Format: KeyError when using curly brackets in strings

Question

I\'m running the following code:

asset = {}
asset[\'abc\'] = \'def\'
print type(asset)
print asset[\'abc\']
query = \'{\"abc\": \"{abc}\"}\'.format(abc=asset         


        

Answer 1

To insert a literal brace, double it up:

query = '{{"abc": "{abc}"}}'.format(abc=asset['abc'])

(This is documented here, but not highlighted particularly obviously).

Answer 2

The topmost curly braces are interpreted as a placeholder key inside your string, thus you get the KeyError. You need to escape them like this:

asset = {}
asset['abc'] = 'def'
query = '{{"abc": "{abc}"}}'.format(**asset)

And then:

>>> print query
{"abc": "def"}

Answer 3

wrap the outer braces in braces:

query = '{{"abc": "{abc}"}}'.format(abc=asset['abc'])
print query
{"abc": "def"}