id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
32761	"Model meta field ""to_python"" behaviour with decimal fields"	aiacamposm	nobody	"When calling {{{to_python}}} method of a model field I expect it returns the exact same value that will be stored in the database, i.e., when saved the instance and retrieved later, to have this same value as the corresponding attribute. However, it doesn't seem to behave correctly when the field is of type DecimalField.

I have a model {{{MyModel}}} that has a field {{{foo}}} with {{{max_digits=10}}} and {{{decimal_places=2}}}, so when I save a value 3.4211 (passed as a common float) the value stored is Decimal(""3.42""). However, if call {{{MyModel._meta.get_field(""foo"").to_python(3.4211)}}}  the result is Decimal(""3.421100000""). 

Inspecting the source code of this method {{{to_python}}} I guess the problem is that it uses decimal.Context with {{{prec}}} equal to the number of {{{max_digits}}}, which is something that only makes sense if the number passed has {{{max_digits}}} meaningful digits.

Should it be changed to return the decimal with the specified number of digits, or am I wrong assuming that {{{to_python}}} should return the exact same value that will be stored?"	Bug	closed	Database layer (models, ORM)	3.2	Normal	duplicate			Unreviewed	0	0	0	0	0	0