MongoDB Extended JSON (v1)

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.

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:

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

The following queries return an error:

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

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

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. mongosh stores a null value instead.

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

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

The resulting documents are different:

{ "name" : "Sally", "age" : null }
{ "name" : "Sally", "age" : undefined }

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:

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:

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:

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

Important

This insert behavior is different in 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.