The code that ended up allowing everything to run properly is as follows. Ultimately, I believe the key difference was 'meat: []' in the controller.
Model:
class Order
include Mongoid::Document
field :type, type: String
field :meat, type: Array, default: []
field :cheese, type: Mongoid::Boolean
belongs_to :user
end
Controller:
def create
@order = Order.new(order_params)
if @order.save
redirect_to action: 'index'
flash[:notice] = "Successfully submitted order!"
else
render action: 'new'
end
end
private
def order_params
params.require(:order).permit(:type, :cheese, meat: [])
end
And view:
<%= form_for @order do |f| %>
<div>
<%= f.label :type %>:
<%= f.select :type, ['Burrito', 'Taco', 'Quesadilla', 'Salad Bowl'] %>
</div>
<div>
<%= f.label :meat %>
<%= check_box_tag 'order[meat][]', 'chicken', @order.meat.include?('chicken') %>
<%= check_box_tag 'order[meat][]', 'steak', @order.meat.include?('steak') %>
<%= check_box_tag 'order[meat][]', 'tofu', @order.meat.include?('tofu') %>
</div>
<div>
<%= f.label :cheese %>:
<%= f.check_box :cheese %>Yes
</div>
<div><%= f.submit %></div>
<% end %>
Hope this helps somebody.