How to replace a double quote with a backwards slash preceded by a double quote

Question

I am trying to send a HTML file via through the payload of a HTTP request in Python.

If I pass the following HTML file then there are no problems as long as I remove the n and t characters.

    <!DOCTYPE html>
    <html>
        <body>
            <h1>My First Heading</h1>
            <p>My first paragraph.</p>
        </body>
    </html>

However, if I include any tags that have double quotes (e.g. <img src="w3schools.jpg" alt="W3Schools.com" width="104" height="142">) then the HTML breaks the JSON format of the payload that I am sending and my request to the server returns a 404.

My payload currently looks something like this:

payload = f'{{"foo":"","bar":[],"html":"{html_file}"}}'.encode('utf-8')

I need my HTML to look like this for it to be processed properly:

    <!DOCTYPE html>
    <html>
        <body>
            <h1>My First Heading</h1>
            <p>My first paragraph.</p>
            <img src="w3schools.jpg" alt="W3Schools.com" width="104" height="142">
        </body>
    </html>

Asked By: knowledge_seeker

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Source

Answer 1

Don’t try to do the quoting yourself. Python has a json module for producing valid json, and it does all the right quoting for you. Use that!

Answered By: psmears

Answer 2

No need to hand craft your JSON. You could build a python dict and use the json module to do the encoding. Quotes, newlines and any other troublesome characters will get the proper escaping.

import json
html_file = """<!DOCTYPE html>
    <html>
        <body>
            <h1>My First Heading</h1>
            <p>My first paragraph.</p>
            <img src="w3schools.jpg" alt="W3Schools.com" width="104" height="142">
        </body>
    </html>"""

payload = json.dumps({"foo":"","bar":[],"html":html_file}).encode("utf-8")

Answered By: tdelaney

How to replace a double quote with a backwards slash preceded by a double quote

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