You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
125 lines
7.3 KiB
125 lines
7.3 KiB
// Copyright (C) MongoDB, Inc. 2017-present.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
// not use this file except in compliance with the License. You may obtain
|
|
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
// Package bson is a library for reading, writing, and manipulating BSON. BSON is a binary serialization format used to
|
|
// store documents and make remote procedure calls in MongoDB. The BSON specification is located at https://bsonspec.org.
|
|
// The BSON library handles marshalling and unmarshalling of values through a configurable codec system. For a description
|
|
// of the codec system and examples of registering custom codecs, see the bsoncodec package.
|
|
//
|
|
// Raw BSON
|
|
//
|
|
// The Raw family of types is used to validate and retrieve elements from a slice of bytes. This
|
|
// type is most useful when you want do lookups on BSON bytes without unmarshaling it into another
|
|
// type.
|
|
//
|
|
// Example:
|
|
// var raw bson.Raw = ... // bytes from somewhere
|
|
// err := raw.Validate()
|
|
// if err != nil { return err }
|
|
// val := raw.Lookup("foo")
|
|
// i32, ok := val.Int32OK()
|
|
// // do something with i32...
|
|
//
|
|
// Native Go Types
|
|
//
|
|
// The D and M types defined in this package can be used to build representations of BSON using native Go types. D is a
|
|
// slice and M is a map. For more information about the use cases for these types, see the documentation on the type
|
|
// definitions.
|
|
//
|
|
// Example:
|
|
// bson.D{{"foo", "bar"}, {"hello", "world"}, {"pi", 3.14159}}
|
|
// bson.M{"foo": "bar", "hello": "world", "pi": 3.14159}
|
|
//
|
|
// When decoding BSON to a D or M, the following type mappings apply when unmarshalling:
|
|
//
|
|
// 1. BSON int32 unmarshals to an int32.
|
|
// 2. BSON int64 unmarshals to an int64.
|
|
// 3. BSON double unmarshals to a float64.
|
|
// 4. BSON string unmarshals to a string.
|
|
// 5. BSON boolean unmarshals to a bool.
|
|
// 6. BSON embedded document unmarshals to the parent type (i.e. D for a D, M for an M).
|
|
// 7. BSON array unmarshals to a bson.A.
|
|
// 8. BSON ObjectId unmarshals to a primitive.ObjectID.
|
|
// 9. BSON datetime unmarshals to a primitive.Datetime.
|
|
// 10. BSON binary unmarshals to a primitive.Binary.
|
|
// 11. BSON regular expression unmarshals to a primitive.Regex.
|
|
// 12. BSON JavaScript unmarshals to a primitive.JavaScript.
|
|
// 13. BSON code with scope unmarshals to a primitive.CodeWithScope.
|
|
// 14. BSON timestamp unmarshals to an primitive.Timestamp.
|
|
// 15. BSON 128-bit decimal unmarshals to an primitive.Decimal128.
|
|
// 16. BSON min key unmarshals to an primitive.MinKey.
|
|
// 17. BSON max key unmarshals to an primitive.MaxKey.
|
|
// 18. BSON undefined unmarshals to a primitive.Undefined.
|
|
// 19. BSON null unmarshals to nil.
|
|
// 20. BSON DBPointer unmarshals to a primitive.DBPointer.
|
|
// 21. BSON symbol unmarshals to a primitive.Symbol.
|
|
//
|
|
// The above mappings also apply when marshalling a D or M to BSON. Some other useful marshalling mappings are:
|
|
//
|
|
// 1. time.Time marshals to a BSON datetime.
|
|
// 2. int8, int16, and int32 marshal to a BSON int32.
|
|
// 3. int marshals to a BSON int32 if the value is between math.MinInt32 and math.MaxInt32, inclusive, and a BSON int64
|
|
// otherwise.
|
|
// 4. int64 marshals to BSON int64.
|
|
// 5. uint8 and uint16 marshal to a BSON int32.
