There are times when it would be very useful to be able to get the Arel for
any given ActiveRecord action such as a creation or update without actually
carrying out the action.
I''m imagine something like...
the_arel = Fruit.arel{|f|
f.create :name => ''Banana'', :color =>
''Yellow''
}
Does anyone else think this would be nice to have (or know of a way to do
it already)?
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What would the usecase for this be? On 13/01/2013, at 10:46, Steve Jorgensen <stevej@stevej.name> wrote:> There are times when it would be very useful to be able to get the Arel for any given ActiveRecord action such as a creation or update without actually carrying out the action. > > I''m imagine something like... > > the_arel = Fruit.arel{|f| > f.create :name => ''Banana'', :color => ''Yellow'' > } > > Does anyone else think this would be nice to have (or know of a way to do it already)? > -- > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. > To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. > To post to this group, send email to rubyonrails-core@googlegroups.com. > To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. > For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
The use case would be using AR semantics to define an action, but then using that in a larger context, such as concatenating the SQL for several updates together using ";" and executing them in a single round-trip to the server. Technically, this just means just needing the SQL, but it seems silly to provide the SQL rather than the Arel from which the SQL can be trivially retrieved. On Saturday, January 12, 2013 7:47:18 PM UTC-8, Ryan Bigg wrote:> > What would the usecase for this be? > > > > On 13/01/2013, at 10:46, Steve Jorgensen <ste...@stevej.name <javascript:>> > wrote: > > There are times when it would be very useful to be able to get the Arel > for any given ActiveRecord action such as a creation or update without > actually carrying out the action. > > I''m imagine something like... > > the_arel = Fruit.arel{|f| > f.create :name => ''Banana'', :color => ''Yellow'' > } > > Does anyone else think this would be nice to have (or know of a way to do > it already)? > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. > To post to this group, send email to rubyonra...@googlegroups.com<javascript:> > . > To unsubscribe from this group, send email to > rubyonrails-co...@googlegroups.com <javascript:>. > For more options, visit this group at > http://groups.google.com/group/rubyonrails-core?hl=en. > >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/yWAe7JMZ24QJ. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
I think this is way too specific for core. Looks like a great idea for a plugin, though :) Cheers, -foca On 12/01/2013, at 21:57, Steve Jorgensen <stevej@stevej.name> wrote:> The use case would be using AR semantics to define an action, but then using that in a larger context, such as concatenating the SQL for several updates together using ";" and executing them in a single round-trip to the server. Technically, this just means just needing the SQL, but it seems silly to provide the SQL rather than the Arel from which the SQL can be trivially retrieved. > > On Saturday, January 12, 2013 7:47:18 PM UTC-8, Ryan Bigg wrote: >> >> What would the usecase for this be? >> >> >> >> On 13/01/2013, at 10:46, Steve Jorgensen <ste...@stevej.name> wrote: >> >>> There are times when it would be very useful to be able to get the Arel for any given ActiveRecord action such as a creation or update without actually carrying out the action. >>> >>> I''m imagine something like... >>> >>> the_arel = Fruit.arel{|f| >>> f.create :name => ''Banana'', :color => ''Yellow'' >>> } >>> >>> Does anyone else think this would be nice to have (or know of a way to do it already)? >>> -- >>> You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. >>> To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. >>> To post to this group, send email to rubyonra...@googlegroups.com. >>> To unsubscribe from this group, send email to rubyonrails-co...@googlegroups.com. >>> For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en. > -- > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. > To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/yWAe7JMZ24QJ. > To post to this group, send email to rubyonrails-core@googlegroups.com. > To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. > For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
Could that be done as a plugin and not rely on undocumented internal APIs that are likely to change without warning? On Sunday, January 13, 2013 12:02:31 AM UTC-8, Nicolás Sanguinetti wrote:> > I think this is way too specific for core. Looks like a great idea for a > plugin, though :) > > Cheers, > -foca > > On 12/01/2013, at 21:57, Steve Jorgensen <ste...@stevej.name <javascript:>> > wrote: > > The use case would be using AR semantics to define an action, but then > using that in a larger context, such as concatenating the SQL for several > updates together using ";" and executing them in a single round-trip to the > server. Technically, this just means just needing the SQL, but it seems > silly to provide the SQL rather than the Arel from which the SQL can be > trivially retrieved. > > On Saturday, January 12, 2013 7:47:18 PM UTC-8, Ryan Bigg wrote: >> >> What would the usecase for this be? >> >> >> >> On 13/01/2013, at 10:46, Steve Jorgensen <ste...@stevej.name> wrote: >> >> There are times when it would be very useful to be able to get the Arel >> for any given ActiveRecord action such as a creation or update without >> actually carrying out the action. >> >> I''m imagine something like... >> >> the_arel = Fruit.arel{|f| >> f.create :name => ''Banana'', :color => ''Yellow'' >> } >> >> Does anyone else think this would be nice to have (or know of a way to do >> it already)? >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Ruby on Rails: Core" group. >> To view this discussion on the web visit >> https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. >> To post to this group, send email to rubyonra...@googlegroups.com. >> To unsubscribe from this group, send email to >> rubyonrails-co...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/rubyonrails-core?hl=en. >> >> -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/rubyonrails-core/-/yWAe7JMZ24QJ. > To post to this group, send email to rubyonra...@googlegroups.com<javascript:> > . > To unsubscribe from this group, send email to > rubyonrails-co...@googlegroups.com <javascript:>. > For more options, visit this group at > http://groups.google.com/group/rubyonrails-core?hl=en. > >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/guvPfxo1VM0J. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
