Navigation

MongoDB Extended JSON (v1)

On this page

Important

Disambiguation

The following page discusses MongoDB Extended JSON v1 (Legacy extended JSON). For discussion on MongoDB Extended JSON v2, see MongoDB Extended JSON (v2).

For supported data types in mongo, see mongosh Data Types.

For supported data types in the legacy mongo shell, see Data Types in the Legacy mongo Shell.

JSON can only represent a subset of the types supported by BSON. To preserve type information, MongoDB adds the following extensions to the JSON format:

  • Strict mode. Strict mode representations of BSON types conform to the JSON RFC. Any JSON parser can parse these strict mode representations as key/value pairs; however, only the MongoDB internal JSON parser recognizes the type information conveyed by the format.
  • mongo Shell mode. The MongoDB internal JSON parser and the mongo shell can parse this mode.

The representation used for the various data types depends on the context in which the JSON is parsed.

MongoDB Extended JSON v1 and MongoDB Drivers

The following drivers use the Extended JSON v1.0 (Legacy)

  • C#
  • Ruby

For the other drivers, refer to MongoDB Extended JSON (v2).

Parsers and Supported Format

Input in Strict Mode

The following can parse representations in strict mode with recognition of the type information.

  • mongoimport version 4.0 and earlier
  • --query option of various MongoDB tools
  • MongoDB Compass

Other JSON parsers, including mongo shell, can parse strict mode representations as key/value pairs, but without recognition of the type information.

Input in mongo Shell Mode

The following can parse representations in mongo shell mode with recognition of the type information.

  • mongoimport version 4.0 and earlier
  • --query option of various MongoDB tools
  • mongo shell

Output in Strict mode

Before version 4.2, mongoexport outputs data in Strict mode of MongoDB Extended JSON v1.

Output in mongo Shell Mode

Before version 4.2, bsondump outputs in mongo Shell mode.

BSON Data Types and Associated Representations

The following presents the BSON data types and the associated representations in Strict mode and mongo Shell mode.

Binary

data_binary
Strict Mode mongo Shell Mode 
{ "$binary": "<bindata>", "$type": "<t>" }

BinData ( <t>, <bindata> )

Where the values are as follows:

  • <bindata> is the base64 representation of a binary string.
  • <t> is a representation of a single byte indicating the data type. In Strict mode it is a hexadecimal string, and in Shell mode it is an integer. See the extended bson documentation. http://bsonspec.org/spec.html

Date

data_date
Strict Mode mongo Shell Mode 
{ "$date": "<date>" }

new Date ( <date> )

In Strict mode, <date> is an ISO-8601 date format with a mandatory time zone field following the template YYYY-MM-DDTHH:mm:ss.mmm<+/-Offset>.

In Shell mode, <date> is the JSON representation of a 64-bit signed integer giving the number of milliseconds since epoch UTC.

Timestamp

data_timestamp
Strict Mode mongo Shell Mode 
{ "$timestamp": { "t": <t>, "i": <i> } }

Timestamp( <t>, <i> )

Where the values are as follows:

  • <t> is the JSON representation of a 32-bit unsigned integer for seconds since epoch.
  • <i> is a 32-bit unsigned integer for the increment.

Regular Expression

data_regex
Strict Mode mongo Shell Mode 
{ "$regex": "<sRegex>", "$options": "<sOptions>" }

/<jRegex>/<jOptions>

Where the values are as follows:

  • <sRegex> is a string of valid JSON characters.
  • <jRegex> is a string that may contain valid JSON characters and unescaped double quote (") characters, but may not contain unescaped forward slash (/) characters.
  • <sOptions> is a string containing the regex options represented by the letters of the alphabet.
  • <jOptions> is a string that may contain only the characters ‘g’, ‘i’, ‘m’ and ‘s’ (added in v1.9). Because the JavaScript and mongo Shell representations support a limited range of options, any nonconforming options will be dropped when converting to this representation.

