Turning python object with special character to JSON string object

Question

I have gone through a lot of examples in stack overflow that are related to this kind of issue but none of those answers worked for my problem. I have a string inside a variable which contains the escape single backslash character "\". I am concatenating that string variable to a JSON string variable. Then doing json.loads() on that json string but I am getting an error:

ValueError: Expecting , delimiter: line 1 column 41 (char 40)

This is my code:

import json 

# The string of pass_string is taken from a rest/api/content of a website
pass_string = "I am an \"Engineer\""
data = '{"data": {"test": 1, "hello": "' + pass_string + ' in this lifetime."}, "id": 4}'

json_data = json.loads(data)
print(json_data)

Since pass_string is taken from a request.get() function from a website it is not possible to turn that into a raw string and then input into our data like:

pass_string = r"I am an \"Engineer\""

The above does work but my string is being passed inside the variable pass_string so I would have to modify the contents inside the variable somehow. Tried a lot of examples from stack overflow but none seem to work for my case.

Answer 1

json.loads needs a string representation of the escape, so you need to escape the escape:

import json 

pass_string = "I am an \"Engineer\"".replace('\"', '\\"')
data = '{"data": {"test": 1, "hello": "' + pass_string + ' in this lifetime."}, "id": 4}'

json_data = json.loads(data)
print(json_data)

Output:

{'data': {'test': 1, 'hello': 'I am an "Engineer" in this lifetime.'}, 'id': 4}

Answer 2

Just stop trying to create JSON strings manually. That is your fundamental problem. Use the python data structures then serialize that to the string at the end using the json module.

So start with something like:

>>> import json
>>> data = {"data": {"test": 1, "hello": " in this lifetime."}, "id": 4}

Then simply:

>>> pass_string = "I am an \"Engineer\""
>>> data['data']['hello'] = pass_string + data['data']['hello']
>>> print(data)
{'data': {'test': 1, 'hello': 'I am an "Engineer" in this lifetime.'}, 'id': 4}
>>> print(json.dumps(data))
{"data": {"test": 1, "hello": "I am an \"Engineer\" in this lifetime."}, "id": 4}

Although, since you are passing it to requests.put as the data argument, you don't have to use json.dumps at all... You haven't been very clear, I think you actually start with a JSON string,

data = '{"data": {"test": 1, "hello": " in this lifetime."}, "id": 4}'

So what you should do is just:

data = json.loads(data)
data['data']['hello'] = pass_string + data['data']['hello']

And voilá. You can now just do requests.put(url,data=data)