fstring in JSON, ValueError: Invalid format specifier, Python

Question

I have the following code:

import json

domain="abc.com"

rawlog = json.loads(
            f'{"domain": ${domain}}')
            
print(rawlog["domain"])

Which gives me:

Traceback (most recent call last):
  File "<string>", line 6, in <module>
ValueError: Invalid format specifier
>

The question is, what is the cause and if I can have fstring in Json? I'm using the newest Python: python3 --version shows Python 3.10.4.

I also tried:

import json

domain="abc.com"

rawlog = json.loads('{"domain": f'{domain}'}')
            
print(rawlog["domain"])

but it gives:

File "<string>", line 5
    rawlog = json.loads('{"domain": f'domain'}')
                                      ^
SyntaxError: invalid syntax

Daweo · Accepted Answer · 2022-08-11 08:27:18Z

2

As { and } have special meaning they need to be escaped to mean literal { and literal }, consider following simple example

import json
domain="abc.com"
string=f'{{"domain": "{domain}"}}'
parsed=json.loads(string)
print(parsed)

gives output

{'domain': 'abc.com'}

answered Aug 11, 2022 at 8:27

Daweo

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