CODEWITHSUNDEEP
keymongodb
Mike Neumegen
Mike Neumegen

Reputation: 2486

MongoDB - Multiple $or operations

How would I have multiple $or operations? So far I've tried the following but it silently ignores the 2nd $or. 

{
  $or: [{a: 2}, {a: 3}], 
  $or: [{b: 5}, {b: 4}]
}

I assume this is because I'm using two identical keys. Is there any way around this?

Upvotes: 92

Views: 36697

Answers (4)

phoenixstudio
phoenixstudio

Reputation: 2598

Javascript Object can not have two properties with the same name (You have two $or in your case), and this will happen also with every query that does not respect this rule (only one property will be taken in consideration).

// try this Javascript code 
// (this will throw an error in some programming languages)
const x = { a: 1, a : 2 };
console.log("x:", x);
// this will output x: {a: 2} // <= the "a: 1" was gone.

(Nader) answer should fix your problem, You can also convert your query into one $or with all possible values, but it can get messy with more values/variables (Not recommended, but it can get rid of the two properties with same name issue).

// this will not work (your question) 
{
  $or: [{a: 2}, {a: 3}], 
  $or: [{b: 5}, {b: 4}]
}
// this will work (I recommend using $and in your use-case)
{
 $or: [
  {a: 2, b: 4}, 
  {a: 2, b: 5},
  {a: 3, b: 4}, 
  {a: 3, b: 5},
 ] 
}
// this is a better solution for your problem (Nader).
{
  $and: [
  { $or: [{a: 2}, {a: 3}] }, 
  { $or: [{b: 5}, {b: 4}] }
 ]
}
// If you are searching for a match where the value can 
//  have one of many possible values you can use $in 
{
  $or: [
  { a: { $in: [2, 3] } }, 
  { b: { $in: [4, 5] } }, 
  ]
}

Upvotes: 2

Gajender Singh
Gajender Singh

Reputation: 1313

For multiple like in sql we use $in and for not we use $nin vc is our collection name here.We are finding those string contains cpu or memo.

db.collection('vc').find({   "name" :   { $in: [ /cpu/, /memo/ ]   }     }

Upvotes: -3

user1231157
user1231157

Reputation: 43

$and will not do the job, since the 2nd $or will not validate if the first one fails.

From the Mongo man page:

The $and operator uses short-circuit evaluation. If the first expression (e.g. ) evaluates to false, MongoDB will not evaluate the remaining expressions.

Nested $or however should do the trick:

db.things.find({$or: [{$or : [{'a':1},{'b':2}]},{$or : [{'a':2},{'b':3}]}] })

Upvotes: -6

Nader
Nader

Reputation: 5595

Mongo 2.0 added an $and operator, so you can do a query like this:

db.things.find({$and: [{$or : [{'a':1},{'b':2}]},{$or : [{'a':2},{'b':3}]}] })

http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24and

Upvotes: 163

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