Adding an error message to a custom validator

Question

I have a custom validator and I am trying to output an error message when it fails but have been unable to do so. Could someone please tell me if I am doing this in the correct place. ``` class User < ActiveRecord::Base self.table_name = "user" attr_accessible :name, :ip, :printer_port, :scanner_port validates :name, :presence => true, :length => { :maximum => 75 }, :uniqueness => true validates :ip, :length => { :maximum => 75 }, :allow_nil => true validates :printer_port, :presence => true, :if => :has_association? validates :scanner_port, :presence => true, :if => :has_association? def has_association? ip != nil end end ``` I had it as follows: ``` validates :printer_port, :presence => true, :message => "can't be blank", :if => :has_wfm_association? ``` But was receiving an error ``` Unknown validator: 'MessageValidator' ``` And when I tried to put the message at the end of the validator the comma seperating the has_association? turned the question mark and comma orange

Accepted Answer

The `message` and `if` parameters should be inside a hash for `presence`:

```
validates :printer_port, :presence => {:message => "can't be blank", :if => :has_wfm_association?}
```

This is because you can load multiple validations in a single line:

```
validates :foo, :presence => true, :uniqueness => true
```

If you tried to add a message to that the way you did, or an `if` condition, Rails wouldn't know what validation to apply the message/conditional to. So instead, you need to set the message per-validation:

```
validates :foo, :presence => {:message => "must be present"},
                :uniqueness => {:message => "must be unique"}
```

Adding an error message to a custom validator

Solution

Problem