missing-format-string-key / E1304¶

Message emitted:

Missing key %r in format string dictionary

Description:

Used when a format string that uses named conversion specifiers is used with a dictionary that doesn't contain all the keys required by the format string.

Problematic code:

# +1: [missing-format-string-key]
fruit_prices = """
Apple: %(apple_price)d ¤
Orange: %(orange_price)d ¤
""" % {"apple_price": 42}

Correct code:

fruit_prices = """
Apple: %(apple_price)d ¤
Orange: %(orange_price)d ¤
""" % {
    "apple_price": 42,
    "orange_price": 87,
}

Created by the string checker.