Waterline createEach() modify the input array

[lucafaggianelli]

Node version: 10.16.3
Sails version (sails): 1.2.3
ORM hook version (sails-hook-orm): 2.1.1
Sockets hook version (sails-hook-sockets): 1.5.5
Organics hook version (sails-hook-organics): 1.0.0
Grunt hook version (sails-hook-grunt): 4.0.1
Uploads hook version (sails-hook-uploads): 0.4.3
DB adapter & version (e.g. sails-mysql@5.55.5): sails-mysql@1.0.1
Skipper adapter & version (e.g. skipper-s3@5.55.5): none

---

I don't know if it's the intended behavior, but for sure is very strange and not documented:

// I generate a large array with many entries
const arrayOfThings = [{}, {}, {}]

// I manipulate some entry and filter the array.
// The objects contained in the filtered array are the same of the original one,
// I didn't copy them.
const teamsToWrite = arrayOfThings.filter(x => x.league > 3)

await Team.createEach(teamsToWrite)

// later I use the original array, but the array entries present in teamsToWrite,
// have been modified with the created records
doOtherThings(arrayOfThings)

console.log(arrayOfThings.find(x => x.league > 3))
// { createdAt, updatedAt, id, ... }

Basically the input array has been modified by createEach. The docs say that the function doesn't return the created record but doesn't talk about preserving the array

[sailsbot]

@lucafaggianelli Thanks for posting! We'll take a look as soon as possible.

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---

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[whichking]

Hi, @lucafaggianelli!

This is expected behavior as of Sails v1, but I'm not seeing that it's explicitly stated outside of the upgrade guide. We'll have to make this aspect of createEach() more obvious in the docs.

Regarding your issue, we recommend either cloning an array before passing it into createEach() or rethinking your code in other ways to account for this behavior.

Thanks for bringing this to our attention!

[lucafaggianelli]

OK good to know! So just for clarification, the mutation of the argument happens on all CRUD methods, that is, create, set, delete? For example, I wouldn't need to do create(x).fetch() as x would be the newly created record?!??!

[whichking]

@lucafaggianelli—

It is true that criteria passed into any Waterline model method is now mutated, but it is also true that the default behavior of the methods create(), createEach(), update(), and destroy() is not to send back the created/updated/destroyed record(s). So you'll still need to use fetch() for those!

Here's the Waterline section of the upgrade guide that talks about this

Here's information pertaining specifically to the behavior of create(), createEach(), update(), and destroy()

[professor-rage]

Fascinating.

mongodb v3.6
sails-mongo v1.2
sailsjs v1.4

Mutated inputs from a create(input) and createEach(inputs) include the created record's ID(s), so technically a fetch() on createEach() isn't needed if you are only interested in grabbing the IDs.

I wouldn't recommend as I suspect this undocumented feature or bug, however you perceive it, may magically "go away" in a future release.