CODEWITHSUNDEEP
ruby-on-rails-4nestedwhere-clause
Syk
Syk

Reputation: 393

Find_by and where

I got two models

bcase.rb

class Bcase < ActiveRecord::Base
    belongs_to :pimp
    has_many :c_entries, :dependent => :destroy
    has_many :s_entries, :dependent => :destroy
    accepts_nested_attributes_for :c_entries, :s_entries

    validates_uniqueness_of :pimp_id
end

c_entry.rb

class CEntry < ActiveRecord::Base
    belongs_to :bcase
end

And I did following in my console:

irb(main):002:0> b = a.build_bcase
=> #<Bcase id: nil, pimp_id: nil, comment_text: nil, created_at: nil, updated_at
: nil, status: nil>

irb(main):003:0> (1..10).each {|i| b.c_entries.build(:order_no => i)}
=> 1..10

irb(main):004:0> b.c_entries
=> #<ActiveRecord::Associations::CollectionProxy [#<CEntry id: nil, bcase_id: ni
l, order_no: 1, description: nil, hours: nil, nrc: nil, created_at: nil, updated
_at: nil>, #<CEntry id: nil, bcase_id: nil, order_no: 2, description: nil, hours
: nil, nrc: nil, created_at: nil, updated_at: nil>, #<CEntry id: nil, bcase_id:
nil, order_no: 3, description: nil, hours: nil, nrc: nil, created_at: nil, updat
ed_at: nil>, #<CEntry id: nil, bcase_id: nil, order_no: 4, description: nil, hou
rs: nil, nrc: nil, created_at: nil, updated_at: nil>, #<CEntry id: nil, bcase_id
: nil, order_no: 5, description: nil, hours: nil, nrc: nil, created_at: nil, upd
ated_at: nil>, #<CEntry id: nil, bcase_id: nil, order_no: 6, description: nil, h
ours: nil, nrc: nil, created_at: nil, updated_at: nil>, #<CEntry id: nil, bcase_
id: nil, order_no: 7, description: nil, hours: nil, nrc: nil, created_at: nil, u
pdated_at: nil>, #<CEntry id: nil, bcase_id: nil, order_no: 8, description: nil,
 hours: nil, nrc: nil, created_at: nil, updated_at: nil>, #<CEntry id: nil, bcas
e_id: nil, order_no: 9, description: nil, hours: nil, nrc: nil, created_at: nil,
 updated_at: nil>, #<CEntry id: nil, bcase_id: nil, order_no: 10, description: n
il, hours: nil, nrc: nil, created_at: nil, updated_at: nil>]>

So, I created an object of the bcase-type with the name "b" and then build 10 objects of the c_entry-type and the :order_no from 1 to 10. And b.c_entries shows me that it worked fine.

Now I was trying to get a single object out of this array with find_by_order_no(1) or where(:order_no => 1) and thats what I get.

irb(main):018:0> b.c_entries.where(:order_no => 1)
=> #<ActiveRecord::Relation []>

irb(main):025:0> b.c_entries.find_by_order_no(1)
=> nil

And that didnt give me what I wanted and I couldnt find out what I did wrong. I also tried to use .first but that didnt help.

irb(main):026:0> b.c_entries.find_by_order_no(1).first
NoMethodError: undefined method `first' for nil:NilClass
        from (irb):26
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-4.0.0
/lib/rails/commands/console.rb:90:in `start'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-4.0.0
/lib/rails/commands/console.rb:9:in `start'
        from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/railties-4.0.0
/lib/rails/commands.rb:64:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

irb(main):027:0> b.c_entries.where(:order_no => 1).first
=> nil

irb(main):028:0> b.c_entries.first
=> #<CEntry id: nil, bcase_id: nil, order_no: 1, description: nil, hours: nil, n
rc: nil, created_at: nil, updated_at: nil>

irb(main):029:0> b.c_entries.first.order_no
=> 1

Anyone knows what to do?

Best regards!

Upvotes: 0

Views: 63

Answers (2)

Carsen
Carsen

Reputation: 183

When you are saying 

b = a.build_bcase

it is just equivalent to 

Bcase.new

Check this: http://apidock.com/rails/ActiveRecord/Relation/build.

What you should be doing is save the record by calling b.save or try create

http://apidock.com/rails/ActiveRecord/Base/create/class

Upvotes: 1

dre-hh
dre-hh

Reputation: 8044

You did not save any of them into the database. Build, only creates stuff in memory. Either call save on build models or use create

Upvotes: 1

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