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excsm

2012-Sep-25 13:58 UTC

[activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

Hi,

I initially sent this idea as a github 
issue: https://github.com/rails/rails/issues/7753 (closed)

Steve Klabnik suggested I should post here first (better late than never).

I''ve since created a PR: https://github.com/rails/rails/pull/7755

Original discussion:
=============

I''m using the relatively new --standalone feature/option of bundler so
as
to avoid extracting a part of my rails project into a separate project. My 
only requirement is to not have to load rails entirely:

By creating a custom gemfile (subset of your typical gemfile) and executing:

    bundle install --gemfile=Gemfile.my_subset --standalone

bundler will create a ruby script which requires all the gems in your 
gemfile subset using the
original gems locations.

e.g. :

    path = File.expand_path(''..'', __FILE__)
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/rake-0.9.2.2/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/multi_json-1.0.4/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/activesupport-3.1.6/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/builder-3.0.3/lib")
    $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/i18n-0.6.0/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/activemodel-3.1.6/lib")
    $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/arel-2.2.3/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/tzinfo-0.3.33/lib")
    $:.unshift 
File.expand_path("#{path}/../ruby/1.9.1/gems/activerecord-3.1.6/lib")
    ...

This allows scripts to e.g. load just activerecord without setting up a 
separate
gemfile.

The issue here is that with this setup script, you aren''t using bundler
(to
avoid loading rails and 
the gems in your typical gemfile.). Additionally, the gems the script 
requires are `expanded` gems
and have not been installed via `gem install`.

Activerecord connection adapters have this code:

    gem ''mysql2'', ''~> 0.3.10''
    require ''mysql2''

This code assumes:

  * You''re running the code within bundler (recommended)
  * You have the mysql2 gem installed as a gem in your system

When using bundler standalone neither of these cases are true so the app 
breaks with:

   Please install the mysql2 adapter: `gem install 
activerecord-mysql2-adapter` (no such file to load -- 
active_record/connection_adapters/mysql2_adapter)
because it hits the ''gem'' call before it attempts to require
''mysql2''

IMHO a better approach would be:

    begin
      require ''mysql2''
    rescue LoadError
      gem ''mysql2'', ''~> 0.3.10''
      require ''mysql2''
    end

This code assumes you already have mysql2 on your load path somehow and 
only if it raises an exception do we attempt to issue the `gem` call.

Is this reasonable?

Regards,

Saimon

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Aaron Patterson

2012-Sep-25 17:33 UTC

head link

Re: [activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

On Tue, Sep 25, 2012 at 06:58:45AM -0700, excsm wrote:> Hi,
> 
> I initially sent this idea as a github 
> issue: https://github.com/rails/rails/issues/7753 (closed)
> 
> Steve Klabnik suggested I should post here first (better late than never).
> 
> I''ve since created a PR: https://github.com/rails/rails/pull/7755
> 
> Original discussion:
> =============> 
> 
> I''m using the relatively new --standalone feature/option of
bundler so as
> to avoid extracting a part of my rails project into a separate project. My 
> only requirement is to not have to load rails entirely:
> 
> By creating a custom gemfile (subset of your typical gemfile) and
executing:
> 
>     bundle install --gemfile=Gemfile.my_subset --standalone
> 
> bundler will create a ruby script which requires all the gems in your 
> gemfile subset using the
> original gems locations.
> 
> e.g. :
> 
>     path = File.expand_path(''..'', __FILE__)
>     $:.unshift 
> File.expand_path("#{path}/../ruby/1.9.1/gems/rake-0.9.2.2/lib")
>     $:.unshift 
>
File.expand_path("#{path}/../ruby/1.9.1/gems/multi_json-1.0.4/lib")
>     $:.unshift 
>
File.expand_path("#{path}/../ruby/1.9.1/gems/activesupport-3.1.6/lib")
>     $:.unshift 
> File.expand_path("#{path}/../ruby/1.9.1/gems/builder-3.0.3/lib")
>     $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/i18n-0.6.0/lib")
>     $:.unshift 
>
File.expand_path("#{path}/../ruby/1.9.1/gems/activemodel-3.1.6/lib")
>     $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/arel-2.2.3/lib")
>     $:.unshift 
> File.expand_path("#{path}/../ruby/1.9.1/gems/tzinfo-0.3.33/lib")
>     $:.unshift 
>
File.expand_path("#{path}/../ruby/1.9.1/gems/activerecord-3.1.6/lib")
>     ...
> 
> This allows scripts to e.g. load just activerecord without setting up a 
> separate
> gemfile.
> 
> The issue here is that with this setup script, you aren''t using
bundler (to
> avoid loading rails and 
> the gems in your typical gemfile.). Additionally, the gems the script 
> requires are `expanded` gems
> and have not been installed via `gem install`.
> 
> Activerecord connection adapters have this code:
> 
>     gem ''mysql2'', ''~> 0.3.10''
>     require ''mysql2''
> 
> This code assumes:
> 
>   * You''re running the code within bundler (recommended)
>   * You have the mysql2 gem installed as a gem in your system
> 
> When using bundler standalone neither of these cases are true so the app 
> breaks with:
> 
>    Please install the mysql2 adapter: `gem install 
> activerecord-mysql2-adapter` (no such file to load -- 
> active_record/connection_adapters/mysql2_adapter)
> because it hits the ''gem'' call before it attempts to
require ''mysql2''
> 
> IMHO a better approach would be:
> 
>     begin
>       require ''mysql2''
>     rescue LoadError
>       gem ''mysql2'', ''~> 0.3.10''
>       require ''mysql2''
>     end
> 
> This code assumes you already have mysql2 on your load path somehow and 
> only if it raises an exception do we attempt to issue the `gem` call.
If you have mysql2 on your system, the `gem` call will never be made
(defeating the purpose of the `gem` call in the first place).
> Is this reasonable?
If we don''t use the `gem` command, we can''t enforce a
particular version
of mysql2 in the adapter code.  Since AR has "soft dependencies"
(dependencies that are not declared in the gemspec), we need some way to
ensure that we''ve loaded a connection handling gem that has the version
we actually support.  Doing a `require ''mysql2''` could pick up
*any*
version of mysql2, including one that won''t actually work with the
AR adapter code.

