5 Best Ways to Convert Python Bytes to PDF

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💡 Problem Formulation: Developers often need to convert data from Python byte literals to PDF files. This article addresses the problem of taking a bytes object in Python, which may represent a PDF file’s binary content, and saving this to a readable PDF file on disk. For example, if you’ve got pdf_content = b'%PDF-1.4...' as your input, you are looking to save this as ‘output.pdf’ on your local filesystem.

Method 1: Using PyPDF2 Library

PyPDF2 is a pure-Python library built as a PDF toolkit. It is capable of extracting document information, splitting documents, merging documents, and more. In our case, it’s quite efficient for saving byte strings as PDF files. To use this method, PyPDF2 must be installed and imported in your Python script.

Here’s an example:

from PyPDF2 import PdfFileReader, PdfFileWriter
import io

# Simulating a bytes object of a PDF file.
pdf_bytes = b'%PDF-1.4...'

# Wrapping the bytes object with BytesIO class to create a file-like object.
pdf_buffer = io.BytesIO(pdf_bytes)

# Creating a PdfFileReader object for reading from the file-like object.
pdf_reader = PdfFileReader(pdf_buffer)

# Creating a PdfFileWriter object for writing to a new PDF.
pdf_writer = PdfFileWriter()

# Copying content from the reader to the writer.
for page_num in range(pdf_reader.numPages):
    page = pdf_reader.getPage(page_num)
    pdf_writer.addPage(page)

# Saving the new PDF to a file.
with open('output.pdf', 'wb') as output_pdf:
    pdf_writer.write(output_pdf)

The output will be a file named output.pdf written to your local directory, containing the data from pdf_bytes.

This code snippet takes a bytes object that represents PDF content and writes it to a ‘output.pdf’ file. It does so by reading the bytes through a file-like buffer using io.BytesIO and processes it with PyPDF2 tools.

Method 2: Using built-in open function

If the bytes object already represents a complete PDF file, you can write it directly to a file using Python’s built-in open function without any additional PDF processing libraries. This is straightforward and does not depend on any third-party packages.

Here’s an example:

pdf_bytes = b'%PDF-1.4...'

# Writing bytes directly to PDF file.
with open('output.pdf', 'wb') as pdf_file:
    pdf_file.write(pdf_bytes)

The resulting ‘output.pdf’ file will contain the original PDF data unchanged.

This succinct code example shows how to convert a bytes object into a PDF file by simply opening a file in write-binary mode and writing the bytes to it, resulting in an output PDF.

Method 3: Using ReportLab Library

ReportLab is another powerful library for creating PDFs from scratch. Instead of assuming PDF content is already fully created, it is best used when you need to generate PDFs dynamically.

Here’s an example:

from reportlab.pdfgen import canvas
import io

# Suppose pdf_bytes contains some drawing or text information.
pdf_bytes = b'This is some text that will go into a PDF.'

# Using bytes data to create a PDF with ReportLab
pdf_buffer = io.BytesIO()

# Instantiate a canvas object
c = canvas.Canvas(pdf_buffer)
# Add content using canvas methods
c.drawString(100, 750, pdf_bytes.decode('utf-8'))  # Decoding bytes to string for drawing
c.showPage()
c.save()

# Reset buffer position to the beginning
pdf_buffer.seek(0)

# Write the PDF content to a file
with open('output.pdf', 'wb') as f:
    f.write(pdf_buffer.getvalue())

A new PDF file called ‘output.pdf’ is created and contains ‘This is some text that will go into a PDF’ as content drawn in the document.

This code uses ReportLab to write text contained within a bytes object to a PDF. The BytesIO object works as in-memory file, which then is written into an actual file.

Method 4: FPDF Library

The FPDF library is a flexible and easy-to-use Python library to create PDFs programmatically. With its simplistic API, you can create PDFs and include pre-existing content from bytes.

Here’s an example:

from fpdf import FPDF

# Assume pdf_bytes carries byte content for PDF
pdf_bytes = b'%PDF-1.4...'

class PDF(FPDF):
    def load_content(self, byte_content):
        self.add_page()
        # We assume byte_content includes textual data we can write.
        self.set_font('Arial', size=12)
        self.multi_cell(0, 10, byte_content.decode('utf-8'))

pdf = PDF()
pdf.load_content(pdf_bytes)
pdf.output('output.pdf')

The ‘output.pdf’ file is created and saved, and contains the content from the bytes decoded as text.

The above snippet demonstrates using the FPDF library to create a PDF and insert content from a bytes object. It assumes the bytes represent text data, which is decoded and inserted into the document.

Bonus One-Liner Method 5: Using Shell Command

For UNIX-based systems, you can leverage the command line to direct bytes to a file, though it’s not strictly Python. Assuming Python is used to pipe out bytes:

Here’s an example:

# This is a shell command and should be run in terminal, not in Python script.
echo 'Python bytes content here' | pdftotext - output.pdf

The terminal will run this command and direct the bytes piped from Python into a file named ‘output.pdf’.

This unconventional one-liner demonstrates how to use UNIX pipeline commands to write bytes to a PDF indirectly. However, this method may need additional error handling and is environment-specific.

Summary/Discussion

  • Method 1: PyPDF2 Library. Strengths are its ability to manipulate PDFs beyond simple writing, offering advanced features when needed. Weaknesses include the dependency on external library installation and potential overhead for simple tasks.
  • Method 2: Using built-in open function. Strengths include simplicity and no external dependencies. Weaknesses: only suitable when byte data represents a complete PDF.
  • Method 3: ReportLab Library. Ideal for dynamically generating PDF content from scratch rather than writing existing bytes; highly customizable. Weakness: external library with potential learning curve for its API.
  • Method 4: FPDF Library. Strengths: easy to use for PDF creation, customizable. Weakness: requires understanding and decoding the byte content appropriately.
  • Bonus Method 5: Shell Command. Strength: simple and quick for UNIX users. Weakness: not portable across different operating systems and requires command-line access.