MongoDb $where not accepting javascript function

Question

In the MongoDb (v4.0) docs it says we can pass a javascript function to a where clause. I would expect the following trivial example to return zero docs...

let receipts = 
    await db
        .collection<IReceipt>("receipt_txs")
        .find({$where: function () { return false; } } )
        .toArray();

However this returns every doc.

The following syntax works, but for operational reasons i would rather use the above syntax.

let receipts = 
    await db
        .collection<IReceipt>("receipt_txs")
        .find({$where: "function () { return false; }" } )
        .toArray();

let receipts = 
    await db
        .collection<IReceipt>("receipt_txs")
        .find({$where: "false" } )
        .toArray();

Can anyone help me to understand where I'm going wrong? The docs are quite clear, and this syntax has been valid since v2 so I'm sure it can't be a bug.

Which language you are using? The first snippet will work only in javascript/mongo shell — Alex Blex
– Alex Blex, Commented Aug 30, 2018 at 16:21
I'm using typescript, hadnt considered the implications of the compile down, will check that now :/ — gingerbreadboy
– gingerbreadboy, Commented Aug 30, 2018 at 16:23

Akrion · Accepted Answer · 2018-08-30 16:31:08Z

1

$where with function literals is not compatible with all frameworks. For example it is a feature request in Meteor and not supported out of the box.

answered Aug 30, 2018 at 16:31

Akrion

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1 Comment

gingerbreadboy Over a year ago

Ok, I see now. Pass a function in directly is only supported by the mongo shell. Thanks.

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