Encoding and decoding support for BSON in Rust
- Installation
- Useful links
- Overview of BSON Format
- Usage
- Contributing
- Running the Tests
- Continuous Integration
- Rust 1.48+
This crate is available on crates.io. To use it in your application, simply add it to your project's Cargo.toml.
[dependencies]
bson = "2.11.0"Note that if you are using bson through the mongodb crate, you do not need to specify it in your
Cargo.toml, since the mongodb crate already re-exports it.
| Feature | Description | Extra dependencies | Default |
|---|---|---|---|
chrono-0_4 |
Enable support for v0.4 of the chrono crate in the public API. |
n/a | no |
uuid-0_8 |
Enable support for v0.8 of the uuid crate in the public API. |
n/a | no |
uuid-1 |
Enable support for v1.x of the uuid crate in the public API. |
n/a | no |
serde_with |
Enable serde_with 1.x integrations for bson::DateTime and bson::Uuid. |
serde_with | no |
serde_with-3 |
Enable serde_with 3.x integrations for bson::DateTime and bson::Uuid. |
serde_with | no |
BSON, short for Binary JSON, is a binary-encoded serialization of JSON-like documents. Like JSON, BSON supports the embedding of documents and arrays within other documents and arrays. BSON also contains extensions that allow representation of data types that are not part of the JSON spec. For example, BSON has a datetime type and a binary data type.
// JSON equivalent
{"hello": "world"}
// BSON encoding
\x16\x00\x00\x00 // total document size
\x02 // 0x02 = type String
hello\x00 // field name
\x06\x00\x00\x00world\x00 // field value
\x00 // 0x00 = type EOO ('end of object')
BSON is the primary data representation for MongoDB, and this crate is used in the
mongodb driver crate in its API and implementation.
For more information about BSON itself, see bsonspec.org.
Many different types can be represented as a BSON value, including 32-bit and 64-bit signed
integers, 64 bit floating point numbers, strings, datetimes, embedded documents, and more. To
see a full list of possible BSON values, see the BSON specification. The various
possible BSON values are modeled in this crate by the Bson enum.
Creating Bson instances
Bson values can be instantiated directly or via the
bson! macro:
let string = Bson::String("hello world".to_string());
let int = Bson::Int32(5);
let array = Bson::Array(vec![Bson::Int32(5), Bson::Boolean(false)]);
let string: Bson = "hello world".into();
let int: Bson = 5i32.into();
let string = bson!("hello world");
let int = bson!(5);
let array = bson!([5, false]);bson! supports both array and object literals, and it automatically converts any values specified to Bson, provided they are Into<Bson>.
Bson value unwrapping
Bson has a number of helper methods for accessing the underlying native Rust types. These helpers can be useful in circumstances in which the specific type of a BSON value
is known ahead of time.
e.g.:
let value = Bson::Int32(5);
let int = value.as_i32(); // Some(5)
let bool = value.as_bool(); // None
let value = bson!([true]);
let array = value.as_array(); // Some(&Vec<Bson>)BSON documents are ordered maps of UTF-8 encoded strings to BSON values. They are logically similar to JSON objects in that they can contain subdocuments, arrays, and values of several different types. This crate models BSON documents via the
Document struct.
Creating Documents
Documents can be created directly either from a byte
reader containing BSON data or via the doc! macro:
let mut bytes = hex::decode("0C0000001069000100000000").unwrap();
let doc = Document::from_reader(&mut bytes.as_slice()).unwrap(); // { "i": 1 }
let doc = doc! {
"hello": "world",
"int": 5,
"subdoc": { "cat": true },
};doc! works similarly to bson!, except that it always
returns a Document rather than a Bson.
