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$type

$type

$type selects documents where the value of the field is an instance of the specified BSON type(s). Querying by data type is useful when dealing with highly unstructured data where data types are not predictable.

You can use $type for deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

A $type expression for a single BSON type has the following syntax:

{ field: { $type: <BSON type> } }

You can specify either the number or alias for the BSON type.

The $type expression can also accept an array of BSON types and has the following syntax:

{ field: { $type: [ <BSON type1> , <BSON type2>, ... ] } }

The above query matches documents where the field value is any of the listed types. The types specified in the array can be either numeric or string aliases.

See Querying by Multiple Data Types for an example.

Available Types describes the BSON types and their corresponding numeric and string aliases.

Tip

See also:

$type returns documents where the BSON type of the field matches the BSON type passed to $type.

For documents where field is an array, $type returns documents in which at least one array element matches a type passed to $type.

Queries for $type: "array" return documents where the field itself is an array.

The $type operator accepts string aliases for the BSON types in addition to the numbers corresponding to the BSON types. [1]

Type
Number
Alias
Notes

Double

1

"double"

String

2

"string"

Object

3

"object"

Array

4

"array"

Binary data

5

"binData"

Undefined

6

"undefined"

Deprecated.

ObjectId

7

"objectId"

Boolean

8

"bool"

Date

9

"date"

Null

10

"null"

Regular Expression

11

"regex"

DBPointer

12

"dbPointer"

Deprecated.

JavaScript

13

"javascript"

Symbol

14

"symbol"

Deprecated.

32-bit integer

16

"int"

Timestamp

17

"timestamp"

64-bit integer

18

"long"

Decimal128

19

"decimal"

Min key

-1

"minKey"

Max key

127

"maxKey"

$type supports the number alias, which matches against the following BSON types:

For examples, see Examples.

[1] Users can no longer use the query filter $type: 0 as a synonym for $exists:false. To query for null or missing fields, see Query for Null or Missing Fields.

Tip

See also:

MinKey and MaxKey are used in comparison operations and exist primarily for internal use. For all possible BSON element values, MinKey is always the smallest value while MaxKey is always the greatest value.

Querying for minKey or maxKey with $type only returns fields that match the special MinKey or MaxKey values.

Suppose that the data collection has two documents with MinKey and MaxKey:

db.data.insertMany( [
{ _id : 1, x : { "$minKey" : 1 } },
{ _id : 2, y : { "$maxKey" : 1 } }
] )

The following query returns the document with _id: 1:

db.data.find( { x: { $type: "minKey" } } )

The following query returns the document with _id: 2:

db.data.find( { y: { $type: "maxKey" } } )

The addressBook contains addresses and zipcodes, where zipCode has string, int, double, and long values:

db.addressBook.insertMany( [
{ _id : 1, address : "2030 Martian Way", zipCode : "90698345" },
{ _id : 2, address : "156 Lunar Place", zipCode : 43339374 },
{ _id : 3, address : "2324 Pluto Place", zipCode : NumberLong(3921412) },
{ _id : 4, address : "55 Saturn Ring" , zipCode : NumberInt(88602117) },
{ _id : 5, address : "104 Venus Drive", zipCode : ["834847278", "1893289032"] }
] )

The following queries return all documents where zipCode is the BSON type string or is an array containing an element of the specified type:

db.addressBook.find( { zipCode : { $type : 2 } } );
db.addressBook.find( { zipCode : { $type : "string" } } );

These queries return:

{ _id : 1, address : "2030 Martian Way", zipCode : "90698345" }
{ _id : 5, address : "104 Venus Drive", zipCode : [ "834847278", "1893289032" ] }

The following queries return all documents where zipCode is the BSON type double or is an array containing an element of the specified type:

db.addressBook.find( { zipCode : { $type : 1 } } );
db.addressBook.find( { zipCode : { $type : "double" } } );

These queries return:

{ _id : 2, address : "156 Lunar Place", zipCode : 43339374 }

The following query uses the number alias to return documents where zipCode is the BSON type double, int, or long or is an array containing an element of the specified types:

db.addressBook.find( { zipCode : { $type : "number" } } )

These queries return:

{ _id : 2, address : "156 Lunar Place", zipCode : 43339374 }
{ _id : 3, address : "2324 Pluto Place", zipCode : NumberLong(3921412) }
{ _id : 4, address : "55 Saturn Ring", zipCode : 88602117 }

The grades collection contains names and averages, where classAverage has string, int, and double values:

db.grades.insertMany( [
{ _id : 1, name : "Alice King" , classAverage : 87.333333333333333 },
{ _id : 2, name : "Bob Jenkins", classAverage : "83.52" },
{ _id : 3, name : "Cathy Hart", classAverage: "94.06" },
{ _id : 4, name : "Drew Williams" , classAverage : NumberInt("93") }
] )