OID

data_oid
Strict Mode mongo Shell Mode 
{ "$oid": "<id>" }

ObjectId( "<id>" )

Where the values are as follows:

  • <id> is a 24-character hexadecimal string.

DB Reference

data_ref
Strict Mode mongo Shell Mode 
{ "$ref": "<name>", "$id": "<id>" }

DBRef("<name>", "<id>")

Where the values are as follows:

  • <name> is a string of valid JSON characters.
  • <id> is any valid extended JSON type.

Undefined Type

data_undefined
Strict Mode mongo Shell Mode 
{ "$undefined": true }

undefined

The representation for the JavaScript/BSON undefined type.

You cannot use undefined in query documents. Consider the following document inserted into the people collection using the legacy mongo shell:

copy 
db.people.insertOne( { name : "Sally", age : undefined } )

The following queries return an error:

copy 
db.people.find( { age : undefined } )
db.people.find( { age : { $gte : undefined } } )

However, you can query for undefined values using $type, as in:

copy 
db.people.find( { age : { $type : 6 } } )

This query returns all documents for which the age field has value undefined.

Important

The undefined BSON type is deprecated. bin.mongosh stores a null value instead.

For example, use the same code to insert a document in bin.mongosh and in the legacy mongo shell:

copy 
db.people.insertOne( { name : "Sally", age : undefined } )

The resulting documents are different:

MinKey

data_minkey
Strict Mode mongo Shell Mode 
{ "$minKey": 1 }

MinKey

The representation of the MinKey BSON data type that compares lower than all other types. See Comparison/Sort Order for more information on comparison order for BSON types.

MaxKey

data_maxkey
Strict Mode mongo Shell Mode 
{ "$maxKey": 1 }

MaxKey

The representation of the MaxKey BSON data type that compares higher than all other types. See Comparison/Sort Order for more information on comparison order for BSON types.

NumberLong

data_numberlong
Strict Mode mongo Shell Mode 
{ "$numberLong": "<number>" }

NumberLong( "<number>" )

NumberLong is a 64 bit signed integer. In the legacy mongo shell, you must use quotation marks to insert a NumberLong or the operation will produce an error.

For example, the following commands attempt to insert 9223372036854775807 as a NumberLong with and without quotation marks around the integer value:

copy 
db.json.insertOne( { longQuoted : NumberLong("9223372036854775807") } )
db.json.insertOne( { longUnQuoted : NumberLong(9223372036854775807) } )

The highlighted line produces an error in the legacy mongo shell. The insert succeeds in mongosh.

NumberDecimal

data_numberdecimal
Strict Mode mongo Shell Mode 
{ "$numberDecimal": "<number>" }

NumberDecimal( "<number>" )

NumberDecimal is a high-precision decimal. You must include quotation marks, or the input number will be treated as a double, resulting in data loss.

For example, the following commands insert 123.40 as a NumberDecimal with and without quotation marks around the value:

copy 
db.json.insertOne( { decimalQuoted : NumberDecimal("123.40") } )
db.json.insertOne( { decimalUnQuoted : NumberDecimal(123.40) } )

When you retrieve the documents, the value of decimalUnQuoted has changed, while decimalQuoted retains its specified precision:

copy 
db.json.find()
{ "_id" : ObjectId("596f88b7b613bb04f80a1ea9"), "decimalQuoted" : NumberDecimal("123.40") }
{ "_id" : ObjectId("596f88c9b613bb04f80a1eaa"), "decimalUnQuoted" : NumberDecimal("123.400000000000") }

Important

This insert behavior is different in bin.mongosh.

The quoted string format, NumberDecimal("123.40"), is deprecated. The insert succeeds, but also produces a warning.

The unquoted string format, NumberDecimal(123.40), stores the value as 123.4. The trailing 0 is dropped.

© MongoDB, Inc 2008-present. MongoDB, Mongo, and the leaf logo are registered trademarks of MongoDB, Inc.