-- 
Aaron Patterson
http://tenderlovemaking.com/

Saimon Moore

2012-Sep-27 09:10 UTC

head link

Re: [activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

Hi Aaron,

On 25/09/2012, at 19:33, Aaron Patterson <tenderlove@ruby-lang.org> wrote:
> On Tue, Sep 25, 2012 at 06:58:45AM -0700, excsm wrote:
>> Hi,
>> 
>> I initially sent this idea as a github 
>> issue: https://github.com/rails/rails/issues/7753 (closed)
>> 
>> Steve Klabnik suggested I should post here first (better late than
never).
>> 
>> I''ve since created a PR:
https://github.com/rails/rails/pull/7755
>> 
>> Original discussion:
>> =============>> 
>> 
>> I''m using the relatively new --standalone feature/option of
bundler so as
>> to avoid extracting a part of my rails project into a separate project.
My
>> only requirement is to not have to load rails entirely:
>> 
>> By creating a custom gemfile (subset of your typical gemfile) and
executing:
>> 
>>    bundle install --gemfile=Gemfile.my_subset --standalone
>> 
>> bundler will create a ruby script which requires all the gems in your 
>> gemfile subset using the
>> original gems locations.
>> 
>> e.g. :
>> 
>>    path = File.expand_path(''..'', __FILE__)
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/rake-0.9.2.2/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/multi_json-1.0.4/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/activesupport-3.1.6/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/builder-3.0.3/lib")
>>    $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/i18n-0.6.0/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/activemodel-3.1.6/lib")
>>    $:.unshift
File.expand_path("#{path}/../ruby/1.9.1/gems/arel-2.2.3/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/tzinfo-0.3.33/lib")
>>    $:.unshift 
>>
File.expand_path("#{path}/../ruby/1.9.1/gems/activerecord-3.1.6/lib")
>>    ...
>> 
>> This allows scripts to e.g. load just activerecord without setting up a
>> separate
>> gemfile.
>> 
>> The issue here is that with this setup script, you aren''t
using bundler (to
>> avoid loading rails and 
>> the gems in your typical gemfile.). Additionally, the gems the script 
>> requires are `expanded` gems
>> and have not been installed via `gem install`.
>> 
>> Activerecord connection adapters have this code:
>> 
>>    gem ''mysql2'', ''~> 0.3.10''
>>    require ''mysql2''
>> 
>> This code assumes:
>> 
>>  * You''re running the code within bundler (recommended)
>>  * You have the mysql2 gem installed as a gem in your system
>> 
>> When using bundler standalone neither of these cases are true so the
app
>> breaks with:
>> 
>>   Please install the mysql2 adapter: `gem install 
>> activerecord-mysql2-adapter` (no such file to load -- 
>> active_record/connection_adapters/mysql2_adapter)
>> because it hits the ''gem'' call before it attempts to
require ''mysql2''
>> 
>> IMHO a better approach would be:
>> 
>>    begin
>>      require ''mysql2''
>>    rescue LoadError
>>      gem ''mysql2'', ''~> 0.3.10''
>>      require ''mysql2''
>>    end
>> 
>> This code assumes you already have mysql2 on your load path somehow and
>> only if it raises an exception do we attempt to issue the `gem` call.
> 
> If you have mysql2 on your system, the `gem` call will never be made
> (defeating the purpose of the `gem` call in the first place).
> 
>> Is this reasonable?
> 
> If we don''t use the `gem` command, we can''t enforce a
particular version
> of mysql2 in the adapter code.  Since AR has "soft dependencies"
> (dependencies that are not declared in the gemspec), we need some way to
> ensure that we''ve loaded a connection handling gem that has the
version
> we actually support.  Doing a `require ''mysql2''` could
pick up *any*
> version of mysql2, including one that won''t actually work with the
> AR adapter code.
I understand though I think it sucks…

What about something like:

    begin
       gem ''mysql2'', ''~> 0.3.11''
       require ''mysql2''
    rescue LoadError
      puts "You do not appear to have mysql2 (~> 0.3.11) installed. AR
requires this to function correctly."

      begin 
        require ''mysql2''
        puts "Found some version of mysql2. Proceeding..."
      rescue LoadError => err
        raise err
      end
    end

Then you leave the responsibility up to the developer…
> 
> -- 
> Aaron Patterson
> http://tenderlovemaking.com/
Saimon



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Rails core - Sep 2012 - [activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

[activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

Re: [activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone

Re: [activerecord] Better loading pattern for connection adapters that play nicely with bundler --standalone