The following queries return all documents where classAverage is the BSON type string or double or is an array containing an element of the specified types. The first query uses numeric aliases while the second query uses string aliases.

db.grades.find( { classAverage : { $type : [ 2 , 1 ] } } );
db.grades.find( { classAverage : { $type : [ "string" , "double" ] } } );

These queries return the following documents:

{ _id : 1, name : "Alice King", classAverage : 87.33333333333333 }
{ _id : 2, name : "Bob Jenkins", classAverage : "83.52" }
{ _id : 3, name : "Cathy Hart", classAverage : "94.06" }

The restaurants collection uses minKey for any grade that is a failing grade:

db.restaurants.insertOne( [
{
_id: 1,
address: {
building: "230",
coord: [ -73.996089, 40.675018 ],
street: "Huntington St",
zipcode: "11231"
},
borough: "Brooklyn",
cuisine: "Bakery",
grades: [
{ date : new Date(1393804800000), grade : "C", score : 15 },
{ date : new Date(1378857600000), grade : "C", score : 16 },
{ date : new Date(1358985600000), grade : MinKey(), score : 30 },
{ date : new Date(1322006400000), grade : "C", score : 15 }
],
name : "Dirty Dan's Donuts",
restaurant_id : "30075445"
}
] )

And maxKey for any grade that is the highest passing grade:

db.restaurants.insertOne( [
{
_id : 2,
address : {
building : "1166",
coord : [ -73.955184, 40.738589 ],
street : "Manhattan Ave",
zipcode : "11222"
},
borough: "Brooklyn",
cuisine: "Bakery",
grades: [
{ date : new Date(1393804800000), grade : MaxKey(), score : 2 },
{ date : new Date(1378857600000), grade : "B", score : 6 },
{ date : new Date(1358985600000), grade : MaxKey(), score : 3 },
{ date : new Date(1322006400000), grade : "B", score : 5 }
],
name : "Dainty Daisey's Donuts",
restaurant_id : "30075449"
}
] )

The following query returns any restaurant whose grades.grade field contains minKey or is an array containing an element of the specified type:

db.restaurants.find(
{ "grades.grade" : { $type : "minKey" } }
)

This returns the following results:

{
_id : 1,
address : {
building : "230",
coord : [ -73.996089, 40.675018 ],
street : "Huntington St",
zipcode : "11231"
},
borough : "Brooklyn",
cuisine : "Bakery",
grades : [
{ date : ISODate("2014-03-03T00:00:00Z"), grade : "C", score : 15 },
{ date : ISODate("2013-09-11T00:00:00Z"), grade : "C", score : 16 },
{ date : ISODate("2013-01-24T00:00:00Z"), grade : { "$minKey" : 1 }, score : 30 },
{ date : ISODate("2011-11-23T00:00:00Z"), grade : "C", score : 15 }
],
name : "Dirty Dan's Donuts",
restaurant_id : "30075445"
}

The following query returns any restaurant whose grades.grade field contains maxKey or is an array containing an element of the specified type:

db.restaurants.find(
{ "grades.grade" : { $type : "maxKey" } }
)

This returns the following results:

{
_id : 2,
address : {
building : "1166",
coord : [ -73.955184, 40.738589 ],
street : "Manhattan Ave",
zipcode : "11222"
},
borough : "Brooklyn",
cuisine : "Bakery",
grades : [
{ date : ISODate("2014-03-03T00:00:00Z"), grade : { "$maxKey" : 1 }, score : 2 },
{ date : ISODate("2013-09-11T00:00:00Z"), grade : "B", score : 6 },
{ date : ISODate("2013-01-24T00:00:00Z"), grade : { "$maxKey" : 1 }, score : 3 },
{ date : ISODate("2011-11-23T00:00:00Z"), grade : "B", score : 5 }
],
name : "Dainty Daisey's Donuts",
restaurant_id : "30075449"
}

A collection named sensorReading contains the following documents:

db.sensorReading.insertMany( [
{ _id : 1, readings : [ 25, 23, [ "Warn: High Temp!", 55 ], [ "ERROR: SYSTEM SHUTDOWN!", 66 ] ] },
{ _id : 2, readings : [ 25, 25, 24, 23 ] },
{ _id : 3, readings : [ 22, 24, [] ] },
{ _id : 4, readings : [] },
{ _id : 5, readings : 24 }
] )

The following query returns any document in which the readings field is an array, empty or non-empty.

db.SensorReading.find( { readings : { $type: "array" } } )

The above query returns the following documents:

{
_id : 1,
readings : [
25,
23,
[ "Warn: High Temp!", 55 ],
[ "ERROR: SYSTEM SHUTDOWN!", 66 ]
]
},
{
_id : 2,
readings : [ 25, 25, 24, 23 ]
},
{
_id : 3,
readings : [ 22, 24, [] ]
},
{
_id : 4,
readings : []
}

In the documents with _id : 1, _id : 2, _id : 3, and _id : 4, the readings field is an array.