How can I query for docs where the message property length is less than 100?

help
1

Hi,

I have a collection where documents have a message property,
How can I query for docs where the message property length is less than 100?
I can not make the following work:

{$where: "this.message.length < 100"}

Thanks

2

You might just need to return it?

YourCollection.find({
  $where: 'function() { return this.message.length < 100 }'
})
3

I get the following error:
Exception while invoking method ‘words.getByPage’ MongoError: TypeError: this.message is undefined :

4

If the error says that “this.message” is undefined for some documents, then you should just update the $where function to account for documents where this.message is undefined. (Sorry if that sounds snarky, but sometimes the straightforward explanation is the correct one!)

5

Yes, but this time it is the mongo version that does not support $where operator.
I wonder How meteor sets the mongodb version?
I ended adding a length property that is calculated at the moment of insert or update and using that new property on queries.

6

This is incorrect, Mongo has supported the $where operator since 2.2 (likely earlier, but the docs don’t go back that far anymore) and Meteor has bundled mongo 2.2 or above since launch in 2012.

I just tested with 1.8.1 and it works perfectly:

> test = new Mongo.collection('test')
> test.insert({message: 'abcdefghijklmnop'})
> test.find({$where: 'function(){ return this.message.length > 3}'}).fetch()
[ { _id: 'GcggX4tS8jT6CyB5Q', message: 'abcdefghijklmnop' } ]
> test.find({$where: 'function(){ return this.message.length < 3}'}).fetch()
[]

Meteor bundles the best supported version of Mongo with each version of Meteor.
Which is Mongo 4.0.6 for Meteor 1.8.1

What @menewman meant here is if this.message is sometimes undefined (thus throwing an error when trying to access length) just test for the existence of message:

YourCollection.find({
  $where: 'function() { return this.message && this.message.length < 100 }'
})
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