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bson

Bson library for Dart programming language

Version 5.0.0 has breaking API changes. See changelog for details.

Package

This package allows the conversion of a map of dart elements into a binary Bson representation and viceversa. The input can be a standard dart map with key name of the value and the value itself, or an ejson representation of the value or a mixed source. It is also possible to serialize objects that uses the BsonSerializable mixin.

There is a Codec class that allows to define which kind of serialization we want to perform (depending on the source) + three specialized classes that preset the parameters dependig on the source that we are providing. These classes (shortcuts for the Codec one) are:

  • BsonCodec
  • EjsonCodec
  • ObjectCode

BSON

This is the most important converter. It converts from a document of objects into the BSON format. The objects must be of a supported type. The actually managed objects are:

Dart Type Internal Type Bson Byte Returned internal Returned Dart Notes
double BsonDouble 1 / 0x01 BsonDouble double
String BsonString 2 / 0x02 BsonString String
Map BsonMap 3 / 0x03 BsonMap Map
DbRef BsonDbRef Map convention BsonDbRef DbRef Map containing keys "$id" and "$ref"
List BsonArray 4 / 0x04 BsonArray List
LegacyUuid BsonLegacyUuid 5 / 0x05 BsonLegacyUuid LegacyUuid Sub Type 3 / 0x03
UuidValue BsonUuid 5 / 0x05 BsonUuid UuidValue Sub Type 4 / 0x04
ObjectId BsonObjectId 7 / 0x07 BsonObjectId ObjectId
bool BsonBoolean 8 / 0x08 BsonBoolean bool
DateTime BsonDate 9 / 0x09 BsonDate DateTime
Null BsonNull 10 / 0x0A BsonNull Null
RegExp BsonRegexp 11 / 0x0B BsonRegexp RegExp
DBPointer DBPointer 12 / 0x0C DBPointer DBPointer @Deprecated
JsCode BsonCode 13 / 0x0D BsonCode JsCode
int BsonInt 16 / 0x10 BsonInt int when bitLength <= 31
Int32 BsonInt 16 / 0x10 BsonInt int
Timestamp BsonTimestamp 17 / 0x11 BsonTimestamp Timestamp
int BsonLong 18 / 0x12 BsonLong Int64 when bitLength > 31
Int64 BsonLong 18 / 0x12 BsonLong Int64
Decimal BsonDecimal128 19 / 0x13 BsonDecimal128 Decimal

The objects expected are those of the column "Dart Type", while the objects returned are those of the column "Returned Dart". The other types are intended to be used internally. The Bson Types are eventually accepted in input instead of the corresponding Dart types. Most of the types expected are from the Dart language itself, with these exceptions:

Class Package
DbRef Bson
LegacyUuid Bson
UuidValue Uuid
ObjectId Bson
DBPointer Bson
JsCode Bson
Timestamp Bson
Int32 Fixnum
Int64 Fixnum
Decimal Decimal

To serialize an bson map you have to use the serialize method of the BsonCodec class. Ex. var bsonBinary = BsonCodec.serialize(bsonDocument); You can see a serialization example here

To deserialize an bson map you have to use the deserialize method of the BsonCodec class. Ex. var result = BsonCodec.deserialize(bsonBinary); You can see a deserialization example here

EJSON

It converts from a document in format ejson into the BSON format. Only ejson version 2 is supported. The objects must be of a supported type. The actually managed objects are:

EJson Internal Type Bson Byte Returned internal Returned EJson Notes
"$numberDouble" BsonDouble 1 / 0x01 BsonDouble "$numberDouble"
String BsonString 2 / 0x02 BsonString String
Map BsonMap 3 / 0x03 BsonMap Map
"$ref" - "$id" BsonDbRef Map convention BsonDbRef "$ref" - "$id" Map containing keys "$id" and "$ref"
List BsonArray 4 / 0x04 BsonArray List
"$binary" BsonBinary 5 / 0x05 BsonBinary "$binary" Sub Type 0 / 0x00
"$binary" BsonLegacyUuid 5 / 0x05 BsonLegacyUuid "$binary" Sub Type 3 / 0x03
"$binary" BsonUuid 5 / 0x05 BsonUuid "$binary" Sub Type 4 / 0x04
"$oid" BsonObjectId 7 / 0x07 BsonObjectId "$oid"
bool BsonBoolean 8 / 0x08 BsonBoolean bool
"$date" BsonDate 9 / 0x09 BsonDate "$date"
Null BsonNull 10 / 0x0A BsonNull Null
"$regularExpression" BsonRegexp 11 / 0x0B BsonRegexp "$regularExpression"
"$dbPointer" DBPointer 12 / 0x0C DBPointer "$dbPointer" @Deprecated
"$code" BsonCode 13 / 0x0D BsonCode "$code"
int BsonInt 16 / 0x10 BsonInt "$numberInt" when bitLength <= 31
"$numberInt" BsonInt 16 / 0x10 BsonInt "$numberInt"
"$timestamp" BsonTimestamp 17 / 0x11 BsonTimestamp "$timestamp"
int BsonLong 18 / 0x12 BsonLong "$numberLong" when bitLength > 31
"$numberLong" BsonLong 18 / 0x12 BsonLong "$numberLong"
"$numberDecimal" BsonDecimal128 19 / 0x13 BsonDecimal128 "$numberDecimal"

To serialize an ejson map you have to use the serialize method of the EjsonCodec class. Serialization accept relaxed values, if present. Ex. var bsonBinary = EJsonCodec.serialize(ejsonMap); You can see a serialization example here

To deserialize an ejson map you have to use the deserialize method of the EjsonCodec class. Ex. var result = EJsonCodec.deserialize(bsonBinary); You can see a deserialization example here
To extract the ejson in "relaxed" format you have to set the relaxed parameter to true. Ex var result = EJsonCodec.deserialize(bsonBinary, relaxed: true);

There are also two convenient methods that you can use to convert from a ejson map into a Bson Map (EJsonCodec.eJson2Doc(ejsonMap)) and viceversa (EJsonCodec.doc2eJson(document)).

There are also two convenient method to transform an ejson map into a string (EJsonCodec.stringify) and vice-versa (EJsonCodec.parse).

Dart Object

You can also convert dart objects into BSON Format. The requirements are the following:

  • The object must use the BsonSerializable mixin.
  • Override the toBson method where, for each field, the corresponding value must be given. The value of one of the Bson managed ones or another object with the BsonSerializable mixin
  • Register the class with a unique number and the method you use for recreating the instance

To serialize a BsonSerializable object you have to use the serialize method of the object instance (inherithed from BsonSerializable). Ex. BsonBinary result = < bsonSerializable >.serialize(); You can see a serialization example here

To deserialize BsonSerializable object you have to use the deserialize method of the ObjectCodec class. Ex. ObjectCodec.deserialize(bsonBinary) You can see a deserialization example here