How Can I Fix Issues While Converting a .txt File to a .pdf in Django?

Recently, I encountered a common issue when trying to convert a .txt file to a .pdf file within a Django application. Despite the fact that the PDF file was created, its content was not visible when attempting to view it. Let’s delve into what might be causing this issue and explore how we can resolve it.

Original Code Review

The intention of my original script was straightforward: to take an uploaded text file via a POST request, read its contents, and then write that content into a PDF file. Here’s the original code snippet:

def txttopdf(request):
    if request.method == 'POST':
        txt = request.FILES['txt']
        pdf = fpdf.FPDF()
        pdf.add_page()
        pdf.set_font("Arial", size=12)
        pdf.cell(200, 10, txt.read().decode('utf-8'), 0, 1)
        return HttpResponse(pdf.output(dest='S'), content_type='application/pdf')
    return render(request, 'txttopdf.html')

Upon reviewing this script, everything seems in order at first glance: the file is fetched from the request, the PDF is initialized, a page and a font are added, and the file’s content is intended to be placed into the PDF. However, crucial elements were overlooked, leading to issues with the visibility of the PDF’s content.

Identifying the Issue

1. Encoding and Decoding: The line where the .txt file’s content is read might be mishandled in terms of encoding. If there’s an encoding issue, it could prevent text from appearing correctly.

1. Cell Function Usage in FPDF: The pdf.cell() function is sensitive to what it can properly display. If there are newline characters in the text file, simply using pdf.cell() might not handle these correctly, and the text will not wrap as expected.

The Revised Solution

To address both potential issues – handling encoding properly and managing multiple lines – we can modify the script as follows:

def txttopdf(request):
    if request.method == 'POST':
        # Fetch the text file from the uploaded files
        txt_file = request.FILES.get('txt')
        
        if txt_file:
            # Initialize PDF
            pdf = fpdf.FPDF(format='letter')  # Set as letter format or size could be A4 as well
            pdf.add_page()
            pdf.set_font("Arial", size=12)
            
            # Read and decode the content of text file
            content = txt_file.read().decode('utf-8')

            # Handling multiple lines
            lines = content.split('\n')
            for line in lines:
                pdf.cell(200, 10, line, ln=True)  # Ensure 'ln' is set to True to manage new lines

            # Return response
            response = HttpResponse(pdf.output(dest='S'), content_type='application/pdf')
            response['Content-Disposition'] = 'attachment; filename="text_to_pdf.pdf"'
            return response
    # Render the form if not POST method
    return render(request, 'txttopdf.html')

Explanation

• Error Handling: We now check if the file is correctly fetched with txt_file = request.FILES.get('txt'). This adds a layer of error handling.

• Handling New Lines: We split the content by new lines and loop through each line. This ensures that every new line in the original text file starts on a new line in the PDF.

• Content-Disposition Header: Additionally, I’ve added a ‘Content-Disposition’ header to the response. This prompts the browser to open a download dialog or save the PDF file, which could be helpful for end-users to directly download the converted PDF.

By modifying the code in these ways, we can ensure that the generated PDF will correctly display the content of the .txt file, regardless of its length or formatting. This method also improves the robustness and user-friendliness of the function.