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Added #or to ActiveRecord::Relation #9052

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@gaelmuller
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@gaelmuller gaelmuller commented Jan 23, 2013

ActiveRecord::Relation#or returns a new relation, which is the
result of filtering the current relation according to the
conditions in the arguments, joining WHERE clauses with OR
operand, contraty to the default behaviour that uses AND.

ActiveRecord::Relation#or accepts conditions in one of several
formats. In the examples below, the resulting SQL is given as an
illustration; the actual query generated may be different depending
on the database adapter.

  • without arguments

If ActiveRecord::Relation#or is used without arguments, it returns
an ActiveRecord::OrChain object that can be used to chain queries
with any other relation method, like where:

Post.where("id = 1").or.where("id = 2")
> SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))

It can also be chained with a named scope:

Post.where("id = 1").or.containing_the_letter_a
> SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'body LIKE \\'%a%\\''))
  • ActiveRecord::Relation

When #or is used with an ActiveRecord::Relation as an argument, it
merges the two relations, with the exception of the WHERE clauses,
that are joined using the OR operand.

Post.where("id = 1").or(Post.where("id = 2"))
> SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))
  • anything you would pass to #where

ActiveRecord::Relation#or also accepts anything that could be passed
to the #where method, as a shortcut:

Post.where("id = 1").or("id = ?", 2)
> SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))

This is my first contribution to rails and I tried to keep things coherent with the current code, but I am obviously open for feedback.

@mdespuits
mdespuits reviewed Jan 24, 2013
View changes
activerecord/lib/active_record/relation/query_methods.rb Outdated
@@ -452,6 +468,60 @@ def where!(opts = :chain, *rest) # :nodoc:
end
end

# Returns a new relation, which is the result of filtering the current relation
# according to the conditions in the arguments, joining WHERE clauses with OR
# operand, contraty to the default behaviour that uses AND.

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@mdespuits
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@mdespuits mdespuits commented Jan 24, 2013

👍 Would love to see this one added. Simple idea that has been missing for a long time just like not.

@mdespuits
mdespuits reviewed Jan 24, 2013
View changes
activerecord/lib/active_record/relation/query_methods.rb Outdated
def method_missing(method, *args, &block)
right_relation = @scope.klass.unscoped {
@scope.klass.send(method, *args, &block)
}

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@mdespuits

mdespuits Jan 24, 2013

Generally multi-line blocks use the do..end style.

@gaelmuller
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@gaelmuller gaelmuller commented Jan 24, 2013

Thank you @mattdbridges for your feedback. I updated the commit with corrections for the typo and the multiline block.

@rafaelfranca
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@rafaelfranca rafaelfranca commented Jan 24, 2013

Sorry but some time ago we reached the conclusion to not add this method.

Some reason:

  1. It opens the door for wanting to expand this line of DSL further (including undesireable ventures into greater_or_equal_than).
  2. It's being a fairly uncommon query not in need of optimization.
  3. OR is usually a query smell

Thank you so much.

@gaelmuller
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@gaelmuller gaelmuller commented Mar 13, 2013

@rafaelfranca, I feel like the arguments to not add this method are those used for the like method that was rollbacked, but I think it doesn't apply here.

  1. This seems like a common need. You only have to look at this issue (#5545), or the several forums/stack overflow posts to realize that.
  2. This actually is not just an optimization, but a missing feature. With like or greater_or_equal_than, you can always easily write a where clause that would do the exact same thing. I don't see any way to join two scopes with a "OR" without rewriting the whole query in sql (which defeats the purpose of ActiveRecord).

If you still disagree, I will try to extract it as a plugin.

@gaelmuller
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@gaelmuller gaelmuller commented Mar 15, 2013

@tenderlove, @steveklabnik, you commented on a similar pull request (#6817). What is your opinion about this ?

@rafaelfranca
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@rafaelfranca rafaelfranca commented Mar 15, 2013

I don't have strong opinions about this one, so I think we can reopen to discuss.

@jeremy thoughts?

@rafaelfranca rafaelfranca reopened this Mar 15, 2013
@housekeeper
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@housekeeper housekeeper commented Mar 27, 2013

I would +1 this too but for a true scoping issue...

Developing a re-occurring calendaring gem and it would be awesome to chain scopes in the following ways

Calendar::Event.for_current_user.today
Calendar::Event.for_current_user.this_week
Calendar::Event.for_current_user.next_week

there are 3 scoped chains for 3 tables... an events table based on whether the user created the event or whether the user has been assigned/notified to/of the event in an event_users table. This is handled with no problem, my issue is when there is a re-occurring event which falls between a reoccurring start and end as well as an event start and end of which I need to OR - this is perfectly valid reason for this request and I believe a missing feature especially when wanting to create complex but efficient queries

FYI
An event only has one entry in the table
if this event re-occurs, its reoccurrence type is stored and the start/stop datetimes NOT each reoccurrence as an event.

