I have a rails model which has 7 numeric attributes filled in by the user via a form.
I need to validate the presence of each of these attributes which is obviously easy using
validates :attribute1, :presence => true
validates :attribute2, :presence => true
# and so on through the attributes
However I also need to run a custom validator which takes a number of the attributes and does some calculations with them. If the result of these calculations is not within a certain range then the model should be declared invalid.
On it's own, this too is easy
validate :calculations_ok?
def calculations_ok?
errors[:base] << "Not within required range" unless within_required_range?
end
def within_required_range?
# check the calculations and return true or false here
end
However the problem is that the method "validate" always gets run before the method "validates". This means that if the user leaves one of the required fields blank, rails throws an error when it tries to do a calculation with a blank attribute.
So how can I check the presence of all the required attributes first?
Best Answer
I'm not sure it's guaranteed what order these validations get run in, as it might depend on how the
attributes
hash itself ends up ordered. You may be better off making yourvalidate
method more resilient and simply not run if some of the required data is missing. For example:This will bail out if any of the variables
a
throughd
are blank, which includes nil, empty arrays or strings, and so forth.