I know how to check an attribute for errors:
#post.errors[:title].any?
Is it possible to check which validation failed (for example "uniqueness")?
Recently I came across a situation where I need the same thing: The user can add/edit multiple records at once from a single form.
Since at validation time not all records have been written to the database I cannot use #David's solution. To make things even more complicated it is possible that the records already existing in the database can become duplicates, which are detected by the uniqueness validator.
TL;DR: You can't check for a specific validator, but you can check for a specific error.
I'm using this:
# The record has a duplicate value in `my_attribute`, detected by custom code.
if my_attribute_is_not_unique?
# Check if a previous uniqueness validator has already detected this:
unless #record.errors.added?(:my_attribute, :taken)
# No previous `:taken` error or at least a different text.
#record.errors.add(:my_attribute, :taken)
end
end
Some remarks:
It does work with I18n, but you have to provide the same interpolation parameters to added? as the previous validator did.
This doesn't work if the previous validator has written a custom message instead of the default one (:taken)
Regarding checking for uniqueness validation specifically, this didn't work for me:
#post.errors.added?(:title, :taken)
It seems the behaviour has changed so the value must also be passed. This works:
#post.errors.added?(:title, :taken, value: #post.title)
That's the one to use ^ but these also work:
#post.errors.details[:title].map { |e| e[:error] }.include? :taken
#post.errors.added?(:title, 'has already been taken')
Ref #34629, #34652
By "taken", I assume you mean that the title already exists in the database. I further assume that you have the following line in your Post model:
validates_uniqueness_of :title
Personally, I think that checking to see if the title is already taken by checking the validation errors is going to be fragile. #post.errors[:title] will return something like ["has already been taken"]. But what if you decide to change the error message or if you internationalize your application? I think you'd be better off writing a method to do the test:
class Post < ActiveRecord::Base
def title_unique?
Post.where(:title => self.title).count == 0
end
end
Then you can test if the title is unique with #post.title_unique?. I wouldn't be surprised if there's already a Rubygem that dynamically adds a method like this to ActiveRecord models.
If you're using Rails 5+ you can use errors.details. For earlier Rails versions, use the backport gem: https://github.com/cowbell/active_model-errors_details
is_duplicate_title = #post.errors.details[:title].any? do |detail|
detail[:error] == :uniqueness
end
Rails Guide: http://guides.rubyonrails.org/active_record_validations.html#working-with-validation-errors-errors-details
Related
What is the best way to ensure that a model exists before doing string interpolation? I have a variable user, and I need to see what the user's major is. A table in between named user_attributes has the user's info.
#{user.user_attribute.major.name}
The user may not have specified a major yet, in which case they wouldn't have a major model instance yet. So when I try and get the name of the major, I would get an "undefined method on nil class type" error. Any advice on how to safely do this?
You could avoid try and add a method to your model or decorator..
def major_name
user_attribute.major && user_attribute.major.name
end
OR
def major_name
user_attribute.major.name if user_attribute.major?
end
Check: https://codereview.stackexchange.com/questions/28610/handling-nil-trying-to-avoid-try
You can use try method:
# if model is present
{user.user_attribute.major.try(:name)} # => "<MAJOR_NAME>"
# if model is NOT present
{user.user_attribute.major.try(:name)} # => ""
You can read more about try.
You could use the lonely operator. It is like try, but slightly less functional (which doesn't matter in your case).
user.user_attribute.major&.name
This might well be the 'worst' answer to ruby puritans, but it works for me in some scenarios:
"#{user.user_attribute.major.name rescue nil}"
I have an if statement in my update action in one of my controllers. It looks like this:
if !#bid.attributes.values.include?(nil)
build(#bid.id)
end
I am checking to see if there are any nil valued attributes in my Bid object before building a bid report. I know the build method works fine because it builds a report when not wrapped in the if statement. When it is wrapped in this if statement, it doesn't run. I have checked to make sure that there are no nil values in the object. I went into the rails console and all attributes have non-nil values. In addition, I am able to check this in the views to confirm that there are no nil values.
