Command syntax

Description

Merge two or more objects together to construct a new object with properties from all. When there is a conflict between field names, preference is given to fields in the rightmost object in the argument list. merge also accepts a subquery function that returns an object, which will be used similarly to a map function.

Example: Equip Thor for battle.

r.table('marvel').get('thor').merge(
    r.table('equipment').get('hammer'),
    r.table('equipment').get('pimento_sandwich')
).run(conn)

Example: Equip every hero for battle, using a subquery function to retrieve their weapons.

r.table('marvel').merge{ |hero|
    { :weapons => r.table('weapons').get(hero['weapon_id']) }
}.run(conn)

Example: Use merge to join each blog post with its comments.

Note that the sequence being merged—in this example, the comments—must be coerced from a selection to an array. Without coerce_to the operation will throw an error (“Expected type DATUM but found SELECTION”).

r.table('posts').merge{ |post|
    { :comments => r.table('comments').get_all(post['id'],
        {:index => 'post_id'}).coerce_to('array') }
}.run(conn)

Example: Merge can be used recursively to modify object within objects.

r.expr({:weapons => {:spectacular_graviton_beam => {:dmg => 10, :cooldown => 20}}}).merge(
    {:weapons => {:spectacular_graviton_beam => {:dmg => 10}}}
).run(conn)

Example: To replace a nested object with another object you can use the literal keyword.

r.expr({:weapons => {:spectacular_graviton_beam => {:dmg => 10, :cooldown => 20}}}).merge(
    {:weapons => r.literal({:repulsor_rays => {:dmg => 3, :cooldown => 0}})}
).run(conn)

Example: Literal can be used to remove keys from an object as well.

r.expr({:weapons => {:spectacular_graviton_beam => {:dmg => 10, :cooldown => 20}}}).merge(
    {:weapons => {:spectacular_graviton_beam => r.literal()}}
).run(conn)