how to customize rails activerecord validation error message to show attribute value

Question

When a user tries to create a record with a name that already exists, I want to show an error message like:

name "some name" has already been taken

I have been trying to do:

validates_uniqueness_of :name, :message => "#{name} has already been taken"

but this outputs the table name instead of the value of the name attribute

Austin Taylor · Accepted Answer · 2011-05-20 14:37:59Z

46

2 things:

The validation messages use the Rails I18n style interpolation, which is %{value}
The key is value rather than name, because in the context of internationalization, you don't really care about the rest of the model.

So your code should be:

validates_uniqueness_of :name, :message => '%{value} has already been taken'

answered May 20, 2011 at 14:37

Austin Taylor

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2 Comments

Dylan Markow Over a year ago

Nice! Definitely cleaner than my answer.

zwalker Over a year ago

It may be useful to know that %{attribute} is also available for use.

Dylan Markow · Accepted Answer · 2011-05-20 14:35:22Z

26

It looks like you can pass a Proc to the message. When you do this, you get two parameters:

A symbol along the lines of :activerecord.errors.models.user.attributes.name.taken
A hash that looks something like `{:model=>"User", :attribute=>"Name", :value=>"My Name"}

So if you allow for two parameters on a proc, you can use the attributes[:value] item to get the name that was used:

validates_uniqueness_of :name, 
                        :message => Proc.new { |error, attributes| 
                          "#{attributes[:value]} has already been taken." 
                        }

answered May 20, 2011 at 14:35

Dylan Markow

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1 Comment

Joshua Pinter Over a year ago

In Rails 7.1, the first param is the object.

Sergio Kozlov · Accepted Answer · 2011-05-20 14:38:41Z

3

What version of Rails do you use?

If Rails 3. then as i understand you should use :message => '%{value} has already been taken'. I am not sure about Rails 2.3. - but in any case you can create your own custom validation that performs what you need.

answered May 20, 2011 at 14:38

Sergio Kozlov

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1 Comment

umar Over a year ago

for this application, i am using rails 2.3.4

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