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04 May 2012, 15:54
Benjamin Sigidi (2 posts)

Chapter 10 from page 112, i start getting an error

@ActiveModel::MassAssignmentSecurity::Error in LineItemsController#create@

Start complaining about mass assignment on protected atributes. I think it’s the product id, because my addres looks like this

@ @

and the error message looks like this

@ ActiveModel::MassAssignmentSecurity::Error in LineItemsController#create

Can’t mass-assign protected attributes: 2@

attr_accessibleOn my model i have not used #attr_accessible

I am using rails 3.2.3

can someone please help.

01 Jun 2012, 20:15
Mark Rall (1 post)

Chapter 9, page 112 of the PDF has a similar problem.

Can't mass-assign protected attributes: product
app/controllers/line_items_controller.rb:45:in `create'

I’ve tried the advice at theengguy, adding more attr_accessible attributes to the LineItems and Product models - no luck.

ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin11.4.0]
Rails 3.2.3

Please help. Thanks!

07 Jun 2012, 16:33
Jerome Marchand (2 posts)

the order of things done imacts this matter.

I had a similiar issue under iteration D3. My line_item model had attr_accessible :product_id, :cart_id

On a hunch a commented the line out and things passed through. Works, but I don’t know if it may subject to mass-assignment… We’ll see if further on this matter gets addressed with proper handling of the process.

Santafe photo_pragsmall
30 Apr 2013, 23:36
Bradford Arner (1 post)

The create() method in LineItemsController should be as follows:

def create
    @cart = current_cart
    product = Product.find(params[:product_id])
    @line_item =

    respond_to do |format|
        format.html { redirect_to @line_item.cart, notice: 'Line item was successfully created.' }
        format.json { render json: @line_item, status: :created, location: @line_item }
        format.html { render action: "new" }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }

The key difference is what you are passing into the build() method. The book says it should be: @line_item = product)

However, it should be now be: @line_item =

This is to protect against the Mass Assignment security issue. In other words, all that you have to do is clearly identify that you are assigning the to the product_id column in the LineItem table.

I’m not sure if they have updated the book yet but the one that I was going through was from the library, so it may have been a previous edition.

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