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Al Rowan

2010-Oct-11 20:33 UTC

Nooby Stuck - "has_and_belongs_to_many" relationship

trying to set up a "has_and_belongs_to_many" relationship

would very much appreciate the help, not sure what im doing wrong at all. 

Scheme.rb

class Scheme < ActiveRecord::Base
  
  validates :schemename, :presence => true
  belongs_to :user
  has_many :levels, :dependent => :destroy
  
    has_and_belongs_to_many :works

end

Work.rb


class Work < ActiveRecord::Base

  validates :workname, :presence => true
  
  belongs_to :user
  belongs_to :unit
  has_many :marks
  has_and_belongs_to_many :schemes

end

migration for schemes_works

class CreateSchemesWorks < ActiveRecord::Migration
def self.up
  create_table :schemes_works, :id => false do |t| 
    t.references :scheme 
    t.references :work
end

THE ERROR
>> scheme = Scheme.last=> #<Scheme id: 21, schemename: "another", colour: nil, share:
nil, subject_id: nil, user_id: 2, created_at: "2010-10-05 08:17:03",
updated_at: "2010-10-05 08:17:03">>> work = Work.last=> #<Work id: 5, workname: "thrd", unit_id: 4, user_id: nil,
unit: nil, created_at: "2010-10-11 17:24:51", updated_at:
"2010-10-11 17:24:51">>> scheme.works << workActiveRecord::StatementInvalid: SQLite3::SQLException: near ")":
syntax error: INSERT INTO "schemes_works" () VALUES ()
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:202:in
`log''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/sqlite_adapter.rb:135:in
`execute''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:263:in
`insert_sql''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/sqlite_adapter.rb:149:in
`insert_sql''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:44:in
`insert''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/query_cache.rb:16:in
`insert''
  from
/Library/Ruby/Gems/1.8/gems/arel-1.0.1/lib/arel/engines/sql/engine.rb:30:in
`create''
  from
/Library/Ruby/Gems/1.8/gems/arel-1.0.1/lib/arel/algebra/relations/writes.rb:24:in
`call''
  from /Library/Ruby/Gems/1.8/gems/arel-1.0.1/lib/arel/session.rb:17:in
`create''
  from
/Library/Ruby/Gems/1.8/gems/arel-1.0.1/lib/arel/algebra/relations/relation.rb:159:in
`insert''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/has_and_belongs_to_many_association.rb:70:in
`insert_record''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:136:in
`<<''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:479:in
`add_record_to_target_with_callbacks''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:135:in
`<<''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:133:in
`each''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:133:in
`<<''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:158:in
`transaction''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:139:in
`transaction''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/transactions.rb:204:in
`transaction''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:157:in
`transaction''
  from
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:132:in
`<<''
  from (irb):4>>
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Marnen Laibow-Koser

2010-Oct-11 20:46 UTC

head link

Re: Nooby Stuck - "has_and_belongs_to_many" relationship

On Oct 11, 4:33 pm, Al Rowan
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:> trying to set up a "has_and_belongs_to_many" relationship
>
> would very much appreciate the help, not sure what im doing wrong at all.
>
> Scheme.rb
>
> class Scheme < ActiveRecord::Base
>
>   validates :schemename, :presence => true
Just :name.  There''s no need to repeat your table name in your field
names.
>   belongs_to :user
>   has_many :levels, :dependent => :destroy
>
>     has_and_belongs_to_many :works
>
> end
>
> Work.rb
>
> class Work < ActiveRecord::Base
>
>   validates :workname, :presence => true
Again, just :name.
>
>   belongs_to :user
>   belongs_to :unit
>   has_many :marks
>   has_and_belongs_to_many :schemes
>
> end
You have User, Unit, and Mark already defined, right?
>
> migration for schemes_works
>
> class CreateSchemesWorks < ActiveRecord::Migration
> def self.up
>   create_table :schemes_works, :id => false do |t|
>     t.references :scheme
>     t.references :work
> end
This generally looks good so far.  Make sure you install the Foreigner
gem so you can easily put foreign key constraints in your
DB.>
> THE ERROR
>
> >> scheme = Scheme.last
>
> => #<Scheme id: 21, schemename: "another", colour: nil,
share: nil, subject_id: nil, user_id: 2, created_at: "2010-10-05
08:17:03", updated_at: "2010-10-05 08:17:03">>> work =
Work.last
>
> => #<Work id: 5, workname: "thrd", unit_id: 4, user_id:
nil, unit: nil, created_at: "2010-10-11 17:24:51", updated_at:
"2010-10-11 17:24:51">>> scheme.works << work
>
> ActiveRecord::StatementInvalid: SQLite3::SQLException: near ")":
syntax error: INSERT INTO "schemes_works" () VALUES ()
That''s peculiar.  Seems like Rails is not generating the right SQL to
send to the DB.  I gather you''re doing this from the Rails console;
have you restarted it since adding the classes and running the
migrations given above?  If not, then do so and see if the problem
persists.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