Document member access
Document has a number of methods on it to facilitate member
access:
let doc = doc! {
"string": "string",
"bool": true,
"i32": 5,
"doc": { "x": true },
};
// attempt get values as untyped Bson
let none = doc.get("asdfadsf"); // None
let value = doc.get("string"); // Some(&Bson::String("string"))
// attempt to get values with explicit typing
let string = doc.get_str("string"); // Ok("string")
let subdoc = doc.get_document("doc"); // Some(Document({ "x": true }))
let error = doc.get_i64("i32"); // Err(...)While it is possible to work with documents and BSON values directly, it will often introduce a
lot of boilerplate for verifying the necessary keys are present and their values are the correct
types. serde provides a powerful way of mapping BSON data into Rust data structures largely
automatically, removing the need for all that boilerplate.
e.g.:
#[derive(Serialize, Deserialize)]
struct Person {
name: String,
age: i32,
phones: Vec<String>,
}
// Some BSON input data as a `Bson`.
let bson_data: Bson = bson!({
"name": "John Doe",
"age": 43,
"phones": [
"+44 1234567",
"+44 2345678"
]
});
// Deserialize the Person struct from the BSON data, automatically
// verifying that the necessary keys are present and that they are of
// the correct types.
let mut person: Person = bson::from_bson(bson_data).unwrap();
// Do things just like with any other Rust data structure.
println!("Redacting {}'s record.", person.name);
person.name = "REDACTED".to_string();
// Get a serialized version of the input data as a `Bson`.
let redacted_bson = bson::to_bson(&person).unwrap();Any types that implement Serialize and Deserialize can be used in this way. Doing so helps
separate the "business logic" that operates over the data from the (de)serialization logic that
translates the data to/from its serialized form. This can lead to more clear and concise code
that is also less error prone.
The BSON format includes a datetime type, which is modeled in this crate by the
bson::DateTime struct, and the
Serialize and Deserialize implementations for this struct produce and parse BSON datetimes when
serializing to or deserializing from BSON. The popular crate chrono also
provides a DateTime type, but its Serialize and Deserialize implementations operate on strings
instead, so when using it with BSON, the BSON datetime type is not used. To work around this, the
chrono-0_4 feature flag can be enabled. This flag exposes a number of convenient conversions
between bson::DateTime and chrono::DateTime, including the
chrono_datetime_as_bson_datetime
serde helper, which can be used to (de)serialize chrono::DateTimes to/from BSON datetimes, and the
From<chrono::DateTime> implementation for Bson, which allows chrono::DateTime values to be
used in the doc! and bson! macros.
e.g.
use serde::{Serialize, Deserialize};
#[derive(Serialize, Deserialize)]
struct Foo {
// serializes as a BSON datetime.
date_time: bson::DateTime,
// serializes as an RFC 3339 / ISO-8601 string.
chrono_datetime: chrono::DateTime<chrono::Utc>,
// serializes as a BSON datetime.
// this requires the "chrono-0_4" feature flag
#[serde(with = "bson::serde_helpers::chrono_datetime_as_bson_datetime")]
chrono_as_bson: chrono::DateTime<chrono::Utc>,
}
// this automatic conversion also requires the "chrono-0_4" feature flag
let query = doc! {
"created_at": chrono::Utc::now(),
};See the module-level documentation for the bson::uuid module.
This crate compiles to the wasm32-unknown-unknown target; when doing so, the js-sys crate is used for the current timestamp component of ObjectId generation.
The MSRV for this crate is currently 1.64.0. This will be rarely be increased, and if it ever is, it will only happen in a minor or major version release.
We encourage and would happily accept contributions in the form of GitHub pull requests. Before opening one, be sure to run the tests locally; check out the testing section for information on how to do that. Once you open a pull request, your branch will be run against the same testing matrix that we use for our continuous integration system, so it is usually sufficient to only run the integration tests locally against a standalone. Remember to always run the linter tests before opening a pull request.
To actually run the tests, you can use cargo like you would in any other crate:
cargo test --verbose # runs against localhost:27017Our linter tests use the nightly version of rustfmt to verify that the source is formatted properly and the stable version of clippy to statically detect any common mistakes.
You can use rustup to install them both:
rustup component add clippy --toolchain stable
rustup component add rustfmt --toolchain nightlyTo run the linter tests, run the check-clippy.sh and check-rustfmt.sh scripts in the .evergreen directory:
bash .evergreen/check-clippy.sh && bash .evergreen/check-rustfmt.shCommits to main are run automatically on evergreen.
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