python string format keyError

Question

I'm getting the following error while trying to execute my script

 ]""".format(id="123", name="test")
KeyError: '\n    "id"'

Here's my script. I just need to format a multiline string. I tried using a dictionary in the format section but that didn't work either.

import requests

payload = """[
  {
    "id":{id},
    "name": "{name}"
  }
]""".format(id="123", name="test")

headers = {"Content-Type": "application/json"}
r = requests.post("http://localhost:8080/employee", data=payload, 
headers=headers)
print(r.status_code, r.reason)

Use the json module to avoid problems. In fact, requests can do that for you. Don't try and format a json string yourself. — user707650
– user707650, Commented Mar 12, 2018 at 22:31
For the issue itself: escape the braces that aren't part of the formatting: """[\n {{\n "id"...\n }}\n]""". — user707650
– user707650, Commented Mar 12, 2018 at 22:32
It's in the stdlib documentation for the json module, the requests documentation for how requests can take care of it by itself. — user707650
– user707650, Commented Mar 12, 2018 at 22:33

Brendan Abel · Accepted Answer · 2018-03-12 22:34:05Z

8

When using format, literal {'s and }'s need to be escaped by doubling them

payload = """[
  {{
    "id":{id},
    "name": "{name}"
  }}
]

""".format(id="123", name="test")

answered Mar 12, 2018 at 22:34

Brendan Abel

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Comments

YSelf · Accepted Answer · 2018-03-12 22:34:17Z

5

You have opening and closing brackets. Format interprets them as a placeholder, you as a dict. Its content is, as the error says, \n "id":{id}… and so on. If you do not mean { as a placeholder, double them.
You are trying to write json yourself. Don't to that. Use the json module:
```
json.dumps({"id": "123", name: "test"})
```
Or even better: Let requests do that.

answered Mar 12, 2018 at 22:34

YSelf

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Comments

Vimanyu · Accepted Answer · 2018-03-12 22:32:53Z

-1

Try using %s instead of .format()

This works:

import requests

payload = """[
  {'id':%s,'name': %s
}
]"""%("123","test")

headers = {"Content-Type": "application/json"}
r = requests.post("http://localhost:8080/employee", data=payload,
headers=headers)
print(r.status_code, r.reason)

answered Mar 12, 2018 at 22:32

Vimanyu

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5 Comments

user707650 Over a year ago

That's usable as a work-around, but doesn't solve the actual underlying issue.

Vimanyu Over a year ago

@Evert: OP wrote in the question "I just need to format a multiline string" and I provided a way. I don't think the solution is incorrect and thus doesn't deserve the downvote!

Vimanyu Over a year ago

@Evert: Sorry, I don't understand which values I didn't quote. I pasted the code after I was successfully able to run the code on my machine. (Obviously 8080 returned "Connection refused" but there is no syntax error.

Vimanyu Over a year ago

Got it! nice catch

Vimanyu Over a year ago

Let us continue this discussion in chat.

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