the code

string docText = null;
using (FileStream originalFileStream = File.Open(myFilePath, FileMode.Open))
{
    using (FileStream compressedFileStream = File.Create("compressed.gz"))
    {
        using (var compressor = new GZipStream(compressedFileStream, CompressionMode.Compress, true))
        {
            originalFileStream.CopyTo(compressor);
            using (StreamReader sr = new StreamReader(compressor))
            {
                docText = sr.ReadToEnd();
            }
        }
    }
}

The code throws an exception on the line

using (StreamReader sr = new StreamReader(compressor))

"Stream was not readable". Am I on the right track here? There is no requirement to store the ZIP, only to paste it as Base64 text into an XML file. I've found some articles on SO that hint at some approaches but none seem to work! Many thanks

Because it's the format required by a foreign government department, and even though I work for quite a big company I don't think there's any point in trying to fight that battle. So can anyone answer the actual question, regardless of whether you think it's a skunked notion? — Edwardo, Jan 08 '22 at 23:27
My problem is that I'm having trouble creating the zip in memory. — Edwardo, Jan 10 '22 at 08:21

score 1 · Accepted Answer · answered Jan 10 '22 at 10:45

This seems to work:

string docText = null;
byte[] data;
using (FileStream originalFileStream = File.Open(myFilePath, FileMode.Open))
{
    using (FileStream compressedFileStream = File.Create("compressed.gz"))
    {
        using (var compressor = new GZipStream(compressedFileStream, CompressionMode.Compress, true))
        {
            originalFileStream.CopyTo(compressor);
            using (MemoryStream ms = new MemoryStream())
            {
                compressor.BaseStream.Seek(0, SeekOrigin.Begin);
                compressor.BaseStream.Position = 0;
                compressor.BaseStream.CopyTo(ms);
                data = ms.ToArray();
                docText = Convert.ToBase64String(data);
            }
        }
    }
}

How can I open a PDF then ZIP it and then create a Base64 encoded string in C#

1 Answers1