Rails: Multiple if conditions in validation

Question

Using: Rails 3.0.3

I have validations such as this one:

  validates_numericality_of :person_weight_kg, :greater_than => 0, :message => "value_must_be_number_over_zero", :if => :bmi_calculation?, :if => :is_metric?

That I would like to validate for multiple if-conditions (such as in the example). But it seems, however, that Rails treats these statements as OR. One returns false and one returns true which makes the validation go through.

So, how do I check that this validation fulfills BOTH if-statements (bmi_calculation AND is_metric)?

It also doesn't treat them as OR. The second :if overrides the first one. — mikdiet
– mikdiet, Commented Dec 13, 2019 at 10:04

tokland · Accepted Answer · 2016-11-09 19:11:24Z

53

Use a lambda as the if condition:

validates_numericality_of :person_weight_kg, 
  if: -> record { record.bmi_calculation? && record.is_metric? }

edited Nov 9, 2016 at 19:11

answered Oct 4, 2011 at 10:31

tokland

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3 Comments

Aboozar Rajabi Over a year ago

It doesn't work in Rails 5. Do you have any solution?

CamiloVA Over a year ago

maybe because it should declare the parameter inside the lambda block if: -> { |record| record.bmi_calculation? && record.is_metric? }

Joshua Pinter Over a year ago

Update for 2024: if: proc{ |record| record.bmi_calculation? && record.is_metric? }

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