从另一张表中获取id，rails

Question

I have a table test having fields 'user_id' and 'post_id'. user_id I fetch by current_user.id and post_id from the post table. For this I do: In test controller:-

def create
  @user = current_user
  @test = Test.new(params[:test])
  @post = Post.find(params[:id])
  @test.post_id = @post.id
  @test.user_id = @user.id
respond_to do |format|
   @test.save
   format.html { redirect_to(:back, :notice => "successfull") }
  else
    format.html { render :action => "new" }
  end
end

In my Models, I create association:-

In test.rb:

 belongs_to :post

In post.rb:

has_many :test

The View page is:

 = form_for @test, :validate => true do |f|
   .span
     = f.text_field :email, :placeholder =>"Email Address"
   .span
     = f.label :name
     = f.text_field :name
   .span
     = f.submit "Save"

The user_id save properly but for post_id it give error:

 Called id for nil, which would mistakenly be 4 -- if you really wanted the id of nil, use object_id

How can I resolve that problem ?

Answer 1

Are you sure you should access the create method only when you are login ie current_user should not be nil.

If you are getting this error in create method only then it should be on line

@test.user_id = @user.id

this is because @user is nil, and you are calling .id on nil .

EDITED

You need to send post_id from your form, assuming you are getting post object in @post

Add following line your view

= form_for @test, :validate => true do |f|
    = hidden_field_tag "post_id", @post.id

and update

@post = Post.find(params[:id])

with

@post = Post.find(params[:post_id])

Answer 2

Is the standard message in Rails that tells you that you tried to invoke .id on a nil value.

I suspect your current_user is nil . You can be sure by raise current_user.inspect i think which will tell you that its nil

You be sure you are logged in so that your current_user is not nil