> > > > What would the usecase for this be? > > > > > > > > > > > > > > > > >I just had a similar need the other day, where I needed to build a separate query based on the current scope (not clone the current scope, but take the specific parameters of the scope to apply to another query which wasn''t a scope at all). The way I had to do what I needed was to grab the current scope and manually inspect the `where_values`, `joins_values`, etc.> > I think this is way too specific for core. Looks like a great idea for a plugin, though :)I don''t disagree that this may be too specific for core. Just demonstrating that I think there''s a need, so might make a good gem.> Could that be done as a plugin and not rely on undocumented internal APIs that are likely to change without warning?I would think so. Looking at the AR code for creating a record, https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb#L32 you can trace the actual save down to this line: https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb#L436 and if you look at the line above it, you get an array of Arel::Attributes values from this method: https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods.rb#L323 which is just doing this (and note this method is protected, not private): attrs = {} arel_table = self.class.arel_table attribute_names.each do |name| attrs[arel_table[name]] = typecasted_attribute_value(name) end attrs If you just want the array of attributes, then you could do the above and combine it with Fruit.unscoped to get a new Arel instance. There''d be nothing specific in this Arel instance about it being for `create`, i.e. `insert` in SQL. At this point you could jump over to Arel and build a new InsertManager instance I suppose: https://github.com/rails/arel/blob/master/lib/arel/crud.rb#L41 => https://github.com/rails/arel/blob/master/lib/arel/insert_manager.rb Of course, at this point, the discussion would no longer be within the scope of rails-core, assuming no one has interest in putting this into Rails core. -- Steve Schwartz On Sunday, January 13, 2013 at 10:02 AM, Steve Jorgensen wrote:> Could that be done as a plugin and not rely on undocumented internal APIs that are likely to change without warning? > > On Sunday, January 13, 2013 12:02:31 AM UTC-8, Nicolás Sanguinetti wrote: > > I think this is way too specific for core. Looks like a great idea for a plugin, though :) > > > > Cheers, > > -foca > > > > On 12/01/2013, at 21:57, Steve Jorgensen <ste...@stevej.name (javascript:)> wrote: > > > > > The use case would be using AR semantics to define an action, but then using that in a larger context, such as concatenating the SQL for several updates together using ";" and executing them in a single round-trip to the server. Technically, this just means just needing the SQL, but it seems silly to provide the SQL rather than the Arel from which the SQL can be trivially retrieved. > > > > > > On Saturday, January 12, 2013 7:47:18 PM UTC-8, Ryan Bigg wrote: > > > > What would the usecase for this be? > > > > > > > > > > > > > > > > On 13/01/2013, at 10:46, Steve Jorgensen <ste...@stevej.name> wrote: > > > > > > > > > There are times when it would be very useful to be able to get the Arel for any given ActiveRecord action such as a creation or update without actually carrying out the action. > > > > > > > > > > I''m imagine something like... > > > > > > > > > > the_arel = Fruit.arel{|f| > > > > > f.create :name => ''Banana'', :color => ''Yellow'' > > > > > } > > > > > > > > > > Does anyone else think this would be nice to have (or know of a way to do it already)? > > > > > -- > > > > > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. > > > > > To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. > > > > > To post to this group, send email to rubyonra...@googlegroups.com. > > > > > To unsubscribe from this group, send email to rubyonrails-co...@googlegroups.com. > > > > > For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en. > > > -- > > > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. > > > To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/yWAe7JMZ24QJ. > > > To post to this group, send email to rubyonra...@googlegroups.com (javascript:). > > > To unsubscribe from this group, send email to rubyonrails-co...@googlegroups.com (javascript:). > > > For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en. > -- > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. > To view this discussion on the web visit https://groups.google.com/d/msg/rubyonrails-core/-/guvPfxo1VM0J. > To post to this group, send email to rubyonrails-core@googlegroups.com (mailto:rubyonrails-core@googlegroups.com). > To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com (mailto:rubyonrails-core+unsubscribe@googlegroups.com). > For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To post to this group, send email to rubyonrails-core@googlegroups.com. To unsubscribe from this group, send email to rubyonrails-core+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-core?hl=en.
