python's json: AttributeError: 'str' object has no attribute 'keys'

Question

I am trying to load a string (the actual program read this line from a file and it is a very large file that I can not manually modify) formatted as a dictionary.

I need to convert the string line into a json object so I can check value of specific key, e.g. myJson[Date] .

This is the script:

import json

mystring = "{'Date': 'Fri, 19 Apr 2019 03:58:04 GMT', 'Server': 'Apache/2.4.39', 'Accept-Ranges': 'bytes'}"


mystring = json.dumps(mystring)
myJson = json.loads(mystring)

print(str(myJson.keys()))
print(str(myJson))

I am getting this error:

AttributeError: 'str' object has no attribute 'keys'

I suspect that the mystring format is not conforming and that the single quotes should be double quotes? Given that I have a large data, and I can not simply replace single colons with double one using simple search/replace as single colons may be included in the values which I should not modify. If this is the cause of the problem, is there any way to replace the colons of the key/value pair only without touching the colons in the values? I am hoping that this is not the problem.

Solution 1

Rather than dealing with the single quoted string and struggling to convert it into json, just use ast package to convert it into a valid dict.

import ast

mystring = "{'Date': 'Fri, 19 Apr 2019 03:58:04 GMT', 'Server': 'Apache/2.4.39', 'Accept-Ranges': 'bytes'}"

my_dict = ast.literal_eval(mystring)

the result is:

> print(my_dict["Date"])
Fri, 19 Apr 2019 03:58:04 GMT

Solution 2

This code stores the string as a dictionary in a variable called "Tempvar" From that variable you can just use the keys like a regular dictionary.

import json

mystring = "{'Date': 'Fri, 19 Apr 2019 03:58:04 GMT', 'Server': 'Apache/2.4.39', 'Accept-Ranges': 'bytes'}"

exec("tempvar = " + mystring)
mystring = json.dumps(mystring)
myJson = json.loads(mystring)

print(str(tempvar['Date']))
print(str(myJson))

Hope this helps

Comments

[user9371654]

Are you sure the mystring.replace will replace only the key/value commas? Not any other commas inside the value?

[Ricardo Wong]

the replace command replaces single quotes with double quotes, not the commas. You can print the result of the replace command only, to see how it works

[user9371654]

Yes I mean quotes. that was a typo. But as I said, the data in the values may contain double quotes. This is dangerous to blindly replace quotes. Unless there isa method that can guarantee that only key/value quotes get replaces.

[Ricardo Wong]

ohh I see your concern... ast.literal_eval is a more practical solution in this particular case

[user9371654]

I mean inside the value, it is possible that I have single quotes that should remain. Example: 'Date': 'Fri, '19' Apr 2019 03:58:04 GMT'. I should not change the quotes in 19. Or possibly there will be double quotes like Example: 'Date': 'Fri, "19" Apr 2019 03:58:04 GMT' which I do not know if will cause problems if I converted the single quotes to double quotes?

[Ricardo Wong]

The problem with that string is that will be interpreted as two different values with something in the middle like 'Fri, ' 19 and ' Apr 2019... '. The other case is easy to solve with an extra par of replacements