how to stop mongoose/javascript adding null values to arrays?

Question

I have a mongoose schema which has a field of comments: [String].

When I try to update the schema, I am checking if the value is null or empty by adding the following code into my controller,

if (req.body.comments !== null || req.body.comments !== '') { container.comments.push(req.body.comments) }

container.save() ...

However when I run this code (using postman for testing) and do not provide a value for the comment field, it updates in the database as null in the array.

comments: [String] is in the main schema definition and not part of a suc-document or anything like that.

Would anybody know a way round this issue or why this happens?

If you do not provide a value comments is undefined, not null. You should check for that case as well. — Gorka Hernandez
– Gorka Hernandez, Commented Oct 18, 2017 at 13:11

Gorka Hernandez · Accepted Answer · 2017-10-18 13:14:31Z

2

Make sure that comments is not undefined, you can handle all cases this way:

if (req.body.comments && req.body.comments !== '') {
  container.comments.push(req.body.comments)
}

That way empty strings, null and undefined values are not added, assuming req.body.comments always comes in as a string.

answered Oct 18, 2017 at 13:14

Gorka Hernandez

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1 Comment

Bud Over a year ago

Thanks a lot, your solution helped, it turns out that I had to use the && operator which you have used instead of the || operator which I was using

Rei Dien · Accepted Answer · 2017-10-19 00:36:33Z

0

You need to set container.comments as an empty array before you reach your condition statement

container.comments = container.comments || []
if (req.body.comments && req.body.comments !== '') {
  container.comments.push(req.body.comments)
}

this way the data saved on your database will always be an array, regardless of your sending comments on your request or not.

also its worth mentioning that saving an empty array on monggose will result to undefined unless you override it.

edited the example to take consideration if the array is not empty

edited Oct 19, 2017 at 0:36

answered Oct 18, 2017 at 13:16

Rei Dien

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1 Comment

Bud Over a year ago

your solution works but always creates an empty array, checking whether the array already exists before setting it to a new empty array is also workable in my case. thanks alot

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