Problems with Mongo value-in-array query: $not operator doesn't work, and ObjectIds cannot be selected

Question

I am trying to select a document which does NOT contain a value in a document's array. I'm having two problems, which I'll present separately: (1) I cannot get the $not operator to work with a value-in-array query: For example, if I have the following document in my collection: ` { _id: ObjectId("000000000000000000000000"), mylist: [ "red", "green", "blue" ] } ` I can select this document using: ` db.myCol.find({mylist:"red"}) ` However, I would like to select this document by testing for the absence of orange: ` db.myCol.find({$not:{mylist:"orange"}}) ` Why does this not work? (2) I cannot get the value in array query to work if the array values are ObjectIds: ` { _id: Object("000000000000000000000000"), mylist: [ ObjectId("111111111111111111111111") ] } ` The following does NOT retrieve this document: ` myCol.find({mylist:ObjectId("111111111111111111111111")}) ` Can someone suggest what I might be doing wrong?

Accepted Answer

There is no `$not` that works like, you want `$ne` for simple cases like yours:

```
db.myCol.find({ mylist: { $ne: 'orange' } })
```

Your second should (and does) work fine for me, perhaps you're using the wrong number of ones.

Problems with Mongo value-in-array query: $not operator doesn't work, and ObjectIds cannot be selected

Solution

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