Rails 4.1 enum raises error instead set object as invalid

Question

I am using the Rails 4.1 enum field

class User
    enum category: [ :client, :seller, :provider ]
end

When the user signs up, he chooses from a select box his category. The default is empty, because I want to force the user to choose one option.

If the user does not select any option, I would like to return to the form with a validation message. Here is the select box code in sign up form

    <%= f.select :category, [], {}, class: "form-control" do  %>
        <option value="99">Choose an option</option>

        <% User.categories.each do |cat,code| %>
            <option value="<%= code %>" <% if params["user"] && code.to_s == params["user"]["category"] %>selected='selected'<%end%> ><%= t(cat) %></option>
        <% end %>
    <% end %>

When the controller creates the user, instead of adding a validation error to the record, it raises an exception. How to avoid this?

ArgumentError - '99' is not a valid category:
  (gem) activerecord-4.1.1/lib/active_record/enum.rb:103:in `block (3 levels) in enum'
  (gem) activerecord-4.1.1/lib/active_record/attribute_assignment.rb:45:in `_assign_attribute'
  (gem) activerecord-4.1.1/lib/active_record/attribute_assignment.rb:32:in `block in assign_attributes

score 4 · Answer 1 · answered May 30 '16 at 10:56

I really dislike the reasoning as stated in the issue listed above. Since the value is coming over the wire, it should be treated the same as a freetext input where the expectation is to validate in the model and not the controller. This is especially true in APIs where the developers have even less of a say as far as expected input coming from form data (for example).

In case anyone wants a hack, here is what I came up with. Passes basic testing, but would love feedback if anyone finds issues with it:

class User
  enum category: [ :client, :seller, :provider ]

  def category=(val)
    super val
  rescue
    @__bad_cat_val = val
    super nil
  end
end

This will reset category to nil and we can then validate the field:

class User
...
  validates :category, presence: true
end

The problem is that we really want to be validating inclusion, not just presence. To get around that we have to capture the input (e.g. as above in def category=). Then we can output our message using that value:

class User
...
  validates :category, inclusion: { 
    in: categories.keys, 
    message: ->(record,error) {
      val = record.instance_variable_get(:@__bad_cat_val)
      return "Category is required" if val.nil?
      "#{val.inspect} is not a valid category"
    }
  }
end

That will give us messages for presence and inclusion. If you need to fine tune it more you would have to use a custom validator (I believe).

Here's another workaround option: https://stackoverflow.com/a/58416806/47185 (extracted as a concern so it's more reusable) — Tyler Rick, Dec 02 '19 at 23:48

Roman Kiselenko · Answer 2 · 2015-08-17T21:19:27.453

1

The enum in Rails always raise a error if you try to set an invalid value. There is no such validation and add an error message to base or adding a validation error to the record. You should create own validation by rescue errors.

=> u = User.last
=> User.genders
=> {"male"=>0, "female"=>1}
=> u.gender = 'boy'
#> ArgumentError: 'boy' is not a valid gender
=> u.gender = 'male'
#> "male"

edited Aug 17 '15 at 21:19

answered Jul 28 '14 at 16:03

Roman Kiselenko

43,210
9
91
103

I don't know how to catch this error. In my Model file. I tried to create my own validation. def industry_must_be_valid if(self.industry != nil) begin if(User.industries[self.industry] != nil) return true else errors.add(:industry, "is not valid") return false end rescue Exception => e errors.add(:industry, "is not valid") return false end end – FlyingV Nov 30 '15 at 20:01

score 1 · Answer 3 · answered Dec 05 '14 at 17:41

1

Read: https://github.com/rails/rails/issues/13971

Specifically read Senny's comment:

The current focus of AR enums is to map a set of states (labels) to an integer for performance reasons. Currently assigning a wrong state is considered an application level error and not a user input error. That's why you get an ArgumentError.

That being said you can always set nil or an empty string to the enum attribute without raising an error:

<option value="">Choose an option</option>

and add a simple presence validation like:

validates :category, presence: { message: "is required" }

answered Dec 05 '14 at 17:41

DanielBlanco

69
1
4

What if an entry like "Orange" is submitted, which is not part of the enum values. An exception will be thrown. In your validates function within the model, how would you check for this? – FlyingV Nov 30 '15 at 20:06
In that case I think the best approach is to validate **:category** params in the controller, and check if the received value is within the enum values. If it isn't we can just default to nil and let the model validation take care. – DanielBlanco Dec 02 '15 at 14:23

score -1 · Answer 4 · answered Mar 28 '16 at 14:20

-1

In case someone still struggles with this. You can add a standard inclusion validation like this (in the User model):

validates :category, inclusion: { 
            in: categories.keys, 
            message: "%{value} is not a valid category"
          }

answered Mar 28 '16 at 14:20

Kamen

681
3
10

1

@developer033 yep, this example does not work. this one -› https://github.com/CristiRazvi/enum_attributes_validation although being a gem, does work – Ben Mar 31 '18 at 14:29

Rails 4.1 enum raises error instead set object as invalid

4 Answers4