Scoping FOR loop - to prevent duplicate INSERT

[Klaas van der Molen]

Hi,

The query below inserts the object {title: "c"} twice in collection_2.

However I want only one insert for the second collection.

The question is how to scope the FOR loop in this case? 

Brackets are not accepted.

LET array = [{title: "a"},{title: "b"}]
FOR item IN array
    INSERT item INTO collection_1
INSERT {title: "c"} INTO collection_2

Many thanks!

Klaas van der Molen

[Wilfried Gösgens]

Hi,

the only way AQL offers to break the scope is to use a sub-query, which will then be executed before the main query.

[Michael Hackstein]

Hi,

For this particular query there are actually two more possibilities:

LET array = [{title: "a"},{title: "b"}]
FOR item IN array
    INSERT item INTO collection_1
INSERT {title: "c"} INTO collection_2

Could run as:

INSERT {title: "c"} INTO collection_2

LET array = [{title: "a"},{title: "b"}]

FOR item IN array

    INSERT item INTO collection_1

This way the second INSERT statement is bore the Loop over array.

AQL is not whitespace sensitive for scopes

Which means your query is actually:

LET array = [{title: "a"},{title: "b"}]

FOR item IN array

    INSERT item INTO collection_1

    INSERT {title: "c"} INTO collection_2

The second insert is within the loop.

The other alternative to a subquery would be a COLLECT with constant condition:

LET array = [{title: "a"},{title: "b"}]

FOR item IN array

    INSERT item INTO collection_1

COLLECT x = 1 /* This groups all outputs of the former for loop. AS the grouping is done on a constant, we will end up with a single Group */

INSERT {title: "c"} INTO collection_2

Best

Michael

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[Simran Spiller]

Instead of grouping by a constant, you can also apply a LIMIT for the same effect:

LET array = [{title: "a"},{title: "b"}]

FOR item IN array

    INSERT item INTO collection_1

    LIMIT 1

    INSERT {title: "c"} INTO collection_2