@gregmolnar
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@gregmolnar gregmolnar commented Mar 27, 2013

👍 for this feature

@midu
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@midu midu commented Mar 27, 2013

👍 ❤️

@crmaxx
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@crmaxx crmaxx commented Apr 9, 2013

👍 for this feature

@ilyakatz
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@ilyakatz ilyakatz commented Apr 9, 2013

+1

1 similar comment
@KevinBongart
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@KevinBongart KevinBongart commented Apr 9, 2013

👍

@niuage
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@niuage niuage commented Apr 9, 2013

👍 💛

ActiveRecord::Relation#or returns a new relation, which is the
result of filtering the current relation according to the
conditions in the arguments, joining WHERE clauses with OR
operand, contraty to the default behaviour that uses AND.

ActiveRecord::Relation#or accepts conditions in one of several
formats. In the examples below, the resulting SQL is given as an
illustration; the actual query generated may be different depending
on the database adapter.

* without arguments

If ActiveRecord::Relation#or is used without arguments, it returns
an ActiveRecord::OrChain object that can be used to chain queries
with any other relation method, like where:

    Post.where("id = 1").or.where("id = 2")
    > SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))

It can also be chained with a named scope:

    Post.where("id = 1").or.containing_the_letter_a
    > SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'body LIKE \\'%a%\\''))

* ActiveRecord::Relation

When #or is used with an ActiveRecord::Relation as an argument, it
merges the two relations, with the exception of the WHERE clauses,
that are joined using the OR operand.

    Post.where("id = 1").or(Post.where("id = 2"))
    > SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))

* anything you would pass to #where

ActiveRecord::Relation#or also accepts anything that could be passed
to the #where method, as a shortcut:

    Post.where("id = 1").or("id = ?", 2)
    > SELECT `posts`.* FROM `posts`  WHERE (('id = 1' OR 'id = 2'))
@ghalley
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@ghalley ghalley commented Apr 25, 2013

+1

@descentintomael
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@descentintomael descentintomael commented Apr 25, 2013

+1 for this feature. I need some way to merge scopes together without having to do it manually column-by-column in squeel.

@atestu
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@atestu atestu commented Apr 25, 2013

👍

1 similar comment
@jcapron
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@jcapron jcapron commented Apr 25, 2013

👍

@christhekeele
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@christhekeele christhekeele commented Apr 25, 2013

+1
This would clean up those corners of my code where I feel like I'm not using an ORM anymore.

@williscool
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@williscool williscool commented Apr 26, 2013

In my humble opinion, leaving this to arel is a much more elegant

ie

user_arel_table = User.arel_table
User.where(user_arel_table[:name].eq('bob').or(user_arel_table[:age].lt(25))).to_sql

translates to

SELECT "users".* FROM "users"  WHERE (("users"."name" = 'bob' OR "users"."age" < 25))

or to convert one of your examples from the pull request

Post.where("id = 1").or(Post.where("id = 2"))

posts = Post.arel_table
Post.where(posts[:id].eq(1).or(posts[:id].eq(2))).to_sql
SELECT "posts".* FROM "posts"  WHERE (("posts"."id" = 1 OR "posts"."id" = 2))

you can also check out a couple other good examples here (only the upvoted ones of course)

http://stackoverflow.com/questions/7976358/activerecord-arel-or-condition

you can also join in other model/tables and then use their arel tables also. I can add some examples like that if anyone wants to see.

@laskaridis
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@laskaridis laskaridis commented Apr 26, 2013

It's embarrassing enough that this feature is NOT in ActiveRecord yet. +1

@descentintomael
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@descentintomael descentintomael commented Apr 26, 2013

@williscool That example works for small queries, but what if I have a large number of columns to search across? When I try the inject methods in the SO example I end up with Hash objects instead of ARel objects which don't work. I would prefer to have a native solution to combining scopes with OR. Rails is really good about having elegant solutions to many things, but this doesn't seem to be one of them.

@williscool
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@williscool williscool commented Apr 26, 2013

@descentintomael can you give an example with a large number of columns where the arel version is cumbersome?

And you would do your method chaining in between the where functions on the ActiveRecord::Relation objects. Not in the middle of them on the arel ones.

Man the naming of those things is quite confusing I wish they had completely different names.

What I mean is

User.containing_the_letter_a.where(admins.or(authors))

not

User.where(admins.or(authors).containing_the_letter_a)
@descentintomael
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@descentintomael descentintomael commented Apr 26, 2013

Right now I'm trying to search through my Order model which has quite a few columns. For instance, it has an amount and a currency column, those two need to be joined with 'AND' but then there are other columns like customer ID and PO number that come into play and need to be combined with 'OR'.

I'm not really sure yet how the syntax would go (without using Squeel), but I do like the direction taken in the first example:

Post.where("id = 1").or(Post.where("id = 2"))
right = (ActiveRecord::Relation === opts) ? opts : klass.unscoped.where(opts, rest)

unless left.where_values.empty? || right.where_values.empty?
left.where_values = [left.where_ast.or(right.where_ast)]

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@schuetzm

schuetzm Apr 27, 2013
Contributor

There's a problem here: you are modifying the original relations. If you're lucky, this will fail with ActiveRecord::ImmutableRelation, but this only happens if the relations have already been loaded.