|
|
// 6. uint, uint32, and uint64 marshal to a BSON int32 if the value is between math.MinInt32 and math.MaxInt32,
|
|
// inclusive, and BSON int64 otherwise.
|
|
// 7. BSON null and undefined values will unmarshal into the zero value of a field (e.g. unmarshalling a BSON null or
|
|
// undefined value into a string will yield the empty string.).
|
|
//
|
|
// Structs
|
|
//
|
|
// Structs can be marshalled/unmarshalled to/from BSON or Extended JSON. When transforming structs to/from BSON or Extended
|
|
// JSON, the following rules apply:
|
|
//
|
|
// 1. Only exported fields in structs will be marshalled or unmarshalled.
|
|
//
|
|
// 2. When marshalling a struct, each field will be lowercased to generate the key for the corresponding BSON element.
|
|
// For example, a struct field named "Foo" will generate key "foo". This can be overriden via a struct tag (e.g.
|
|
// `bson:"fooField"` to generate key "fooField" instead).
|
|
//
|
|
// 3. An embedded struct field is marshalled as a subdocument. The key will be the lowercased name of the field's type.
|
|
//
|
|
// 4. A pointer field is marshalled as the underlying type if the pointer is non-nil. If the pointer is nil, it is
|
|
// marshalled as a BSON null value.
|
|
//
|
|
// 5. When unmarshalling, a field of type interface{} will follow the D/M type mappings listed above. BSON documents
|
|
// unmarshalled into an interface{} field will be unmarshalled as a D.
|
|
//
|
|
// The encoding of each struct field can be customized by the "bson" struct tag.
|
|
// The tag gives the name of the field, possibly followed by a comma-separated list of options.
|
|
// The name may be empty in order to specify options without overriding the default field name. The following options can be used
|
|
// to configure behavior:
|
|
//
|
|
// 1. omitempty: If the omitempty struct tag is specified on a field, the field will not be marshalled if it is set to
|
|
// the zero value. By default, a struct field is only considered empty if the field's type implements the Zeroer
|
|
// interface and the IsZero method returns true. Struct fields of types that do not implement Zeroer are always
|
|
// marshalled as embedded documents. This tag should be used for all slice and map values.
|
|
//
|
|
// 2. minsize: If the minsize struct tag is specified on a field of type int64, uint, uint32, or uint64 and the value of
|
|
// the field can fit in a signed int32, the field will be serialized as a BSON int32 rather than a BSON int64. For other
|
|
// types, this tag is ignored.
|
|
//
|
|
// 3. truncate: If the truncate struct tag is specified on a field with a non-float numeric type, BSON doubles unmarshalled
|
|
// into that field will be trucated at the decimal point. For example, if 3.14 is unmarshalled into a field of type int,
|
|
// it will be unmarshalled as 3. If this tag is not specified, the decoder will throw an error if the value cannot be
|
|
// decoded without losing precision. For float64 or non-numeric types, this tag is ignored.
|
|
//
|
|
// 4. inline: If the inline struct tag is specified for a struct or map field, the field will be "flattened" when
|
|
// marshalling and "un-flattened" when unmarshalling. This means that all of the fields in that struct/map will be
|
|
// pulled up one level and will become top-level fields rather than being fields in a nested document. For example, if a
|
|
// map field named "Map" with value map[string]interface{}{"foo": "bar"} is inlined, the resulting document will be
|
|
// {"foo": "bar"} instead of {"map": {"foo": "bar"}}. There can only be one inlined map field in a struct. If there are
|
|
// duplicated fields in the resulting document when an inlined struct is marshalled, the inlined field will be overwritten.
|
|
// If there are duplicated fields in the resulting document when an inlined map is marshalled, an error will be returned.
|
|
// This tag can be used with fields that are pointers to structs. If an inlined pointer field is nil, it will not be
|
|
// marshalled. For fields that are not maps or structs, this tag is ignored.
|
|
//
|
|
// Marshalling and Unmarshalling
|
|
//
|
|
// Manually marshalling and unmarshalling can be done with the Marshal and Unmarshal family of functions.
|
|
package bson
|