保存前检查用户输入

Question

Good Day All!

Edited for better understanding.

First model is Inventory and in this model I have Product_Type, Product_Name and User_ID.

Second model I have Users which consist of First_Name, Last_Name and Pin_Number.

On my Inventories page I have a form for checking out said Product_Type and Product_Name, also a place for a user to put their Pin_Number in. On submit, it will check the Pin_Number they have typed in and validate it in the Users model and if the Pin_Number is correct it will create an entry with said Product_Type, Product_Name and User_ID (which is pulled from Pin_Number that was submitted.)

I am just trying to figure out how to validate that Pin_Number they submitted.

Thats why I thought I had to do some kind of validation and an if statement based on that validation. Not sure how to go about that.

I hope this clears up any confusion.

Answer 1

I am just trying to figure out how to validate that Pin_Number they submitted.

What constitutes a valid pin_number ? Just that it allows you to successfully look up a User ? What if a user enters another user's pin_number ? Is that considered 'valid'? Something to think about...

It would be helpful if you would add to your question what your params look like upon form submission. But, we can do some guess work.

So, let's assume that params looks something like:

{..., "inventory"=>{"product_type"=>"foo", "product_name"=>"Bar"}, "pin_number"=>5, ...}

In your controller, you'll probably do something like:

if @user = User.find_by(pin_number: params[:pin_number])
  @inventory = Inventory.new(inventory_params)
  @inventory.user = @user
  if @inventory.valid?
    @inventory.save
    # perhaps do some other stuff...
  else 
    # handle the case where the `@inventory` is not valid
  end
else
  # handle the case where the `@user` was not found
end

This assumes you have something like:

private 

  def inventory_params
    params.require(:inventory).permit(:product_type, :product_name)
  end

In your Inventory model, you probably want to do something like (I apologize, I'm not on Rails 5 yet, so some of the syntax may be incorrect):

class Inventory < ActiveRecord::Base 

  validates :user_id,
            :product_type,
            :product_name,
            presence: true

  belongs_to :user

end

You probably also want to consider adding an index on User.pin_number if you're going to be doing a lot of finding by it.

Answer 2

Not sure if I got the question right, but sounds like a custom validator to me.

You can learn more about custom validators in the official Rails documentation under " Custom Validators "

Also, consider moving the class for the custom validator you'll build to a concern, which is a great way to make it reusable. You can find more information on this StackOverflow question and this nice tutorial .