The fix is simple:

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 1e291e6..ced097c 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -607,6 +607,7 @@ module ActiveRecord
         right = (ActiveRecord::Relation === opts) ? opts : klass.unscoped.where(opts, rest)

         unless left.where_values.empty? || right.where_values.empty?
+          left, right = left.dup, right.dup
           left.where_values = [left.where_ast.or(right.where_ast)]
           right.where_values = []
         end
@gaelmuller
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@gaelmuller gaelmuller commented Apr 30, 2013

@schuetzm, thank you for your feedback. I updated the commit to avoid ImmutableRelation exceptions.

@ghost
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@ghost ghost commented Jan 17, 2014

awesome, thank you.

@br3nt
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@br3nt br3nt commented Apr 29, 2014

Here's another example that needs or: Gist: Advanced Search utilising scopes (problem with match on any).

The PatientSearch#results method should be able to select between matching any of the criteria (results.or(query)), or all of the criteria (results.where(query)).

To make this work in rails currently, all query methods in PatientSearch would need to return arel instead of a relation so that they can be ORed together. This has a flow on effect such that any scopes used would also need to be rewritten as methods that return arel. Basically, throw the ActiveRecord query dsl and all its conveniences out the window.

This wouldn't be an issue if or existed.

  queries.each do |query|
    next if !query # skip if no query
    if match_criteria == 'all'
      results = results.where(query)  # each search gets ANDed
    elsif match_criteria == 'any'
      results = results.or(query)  # each search gets ORed
    end
  end
@midu
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@midu midu commented Apr 29, 2014

The problem is more that all these chainable methods are an incitation to violating the law of demeter, which we all know is wrong.

@vlad-shatskyi
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@vlad-shatskyi vlad-shatskyi commented Apr 29, 2014

@midu I would say that the law of demeter isn't an issue here. You can think of it as the builder pattern: we don't rely on object's internals, or dependencies of dependency, if you wish; instead we add pieces to one object. The returning object is always the same. In alternative syntax it could look like

query = Query.new
query.add_where_clause!(...)
query.add_where_clause!(...)
@br3nt
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@br3nt br3nt commented Apr 30, 2014

@midu, the example I provided is not an 'incitation to violating the law of demeter'. In fact it should quite cleanly build a query if there was an or operator.

The example I provided is a very legitimate example of where or requires support from ActiveRecord.

Besides, so long as its implementation is consistent with the rest of the dsl it should be the programmers prerogative to decide how they build queries.

@br3nt
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@br3nt br3nt commented Apr 30, 2014

@midu, the law of demeter (and all other concerns) is secondary to a much larger issue.

Here is why an 'or` operator should be supported by the ActiveRecord query dsl:

  • and and or are the core building blocks of mathematical logic and set theory
  • The SQL grammar is based on set theory and mathematical logic theory
  • SQL builds up a logic statement that defines the set to be returned
  • Excluding the 'or' operator from ActiveRecord's query dsl is denying the use of a foundational logic operator

This fact should be considered above all else as it is at the heart of SQL and all the mathematical theory that it is built around.

(on a side note, imagine if ruby didn't have an || operator)

@tarmotalu
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@tarmotalu tarmotalu commented May 5, 2014

+1

1 similar comment
@paxer
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@paxer paxer commented May 9, 2014

+1

@ghost
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@ghost ghost commented May 9, 2014

sounds good to me, but i have no interest in rails/AR.

@ghost
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@ghost ghost commented May 9, 2014

all the +1's are also strange. you would swear someone was using a bot-net to sway public opinion.

@ghost
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@ghost ghost commented May 9, 2014

"law of demeter", oh get on that, +1 +1 +1 +1.

@matthewd matthewd self-assigned this May 9, 2014
@dmgarland
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@dmgarland dmgarland commented May 13, 2014

+1

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@zavan
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@zavan zavan commented May 29, 2014

+1

@fuyi
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@fuyi fuyi commented May 30, 2014

would like to see this feature be added

@Sporky023
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@Sporky023 Sporky023 commented Jun 12, 2014

@br3nt said it right: OR is a fundamental mathematical operation which deserves support. Without using OR, our actions are limited.

@rails rails locked and limited conversation to collaborators Jun 13, 2014
@rafaelfranca
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@rafaelfranca rafaelfranca commented Jun 13, 2014

I locked the conversation. We already have enough reasons to thinks about it so we don't need more support comments like "+1" or "I agree with this". We are going to review and if we decide to merge we will reopen the discussion.

@rafaelfranca rafaelfranca modified the milestones: 4.2.0, 5.0.0 Aug 18, 2014
@sgrif
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@sgrif sgrif commented Jan 28, 2015

Closing in favor of #18706 or #16052

@sgrif sgrif closed this Jan 28, 2015
@rafaelfranca rafaelfranca modified the milestones: 5.0.0 [temp], 5.0.0 Dec 30, 2015
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