ReQL command: merge

Command syntax

singleSelection.merge([object | function, object | function, ...]) → object
object.merge([object | function, object | function, ...]) → object
sequence.merge([object | function, object | function, ...]) → stream
array.merge([object | function, object | function, ...]) → array

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(lambda 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(lambda 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)

Related commands

• pluck
• without
• map

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