What's the difference between “left_joins” and “includes” in Rails 5?
In Rails 5, they have added the ActiveRecord query method left_joins. What's the difference between left_joins and includes? I've always seen includes as a left join.
ruby-on-rails activerecord ruby-on-rails-5
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
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In Rails 5, they have added the ActiveRecord query method left_joins. What's the difference between left_joins and includes? I've always seen includes as a left join.
ruby-on-rails activerecord ruby-on-rails-5
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
add a comment |
In Rails 5, they have added the ActiveRecord query method left_joins. What's the difference between left_joins and includes? I've always seen includes as a left join.
ruby-on-rails activerecord ruby-on-rails-5
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
In Rails 5, they have added the ActiveRecord query method left_joins. What's the difference between left_joins and includes? I've always seen includes as a left join.
ruby-on-rails activerecord ruby-on-rails-5
ruby-on-rails activerecord ruby-on-rails-5
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
asked Nov 21 '18 at 15:00
daveomcddaveomcd
2,8971066106
2,8971066106
add a comment |
add a comment |
1 Answer
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includes by default loads the association data in 2 queries just like preload.
But with additional references call it switches from using two separate queries to creating a single LEFT OUTER JOIN like left_joins.
Refs:
Preload, Eagerload, Includes and Joins
Making sense of ActiveRecord joins, includes, preload, and eager_load
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
Includes will also defer to.eager_loadand load the records in one query if you apply a where clause.
– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables viaincludesinwhereclause by default. You need to specify them inreferencesfirst
– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can doFoo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.
– max
Nov 21 '18 at 16:23
@max yeah but if you change your example toFoo.includes(:bars).where("bars.baz = 'woo'")it will throw an error. Check outconditionspart inincludesdocs
– Martin Zinovsky
Nov 21 '18 at 16:28
1
@max But I didnt know thathashnotation works withoutreferencescall so thank you
– Martin Zinovsky
Nov 21 '18 at 16:32
add a comment |
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1 Answer
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1 Answer
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includes by default loads the association data in 2 queries just like preload.
But with additional references call it switches from using two separate queries to creating a single LEFT OUTER JOIN like left_joins.
Refs:
Preload, Eagerload, Includes and Joins
Making sense of ActiveRecord joins, includes, preload, and eager_load
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
Includes will also defer to.eager_loadand load the records in one query if you apply a where clause.
– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables viaincludesinwhereclause by default. You need to specify them inreferencesfirst
– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can doFoo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.
– max
Nov 21 '18 at 16:23
@max yeah but if you change your example toFoo.includes(:bars).where("bars.baz = 'woo'")it will throw an error. Check outconditionspart inincludesdocs
– Martin Zinovsky
Nov 21 '18 at 16:28
1
@max But I didnt know thathashnotation works withoutreferencescall so thank you
– Martin Zinovsky
Nov 21 '18 at 16:32
add a comment |
includes by default loads the association data in 2 queries just like preload.
But with additional references call it switches from using two separate queries to creating a single LEFT OUTER JOIN like left_joins.
Refs:
Preload, Eagerload, Includes and Joins
Making sense of ActiveRecord joins, includes, preload, and eager_load
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
Includes will also defer to.eager_loadand load the records in one query if you apply a where clause.
– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables viaincludesinwhereclause by default. You need to specify them inreferencesfirst
– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can doFoo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.
– max
Nov 21 '18 at 16:23
@max yeah but if you change your example toFoo.includes(:bars).where("bars.baz = 'woo'")it will throw an error. Check outconditionspart inincludesdocs
– Martin Zinovsky
Nov 21 '18 at 16:28
1
@max But I didnt know thathashnotation works withoutreferencescall so thank you
– Martin Zinovsky
Nov 21 '18 at 16:32
add a comment |
includes by default loads the association data in 2 queries just like preload.
But with additional references call it switches from using two separate queries to creating a single LEFT OUTER JOIN like left_joins.
Refs:
Preload, Eagerload, Includes and Joins
Making sense of ActiveRecord joins, includes, preload, and eager_load
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
includes by default loads the association data in 2 queries just like preload.
But with additional references call it switches from using two separate queries to creating a single LEFT OUTER JOIN like left_joins.
Refs:
Preload, Eagerload, Includes and Joins
Making sense of ActiveRecord joins, includes, preload, and eager_load
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
answered Nov 21 '18 at 15:14
Martin ZinovskyMartin Zinovsky
1,5041816
1,5041816
Includes will also defer to.eager_loadand load the records in one query if you apply a where clause.
– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables viaincludesinwhereclause by default. You need to specify them inreferencesfirst
– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can doFoo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.
– max
Nov 21 '18 at 16:23
@max yeah but if you change your example toFoo.includes(:bars).where("bars.baz = 'woo'")it will throw an error. Check outconditionspart inincludesdocs
– Martin Zinovsky
Nov 21 '18 at 16:28
1
@max But I didnt know thathashnotation works withoutreferencescall so thank you
– Martin Zinovsky
Nov 21 '18 at 16:32
add a comment |
Includes will also defer to.eager_loadand load the records in one query if you apply a where clause.
– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables viaincludesinwhereclause by default. You need to specify them inreferencesfirst
– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can doFoo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.
– max
Nov 21 '18 at 16:23
@max yeah but if you change your example toFoo.includes(:bars).where("bars.baz = 'woo'")it will throw an error. Check outconditionspart inincludesdocs
– Martin Zinovsky
Nov 21 '18 at 16:28
1
@max But I didnt know thathashnotation works withoutreferencescall so thank you
– Martin Zinovsky
Nov 21 '18 at 16:32
Includes will also defer to
.eager_load and load the records in one query if you apply a where clause.– max
Nov 21 '18 at 16:19
Includes will also defer to
.eager_load and load the records in one query if you apply a where clause.– max
Nov 21 '18 at 16:19
@max But you cant use eager loaded tables via
includes in where clause by default. You need to specify them in references first– Martin Zinovsky
Nov 21 '18 at 16:21
@max But you cant use eager loaded tables via
includes in where clause by default. You need to specify them in references first– Martin Zinovsky
Nov 21 '18 at 16:21
I''m not sure what you mean but you can do
Foo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.– max
Nov 21 '18 at 16:23
I''m not sure what you mean but you can do
Foo.includes(:bars).where(bars: { baz: 'woo' }). The result is the same as if you used eager_load.– max
Nov 21 '18 at 16:23
@max yeah but if you change your example to
Foo.includes(:bars).where("bars.baz = 'woo'") it will throw an error. Check out conditions part in includes docs– Martin Zinovsky
Nov 21 '18 at 16:28
@max yeah but if you change your example to
Foo.includes(:bars).where("bars.baz = 'woo'") it will throw an error. Check out conditions part in includes docs– Martin Zinovsky
Nov 21 '18 at 16:28
1
1
@max But I didnt know that
hash notation works without references call so thank you– Martin Zinovsky
Nov 21 '18 at 16:32
@max But I didnt know that
hash notation works without references call so thank you– Martin Zinovsky
Nov 21 '18 at 16:32
add a comment |
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