Cannot execute stored procedure in Rails 3 and mysql2 gem

Hi All,

Suppose I have a stored procedure named procedure().

Running ActiveRecord::Base.connection.execute(“CALL procedure()”) will
give you a bunch of errors in different cases while using mysql2 adapter
like:

ActiveRecord::StatementInvalid: Mysql2::Error: PROCEDURE can’t return a
result set in the given context: procedure() PROCEDURE

or

ActiveRecord::StatementInvalid: Mysql2::Error: Commands out of sync; you
can’t run this command now.

How can The problem be solved? Need Assistance.

Best Regards,

Nirmalya Ghosh

Hello Nirmalya,

It’s a very important question which you have right now, fortunately I
think I know the answer, here I am giving you the solution —

Solution :
When MySQL runs stored procedure it has to know that client can handle
multiple result sets.

We will create patch file for that in our initializer folder of our
application.

Create mysql2_adapter.rb file in config/initializers with the following
content:

module ActiveRecord
class Base

Overriding ActiveRecord::Base.mysql2_connection

method to allow passing options from database.yml

Example of database.yml

login: &login

socket: /tmp/mysql.sock

adapter: mysql2

host: localhost

encoding: utf8

@param [Hash] config hash that you define in your

database.yml

@return [Mysql2Adapter] new MySQL adapter object

def self.mysql2_connection(config)
config[:username] = ‘root’ if config[:username].nil?

if Mysql2::Client.const_defined? :FOUND_ROWS
  config[:flags] = config[:flags] ? config[:flags] |

Mysql2::Client::FOUND_ROWS : Mysql2::Client::FOUND_ROWS
end

client = Mysql2::Client.new(config.symbolize_keys)
options = [config[:host], config[:username], config[:password],

config[:database], config[:port], config[:socket], 0]
ConnectionAdapters::Mysql2Adapter.new(client, logger, options,
config)
end

def self.find_by_sp(sql)
connection.select_sp(sanitize_sql(sql), “#{name} Load”).collect! {
|record| instantiate(record) }
end
end

module ConnectionAdapters
class Mysql2Adapter < AbstractMysqlAdapter
# This method is for running stored procedures.
#
# @param [String] the name of procedure
# and arguments for procedure
# @return [Hash]
#
def select_sp(sql, name = nil)
connection = ActiveRecord::Base.connection
begin
connection.select_all(sql, name)
rescue NoMethodError
ensure
connection.reconnect! unless connection.active?
end
end
end
end
end

If by some reason MySQL drops connection after executing stored
procedure, then we have to restore it before doing anything else. For
that purpose we have created the select_sp(sql, name = nil).

This method does several things:

  • it intercepts NoMethodError that could be raised when your procedure
    returns nothing
  • it restores connection if it was dropped

So now you can run ActiveRecord::Base.procedure(“CALL procedure()”)
without any errors and get a hash with results.

I think it will help you.

Best Regards,
Zinia Dutta Gupta.

Thanks Zinia for the reply and I think I got the answer.

Thanks Again.

Best Regards,

Nirmalya Ghosh

Zinia Dutta Gupta wrote in post #1141735:

Hello Nirmalya,

Solution :
When MySQL runs stored procedure it has to know that client can handle
multiple result sets.

We will create patch file for that in our initializer folder of our
application.

Create mysql2_adapter.rb file in config/initializers with the following
content:

module ActiveRecord
class Base

Overriding ActiveRecord::Base.mysql2_connection

method to allow passing options from database.yml

Example of database.yml

login: &login

socket: /tmp/mysql.sock

adapter: mysql2

host: localhost

encoding: utf8

@param [Hash] config hash that you define in your

database.yml

@return [Mysql2Adapter] new MySQL adapter object

def self.mysql2_connection(config)
config[:username] = ‘root’ if config[:username].nil?

if Mysql2::Client.const_defined? :FOUND_ROWS
  config[:flags] = config[:flags] ? config[:flags] |

Mysql2::Client::FOUND_ROWS : Mysql2::Client::FOUND_ROWS
end

client = Mysql2::Client.new(config.symbolize_keys)
options = [config[:host], config[:username], config[:password],

config[:database], config[:port], config[:socket], 0]
ConnectionAdapters::Mysql2Adapter.new(client, logger, options,
config)
end

def self.find_by_sp(sql)
connection.select_sp(sanitize_sql(sql), “#{name} Load”).collect! {
|record| instantiate(record) }
end
end

module ConnectionAdapters
class Mysql2Adapter < AbstractMysqlAdapter
# This method is for running stored procedures.
#
# @param [String] the name of procedure
# and arguments for procedure
# @return [Hash]
#
def select_sp(sql, name = nil)
connection = ActiveRecord::Base.connection
begin
connection.select_all(sql, name)
rescue NoMethodError
ensure
connection.reconnect! unless connection.active?
end
end
end
end
end

If by some reason MySQL drops connection after executing stored
procedure, then we have to restore it before doing anything else. For
that purpose we have created the select_sp(sql, name = nil).

This method does several things:

  • it intercepts NoMethodError that could be raised when your procedure
    returns nothing
  • it restores connection if it was dropped

So now you can run ActiveRecord::Base.procedure(“CALL procedure()”)
without any errors and get a hash with results.

Best Regards,
Zinia Dutta Gupta.

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