💡 Problem Formulation: Converting byte arrays in Python to PDF files is a common task when dealing with binary data streams that represent PDF documents. This could stem from downloading a PDF file, manipulating it in memory, or receiving it as part of an API response. The ideal input is a byte array containing PDF binary data, and the desired output is a properly formatted, saved PDF file on the filesystem.
Method 1: Using PyPDF2
PyPDF2 is a Pure-Python library built as a PDF toolkit. It is capable of extracting document information, splitting documents, merging documents, and more. With PyPDF2, you can take a byte array that represents a PDF and write it directly to a file on the system. This method is straightforward and powerful when working with PDFs in Python.
Here’s an example:
from PyPDF2 import PdfFileReader, PdfFileWriter
import io
# Assume 'pdf_bytes' is the byte array containing your PDF data
pdf_bytes = b'%PDF-1.4 ... endobj xref ... %%EOF'
# Convert byte array to a file-like object
pdf_buffer = io.BytesIO(pdf_bytes)
# Read the PDF
pdf = PdfFileReader(pdf_buffer)
# Prepare to write the PDF to file
pdf_writer = PdfFileWriter()
# Add all pages to the writer
for page in range(pdf.numPages):
pdf_writer.addPage(pdf.getPage(page))
# Write out the PDF to a file
with open('output.pdf', 'wb') as f:
pdf_writer.write(f)
Output of the code snippet will be a file named ‘output.pdf’ containing the PDF data from the byte array.
This code snippet initializes a PdfFileReader object for reading the PDF and a PdfFileWriter object for writing to a file. It copies each page from the reader to the writer and then finally writes the PDF content to ‘output.pdf’.
Method 2: Using ReportLab
ReportLab is a library that allows for generating PDFs from scratch. While typically used for creating new documents, it can also be used to write a byte array to a PDF file should you need to combine this task with PDF generation. For simplicity, we will only demonstrate saving to a PDF file.
Here’s an example:
from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import letter
import io
# Your byte array (normally you'd get this from a file, API, etc.)
pdf_bytes = b'%PDF-1.4 ... endobj xref ... %%EOF'
# Create a file-like buffer to receive PDF data
buffer = io.BytesIO(pdf_bytes)
# Create a canvas
c = canvas.Canvas(buffer, pagesize=letter)
# Do any drawing or writing to the canvas here if necessary
# For example: c.drawString(100, 750, "Welcome to ReportLab!")
# Save the PDF to the buffer
c.save()
# Seek to the beginning and write buffer to a file
with open('output_from_reportlab.pdf', 'wb') as f:
f.write(buffer.getvalue())
The output is a new PDF file called ‘output_from_reportlab.pdf’ with the content of the byte array.
This snippet uses ReportLab to create a PDF canvas, which you normally use to draw text and graphics onto the PDF. Here, we simply take the byte array and write it to the canvas buffer, then save the contents to a file.
Method 3: Using a File Write
For a simple byte array to PDF conversion, Python’s built-in file write feature can be used. This is Python’s simplest approach and requires minimal setup since you’re working directly with file streams.
Here’s an example:
pdf_bytes = b'%PDF-1.4 ... endobj xref ... %%EOF'
# Simple byte array to pdf file write
with open('simple_output.pdf', 'wb') as file:
file.write(pdf_bytes)
The code writes the byte array to ‘simple_output.pdf’ creating a readable PDF file.
This snippet opens a file in binary write mode and directly writes the byte array to the file. The resulting file is then a PDF that can be opened with any PDF reader.
Method 4: Using fpdf2
fpdf2 is a minimalist PDF creation library for Python that also allows for writing existing PDF content. The variety of methods fpdf2 offers can be useful for more intricate PDF manipulation, as well as straight byte array to PDF conversion.
Here’s an example:
from fpdf import FPDF
import io
pdf_bytes = b'%PDF-1.4 ... endobj xref ... %%EOF'
class PDF(FPDF):
def __init__(self, pdf_bytes):
super().__init__()
self.pdf_bytes = pdf_bytes
def header(self):
# Any header processing you want
pass
def footer(self):
# Any footer processing you want
pass
def add_pdf_from_bytes(self):
self.set_auto_page_break(0)
self.add_page()
self.set_xy(0, 0)
self.multi_cell(0, 10, self.pdf_bytes.decode('latin-1'))
# Create the PDF object
pdf = PDF(pdf_bytes)
# Add the byte array as PDF content
pdf.add_pdf_from_bytes()
# Output to a file
pdf.output('output_from_fpdf2.pdf')
The generated file ‘output_from_fpdf2.pdf’ will contain your converted PDF content.
This snippet creates a custom class extending FPDF to include a method for adding content from a byte array. It then decodes the byte array (assuming ‘latin-1’ encoding for the PDF text) and places it into a cell within the document.
Bonus One-Liner Method 5: Using write()
Employing the Python built-in ‘write()’ function, converting a byte array to PDF can be as simple as a one-liner. This method is highly efficient and straightforward when there is no need for additional PDF manipulation.
Here’s an example:
open('one_liner_output.pdf', 'wb').write(b'%PDF-1.4 ... endobj xref ... %%EOF')
The ‘one_liner_output.pdf’ file now reflects the contents of the byte array as a PDF.
This one-liner opens the file and writes the byte array to it in a single operation, effectively flushing the data to disk as a PDF without additional steps.
Summary/Discussion
- Method 1: PyPDF2. Suitable for additional PDF processing needs. Requires an external library. Potentially slower due to per-page handling.
- Method 2: ReportLab. Best when PDF generation is also involved. Might be overkill for simple write operations. Introduces more complexity.
- Method 3: File Write. Fast and built-in, no external dependencies. Lacks features for any advanced PDF manipulations.
- Method 4: fpdf2. Good for integrating with PDF creation workflows. The requirement to decode the byte array could introduce encoding issues.
- Method 5: Write(). Efficient for a quick write without frills. Not suitable for any form of PDF content manipulation or error handling.