Using $or and $ne Operators Together in MongoDB Query

I am trying to run a MongoDB query to return all documents that don't match one value OR another. After consulting the documentation, I see this example:

$or: [ quantity: $lt: 20 , price: 10 ]


So this is what I tried:

$or: [ paymentType: $ne: "full" , $ne: "partial" ]


This results in an error:

'unknown top level operator: $ne'

I also tried this:

$or: [ paymentType: $ne: "full" , paymentType: $ne: "partial" ]


... but this simply returns all documents, with no filtering done on the "paymentType" property.

What's the correct syntax here?

$nin

paymentType:$nin:["full", "partial"]

3 Answers
3

Your third version of code syntax is correct.

But the logic seems wrong.

Your query translated to:

paymentType != full or paymentType != partial


This actually always hold true, (since one paymentType value cannot be full and partial at the same time.)

paymentType

full

partial

Update

To clarify, what I'm trying to query -- in plain English -- is to return all results where "paymentType" is not "full" or "partial".

In this case you should use $and instead. or $nin is also good.

$and

$nin

Remember this law:

not (p or q) <=> (not p) and (not q)


$and

$nin

So, thanks to a commenter for pointing out that I could either use $nin or $and but not $or. Another option, which I find the most intuitive in this particular case, is the $nor operator, like so:

$nin

$and

$or

$nor

$nor: [ paymentType: $ne: "full" , paymentType: $ne: "partial" ]


This will return all documents that don't match either of these values.

If you need to find all documents which do not match those two values only why don't you simply change the $or to $and? Easiest and shortest is to use the $nin as already suggested but not sure why complicate it with $nor/$or etc.

all

$or

$and

$nin

$nor

$or

$and: [ paymentType: $ne: "full" , paymentType: $ne: "partial" ]


will select all documents that don't match either of these values. It reads and understands much easier then the double negation you end up with $nor no?

$nor

It says give me all paymentTypes which are not full and not partial. Same if you use the $nin.

full

partial

$nin

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