How to change change error messages on rails - ruby-on-rails

Question

My view:
<div class="form-group">
<% if #product.errors.details[:amount].any? %>
<div class="has-error">
<%= f.label "#{t('product.shineer_irsen')}", class: 'control-label' %>
<%= f.number_field :amount, value: 0, min: 0, class: "form-control" %>
</div>
<% else %>
<%= f.label "#{t('product.shineer_irsen')}", class: 'control-label' %>
<%= f.number_field :amount, value: 0, min: 0, class: "form-control" %>
<% end %>
</div>
I want to validate amount in input field and i want to change its error message into my native language.
Now, error message is
error message
How to change it? please help me.
Product model:
class Product < ApplicationRecord
belongs_to :item
belongs_to :user
belongs_to :branch
validates :amount, numericality: {greater_than_or_equal_to: 0}
def item_name
item.try(:name)
end
def item_name=(query)
self.item = Item.find_by_name(query) if query.present?
end
def amount=(new_value)
if read_attribute(:amount)
#old_amount = read_attribute(:amount)
write_attribute(:amount, new_value.to_i + #old_amount)
else
write_attribute(:amount, new_value.to_i)
end
end
end
some line of local/mn.yml
activerecord:
attributes:
...
errors:
models:
subcategory:
attributes:
category_id:
invalid: "ahaha"
blank: "хоосон байж болохгүй"
category:
blank: "сонгоогүй байна."
product:
attributes:
amount:
greater_than_or_equal_to: 'Оруулах утга 0-ээс их байх ёстой.'

Answer 1

I suppose you want to translate "Value must be grater than or equal to 0", if that's the case, what you need to do is create a translation for that on the locale file. In Spanish will be something like this:
# config/locales/es.yml
es:
activerecord:
errors:
models:
product:
attributes:
amount:
greater_than_or_equal_to: 'What ever you want to say'
Depending on your native language, you have to create the file and define the message, I think you are doing it already, because you are using translations:
#{t('product.shineer_irsen')}
You can find more information here:
http://guides.rubyonrails.org/i18n.html#translations-for-active-record-models

Answer 2

You can customize the error message that you get from a model validation, in this case you need to add to your Model:
validates :age, numericality: {greater_than_or_equal_to: 0, message: 'Este campo tiene que ser positivo' }
With this, you dont need to change the view.