Nested model error messages

I am using Ruby on Rails 3.0.9 and I am trying to validate a nested model. Supposing that I run validation for the "main" model and that generates some errors for the nested model I get the following:

@user.valid?

@user.errors.inspect
# => {:"account.firstname"=>["is too short", "can not be blank"], :"account.lastname"=>["is too short", "can not be blank"], :account=>["is invalid"]}

How you can see the RoR framework creates an errors hash having following keys: account.firstname, account.lastname, account. Since I would like to display error messages on the front-end content by handling those error key\value pairs with JavaScript (BTW: I use jQuery) that involves CSS properties I thought to "prepare" that data and to change those keys to account_firstname, account_lastname, account (note: I substitute the . with the _ character).开发者_如何转开发

How can I change key values from, for example, account.firstname to account_firstname?

And, mostly important, how I should handle this situation? Is what I am trying to do a "good" way to handle nested model errors? If no, what is the common\best approach to do that?

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I've made a quick Concern which shows full error messages for nested models:

https://gist.github.com/4710856

#1.9.3-p362 :008 > s.all_full_error_messages
  # => ["Purchaser can't be blank", "Consumer email can't be blank", "Consumer email is invalid", "Consumer full name can't be blank"]

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Some creative patching of the Rails errors hash will let you achieve your aim. Create an initializer in config/initalizers, let call it errors_hash_patch.rb and put the following in it:

ActiveModel::Errors.class_eval do
  def [](attribute)
    attribute = attribute.to_sym
    dotted_attribute = attribute.to_s.gsub("_", ".").to_sym
    attribute_result = get(attribute)
    dotted_attribute_result = get(dotted_attribute)
    if attribute_result 
      attribute_result 
    elsif dotted_attribute_result
      dotted_attribute_result
    else
      set(attribute, [])
    end
  end
end

All you're doing in here is simply overriding the accessor method [] to try a little harder. More specifically, if the key you're looking for has underscores, it will try to look it up as is, but if it can't find anything it will also replace all the underscores with dots and try to look that up as well. Other than that the behaviour is the same as the regular [] method. For example, let's say you have an errors hash like the one from your example:

errors = {:"account.firstname"=>["is too short", "can not be blank"], :"account.lastname"=>["is too short", "can not be blank"], :account=>["is invalid"]}

Here are some of the ways you can access it and the results that come back:

errors[:account] => ["is invalid"]
errors[:"account.lastname"] => ["is too short", "can not be blank"]
errors[:account_lastname] => ["is too short", "can not be blank"]
errors[:blah] => []

We don't change the way the keys are stored in the errors hash, so we won't accidentally break libraries and behaviours that may rely on the format of the the hash. All we're doing is being a little smarter regarding how we access the data in the hash. Of course, if you DO want to change the data in the hash, the pattern is the same you will just need to override the []= method, and every time rails tries to store keys with dots in them, just change the dots to underscores.

As to your second question, even though I have shown you how to do what you're asking, in general it is best to try and comply with the way rails tries to do things, rather than trying to bend rails to your will. In your case, if you want to display the error messages via javascript, presumably your javascript will have access to a hash of error data, so why not tweak this data with javascript to be in the format that you need it to be. Alternatively you may clone the error data inside a controller and tweak it there (before your javascript ever has access to it). It is difficult to give advice without knowing more about your situation (how are you writing your forms, what exactly is your validation JS trying to do etc.), but those are some general guidelines.

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I had the same problem with AngularJs, so I decided to overwrite the as_json method for the ActiveModel::Errors class in an initializer called active_model_errors.rb so that it can replace . for _

Here is the initializer code:

module ActiveModel
  class Errors
    def as_json(options=nil)
      hash = {}
      to_hash(options && options[:full_messages]).each{ |k,v| hash[k.to_s.sub('.', '_')] = messages[k] }
      hash
    end
  end
end

I hope it can be helpful for someone

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I'm not sure but I think you can't change that behavior without pain. But you could give a try to solutions like http://bcardarella.com/post/4211204716/client-side-validations-3-0