I have a postgresql table with column defined as: numeric(20,7)
If I insert the value 0 it saves it as: 0.0000000
When I assign this value to Python (2.7) it shows me 0E-7 which is correct but a wrong format.
Why does it shows it like this? and how can I fix it?
You can format a Decimal simply by passing it to:
"{:f}".format(Decimal("0E-7"))
The Decimal supports advanced string formatting:
# PEP 3101 support. the _localeconv keyword argument should be
# considered private: it's provided for ease of testing only.
def __format__(self, specifier, context=None, _localeconv=None):
"""Format a Decimal instance according to the given specifier.
The specifier should be a standard format specifier, with the
form described in PEP 3101. Formatting types 'e', 'E', 'f',
'F', 'g', 'G', 'n' and '%' are supported. If the formatting
type is omitted it defaults to 'g' or 'G', depending on the
value of context.capitals.
"""
By default it seems to use the precision of the Decimal itself:
>>> '{:f}'.format(Decimal('0E-7'))
'0.0000000'
>>> '{:f}'.format(Decimal('0E-8'))
'0.00000000'
>>> '{:f}'.format(Decimal('0E-9'))
'0.000000000'
If on the other hand you want to use a custom precision, pass it in the format string:
>>> print("{:.2f}".format(Decimal("0E-7")))
0.00
For an explanation on what the different letters in the format mean, consult the "Format Specification Mini-Language".
If you want to control the way a float number is formatted, you could try:
"{0:.2f}".format(n) # n is value read from db
.<precision>f sets the precision of the float. I think pablo chose 2 points arbitrarily.