Mongo $ and selector

Question

How does $ mango and selector work? I am having trouble returning the correct results.

Let's say I have a collection of something like this:

{ "_id" : "F7mdaZC2eBQDXA5wx", "quantity" : 5 }
{ "_id" : "F7mdaZC2eBQDXA5wx", "quantity" : 9 }
{ "_id" : "F7mdaZC2eBQDXA5wx", "quantity" : 34 }
{ "_id" : "F7mdaZC2eBQDXA5wx", "quantity" : 66 }

and I run the query:

var selectorMin = 9;
var selectorMax = 42;

ScrapReport.find({ $and: [ { quantity: { $gte: selectorMin }, quantity: { $lte: selectorMax } } ] })

I expected the mongo to return only 9 and 34 to me. But for some reason it also returns 5 and 66.

What happened to my request?

Answer 1

, , quantity >= 9 .. 9, 34 66 , quantity <= 42 ie 34, 9 5. , , , ..

Documents which satisfy "quantity >= 9"
+
Documents which satisfy "quantity <= 42"

not

Documents which satisfy "9 <= quantity <= 42"

ScrapReport.find({ "quantity": { "$gte": selectorMin, "$lte": selectorMax } })

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9 <= quantity <= 42

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Answer 2

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{ $and: [ { quantity: { $gte: selectorMin }, quantity: { $lte: selectorMax } } ] }

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ScrapReport.find({ $and: [ { quantity: { $gte: selectorMin } }, { quantity: { $lte: selectorMax } } ] })

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ScrapReport.find({ quantity: 9 })

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ScrapReport.find({ quantity: 9, quantity: 5 })

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ScrapReport.find({ quantity: 9, quantity: 5, quantity: 34 })

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ScrapReport.find({ quantity: { $gte: selectorMin }, quantity: { $lte: selectorMax } })

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Answer 3

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ScrapReport.find( { "$and": [{ "quantity": { "$lte": selectorMax } } ] } )

:

ScrapReport.find( { "quantity": { "$lte": selectorMax } } )

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@chridam, :

ScrapReport.find({ "quantity": { "$gte": selectorMin, "$lte": selectorMax } })