get property of a model data

rubyonrails-talk
1

Rails 3.1.3

This must be a simple matter, but since I am stupid enough to misunderstand something.

In a controller, I would like to create AND search for another model if they match in terms of the properties.

  def create     @take = current_user.takes.build(params[:take])

    # search for matches     @result = Item.where(:flight_name => @take.flight_name,                          :flight_num => @take.flight_num,                          :departure => @take.departure,                          :check_in => @take.check_in,                          :weight => @take.weight)

    if @result.exists?       if @result.user_id != current_user.id #<---HERE!!!!

...

I need to check if the searched 'Item' does not have the same 'user_id' with the current logged-in user. So I need to get the 'user_id' field of @result. But certainly, putting '@result.user_id' gives an error.

How was I supposed to get 'user_id' from the @result object?

soichi

2

The problem may be at exists?

What's the status of the @result object? Is it nil? Does it have any value? What do you get if you inspect it or print it? What's the exact error you get?

3

Looking at ruby docs, this is the explanation for the method - Evaluates to true if this resource is not new? and is found on the remote service. Using this method, you can check for resources that may have been deleted between the object’s instantiation and actions on it.

http://apidock.com/rails/ActiveResource/Base/exists%3F

In your situation you should be doing a nil check rather than exists check.

4

What's the status of the @result object? Is it nil? Does it have any value?

Since it passed the if part, 'if @result.exists?', @result does exist. I have confirmed that.

What's the exact error you get?

The error is simply

undefined method `user_id' for

5

Item has a "belongs_to :user", right?

In any case, what do you get when you print or inspect @result?

6

Pradeep Singh wrote in post #1075257:

Item has a "belongs_to :user", right?

yes

In any case, what do you get when you print or inspect @result?

if I print it,

#<ActiveRecord::Relation:0x00000100f24800>

is what I get.

7

Try @result.to_yaml to see its attributes

8

Try @result.to_yaml to see its attributes

I got the following

#<ActiveRecord::Relation:0x00000100dedae0>--- - !ruby/object:Take   attributes:     id: 8     flight_name: soichi     flight_num: 1111     departure: 2012-09-21     check_in: true     weight: 5     created_at: 2012-09-10 02:16:05.691104000 Z     updated_at: 2012-09-10 02:16:05.691104000 Z     user_id: 2

9

sorry, 'Item' is actually named 'Take' here.

10

I see, so the object you're getting is of type Relation.

Just for kicks I tried this in rails console for my own Item class. Same thing happens to me - no method user_id.

You need to get the item object from the @result object. This works -

item = @result.first item.user_id

There might be better ways though.

11

item = @result.first item.user_id

It worked fine! Thank you very much. Now I need to study 'type Relation' :slight_smile:

soichi

12

The reason it did not work originally is that @result is not a single record, it is all the records that match the where clause. In practice it may be only one but it will still be returned in, effectively, an array. Hence the need to use .first to get the first one.

Colin