Customise message for validates_uniqueness_of

I am trying to convert an integer to a DAYNAME in my validation message

validates_uniqueness_of :day, scope: :store, :message => “already has a target for #{Date::DAYNAMES[self.day]}.”

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This does not seem to work, I cannot access the day value.

The following displays the correct value

validates_uniqueness_of :day, scope: :store, :message => “already has a target for %{value}.”

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This throws an error:

validates_uniqueness_of :day, scope: :store, :message => “already has a target for #{Date::DAYNAMES[%{value}]}.”

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Any help would be Amazing!

Using double quotes with #{} will definitely not do what you want; the interpolation will be attempted at class-load time, not when the string is needed.

The value passed to :message is handed off to I18n.translate, so the docs for that may be some help.

It may be easier (and clearer) to just define a custom validation function that does what you want.

–Matt Jones

This is along the lines of what Matt is referring to.

class DayValidator < ActiveRecord::Validator def validate() if YOUR_TEST_FOR_INVALIDITY(record.day) date = Date::DAYNAMES[record.day] record.errors[:day] << “already has a target #{date}” end end end

class YourClass < ActiveRecord::Base validates_with DayValidator end

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