I have also tried writing as:
build(#bid.id) unless #bid.attributes.values.include?(nil)
and a couple other variations. None are allowing the build to run.
Your code seems fine, I'm betting it's your data that's the problem instead. Mostly likely, assuming this an active record instance, the attribute is id which will be nil until the new record gets saved.
What do you get in the terminal when you add this line right before your if?
puts #bid.attributes.to_yaml
You should be able to see what has values and what does not. And I'm pretty sure at least one of those values is nil.
I would recommend being more explicit about exactly which fields are required. And this is exactly what validations are for.
class Person < ActiveRecord::Base
validates :name, presence: true
end
You explicitly validate each field so that when it's absent you get a very specific error message about why: "Person name can't be blank." So instead of wondering why it wont save, you get told why at the point it fails to save.
If you need to code a considerably complex validation, the error sometimes doesnt lie in a particular attribute, but in a combination of several of them.
For example, if i want to validate that a the time period between :start_date and :end_date doesnt contain any sunday, the error doesnt belong specifically to either of those fields, but the Errors add method requires to specify it.
Try doing something like this:
# Your Model.rb
validate :my_own_validation_method
...
private
def my_own_validation_method
if there_is_no_sunday_in_the_range
self.errors[:base] << "You must have a Sunday in the time range!"
end
end
Basically, you can add your own complex validations to a model, and when you see that something erroneous has happened, you can add an error string in the array of errors.
model_instance.errors[:base] << "msg"
The answers above are outdated. For Rails 5 and higher you need to call the ActiveModel::Errors add method with :base as the first parameter. See the example below.
model_instance.errors.add(
:base,
:name_or_email_blank,
message: "either name or email must be present"
)
You can use errors[:base] to add general errors that aren't specifically tied to one attribute - rails guide link.
You can actually name the hash key whatever you'd like:
instance.errors[:case_of_the_sundays] << "Error, son."
Just a little more descriptive.
Update:
message array in order to add an error is deprecated.
Now we do something like that.
self.errors.add(:some_key, "Some Error!")
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).
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?
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"]
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.
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
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
What's the best practices way to test that a model is valid in rails?
For example, if I have a User model that validates the uniqueness of an email_address property, how do I check that posting the form returned an error (or better yet, specifically returned an error for that field).
I feel like this should be something obvious, but as I'm quickly finding out, I still don't quite have the vocabulary required to effectively google ruby questions.
The easiest way would probably be:
class UserEmailAddressDuplicateTest < ActiveSupport::TestCase
def setup
#email = "test#example.org"
#user1, #user2 = User.create(:email => #email), User.new(:email => #email)
end
def test_user_should_not_be_valid_given_duplicate_email_addresses
assert !#user2.valid?
end
def test_user_should_produce_error_for_duplicate_email_address
# Test for the default error message.
assert_equal "has already been taken", #user2.errors.on(:email)
end
end
Of course it's possible that you don't want to create a separate test case for this behaviour, in which case you could duplicate the logic in the setup method and include it in both tests (or put it in a private method).
Alternatively you could store the first (reference) user in a fixture such as fixtures/users.yml, and simply instantiate a new user with a duplicate address in each test.
Refactor as you see fit!
http://thoughtbot.com/projects/shoulda/
Shoulda includes macros for testing things like validators along with many other things. Worth checking out for TDD.
errors.on is what you want
http://api.rubyonrails.org/classes/ActiveRecord/Errors.html#M002496
#obj.errors.on(:email) will return nil if field is valid, and the error messages either in a String or Array of Strings if there are one or more errors.
Testing the model via unit tests is, of course, step one. However, that doesn't necessarily guarantee that the user will get the feedback they need.
Section 4 of the Rails Guide on Testing has a lot of good information on functional testing (i.e. testing controllers and views). You have a couple of basic options here: check that the flash has a message in it about the error, or use assert_select to find the actual HTML elements that should have been generated in case of an error. The latter is really the only way to test that the user will actually get the message.