OK -- that''s an avenue for further research. My suggestion is starting to seem like less of a good idea the more I think about it, however. Perhaps, what''s really needed is simply more & better Arel documentation and usage examples (without sticking in lots of literal SQL bits that''ll break when table aliasing occurs). If it were easier to figure out how to do things directly in Arel, there would be little reason to use AR semantics to build Arel. I''m sure I don''t need any Rails Core group consensus to start working on more useful Arel docs. <g> On Sunday, January 13, 2013 7:53:33 AM UTC-8, JangoSteve wrote:> > What would the usecase for this be? > > I just had a similar need the other day, where I needed to build a > separate query based on the current scope (not clone the current scope, but > take the specific parameters of the scope to apply to another query which > wasn''t a scope at all). The way I had to do what I needed was to grab the > current scope and manually inspect the `where_values`, `joins_values`, etc. > > I think this is way too specific for core. Looks like a great idea for a > plugin, though :) > > I don''t disagree that this may be too specific for core. Just > demonstrating that I think there''s a need, so might make a good gem. > > Could that be done as a plugin and not rely on undocumented internal APIs > that are likely to change without warning? > > I would think so. Looking at the AR code for creating a record, > > https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb#L32 > > you can trace the actual save down to this line: > > https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb#L436 > > and if you look at the line above it, you get an array of Arel::Attributes > values from this method: > > https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_methods.rb#L323 > > which is just doing this (and note this method is protected, not private): > > attrs = {} > arel_table = self.class.arel_table > > attribute_names.each do |name| > attrs[arel_table[name]] = typecasted_attribute_value(name) > end > attrs > > > If you just want the array of attributes, then you could do the above and > combine it with Fruit.unscoped to get a new Arel instance. There''d be > nothing specific in this Arel instance about it being for `create`, i.e. > `insert` in SQL. At this point you could jump over to Arel and build a new > InsertManager instance I suppose: > https://github.com/rails/arel/blob/master/lib/arel/crud.rb#L41 => > https://github.com/rails/arel/blob/master/lib/arel/insert_manager.rb > > Of course, at this point, the discussion would no longer be within the > scope of rails-core, assuming no one has interest in putting this into > Rails core. > > -- Steve Schwartz > > On Sunday, January 13, 2013 at 10:02 AM, Steve Jorgensen wrote: > > Could that be done as a plugin and not rely on undocumented internal APIs > that are likely to change without warning? > > On Sunday, January 13, 2013 12:02:31 AM UTC-8, Nicolás Sanguinetti wrote: > > I think this is way too specific for core. Looks like a great idea for a > plugin, though :) > > Cheers, > -foca > > On 12/01/2013, at 21:57, Steve Jorgensen <ste...@stevej.name> wrote: > > The use case would be using AR semantics to define an action, but then > using that in a larger context, such as concatenating the SQL for several > updates together using ";" and executing them in a single round-trip to the > server. Technically, this just means just needing the SQL, but it seems > silly to provide the SQL rather than the Arel from which the SQL can be > trivially retrieved. > > On Saturday, January 12, 2013 7:47:18 PM UTC-8, Ryan Bigg wrote: > > What would the usecase for this be? > > > > On 13/01/2013, at 10:46, Steve Jorgensen <ste...@stevej.name> wrote: > > There are times when it would be very useful to be able to get the Arel > for any given ActiveRecord action such as a creation or update without > actually carrying out the action. > > I''m imagine something like... > > the_arel = Fruit.arel{|f| > f.create :name => ''Banana'', :color => ''Yellow'' > } > > Does anyone else think this would be nice to have (or know of a way to do > it already)? > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/rubyonrails-core/-/F7FN82ncfpgJ. > To post to this group, send email to rubyonra...@googlegroups.com. > To unsubscribe from this group, send email to > rubyonrails-co...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rubyonrails-core?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/rubyonrails-core/-/yWAe7JMZ24QJ. > To post to this group, send email to rubyonra...@googlegroups.com. > To unsubscribe from this group, send email to > rubyonrails-co...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/rubyonrails-core?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Ruby on Rails: Core" group. > To view this discussion on the web visit > https://groups.google.com/d/msg/rubyonrails-core/-/guvPfxo1VM0J. > To post to this group, send email to rubyonra...@googlegroups.com<javascript:> > . > To unsubscribe from this group, send email to > rubyonrails-co...@googlegroups.com <javascript:>. > For more options, visit this group at > http://groups.google.com/group/rubyonrails-core?hl=en. > > >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. 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