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Marnen Laibow-Koser

2010-Oct-11 20:52 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

After posting, I looked again, and I think I see your problem.

On Oct 11, 4:33 pm, Al Rowan
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:
[...]> migration for schemes_works
>
> class CreateSchemesWorks < ActiveRecord::Migration
> def self.up
>   create_table :schemes_works, :id => false do |t|
>     t.references :scheme
>     t.references :work
> end
>
> THE ERROR
[...]> ActiveRecord::StatementInvalid: SQLite3::SQLException: near ")":
syntax error: INSERT INTO "schemes_works" () VALUES ()
Notice the empty first pair of parentheses there.  The field names
should go there (that is, the query should look like
INSERT INTO "schemes_works" (scheme_id, work_id) VALUES (21, 5)
), so presumably Rails doesn''t realize there are any fields in that
table.  Now the question is *why*.

Take a look at the schemes_works table in your DB.  Does it have
scheme_id and work_id fields?

Take a look at your db/schema.rb file, specifically the part
describing the schemes_works table.  Does it have those fields?

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

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Al Rowan

2010-Oct-12 09:34 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

I had done a "reload!" before doing those console commands, i even 
rebooted! lol

my schemes_work table contains a scheme and work field only. not 
scheme_id nor work_id should i change them? i was following the 
configuration from a tutorial where they did the same. so i just assumed 
that was right. ill rename them now and see if it solves it. it does 
make sense! lol

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Al Rowan

2010-Oct-12 09:49 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

could it be because i''ve used "t.refrences" and not
"t.integer"


I only say this because, I tried to rename the columns and it threw up 
the error "Missing column schemes_works.scheme"

using

def self.up
rename_column :schemes_works, :scheme, :scheme_id
rename_column :schemes_works, :work, :work_id
end

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Al Rowan

2010-Oct-12 10:02 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

ok so, i added the "_id" to both..same error. i also changed it from 
refrences to integer and it gave me the same error.

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Al Rowan

2010-Oct-12 12:35 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

dont know if this helps at all..



?> scheme.works.empty?
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: 
schemes_works.scheme_id: SELECT     * FROM       "works"  INNER JOIN 
"schemes_works" ON "works".id =
"schemes_works".work_id WHERE
("schemes_works".scheme_id = 21 )
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:202:in
`log''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/sqlite_adapter.rb:135:in
`execute''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/sqlite_adapter.rb:284:in
`select''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in
`select_all''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/connection_adapters/abstract/query_cache.rb:56:in
`select_all''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/base.rb:467:in 
`find_by_sql''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/relation.rb:64:in
`to_a''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/relation/finder_methods.rb:143:in
`all''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:70:in
`find''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/base.rb:1128:in
`with_scope''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_proxy.rb:203:in
`send''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_proxy.rb:203:in
`with_scope''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:63:in
`find''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:467:in
`find_target''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:409:in
`load_target''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/has_and_belongs_to_many_association.rb:33:in
`count_records''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:300:in
`size''
  from 
/Library/Ruby/Gems/1.8/gems/activerecord-3.0.0/lib/active_record/associations/association_collection.rb:319:in
`empty?''
  from (irb):10>>

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Al Rowan

2010-Oct-12 12:54 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

solved that last error by changing it back from the extra "_id"

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Al Rowan

2010-Oct-12 15:10 UTC

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Re: Nooby Stuck - "has_and_belongs_to_many" relationship

through some strange coincidence, my mac crashed. after a reboot it now 
all works. sorry for wasting your marnen and thanks very much for your 
assistance. I''m quite stumped as to what actually triggered the fix, I 
haven''t done anything really. I am using Aptana Studio 3...(still in 
beta) perhaps something strange is going on with it.

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