Swiftpack.co - Package - mongodb/mongo-swift-driver

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The official MongoDB driver for Swift.



The latest documentation is available here.

Bugs / Feature Requests

Think you've found a bug? Want to see a new feature in mongo-swift-driver? Please open a case in our issue management tool, JIRA:

  1. Create an account and login: jira.mongodb.org
  2. Navigate to the SWIFT project: jira.mongodb.org/browse/SWIFT
  3. Click Create Issue - Please provide as much information as possible about the issue and how to reproduce it.

Bug reports in JIRA for all driver projects (i.e. NODE, PYTHON, CSHARP, JAVA) and the Core Server (i.e. SERVER) project are public.


MongoSwift works with Swift 4.2+.

macOS and Linux

Installation on macOS and Linux is supported via Swift Package Manager.

Step 1: Install the MongoDB C Driver

The driver wraps the MongoDB C driver, and using it requires having the C driver's two components, libbson and libmongoc, installed on your system. The minimum required version of the C Driver is 1.13.0.

On a Mac, you can install both components at once using Homebrew: brew install mongo-c-driver.

On Linux: please follow the instructions from libmongoc's documentation. Note that the versions provided by your package manager may be too old, in which case you can follow the instructions for building and installing from source.

See example installation from source on Ubuntu in Docker.

Step 2: Install MongoSwift

Please follow the instructions in the previous section on installing the MongoDB C Driver before proceeding.

Add MongoSwift to your dependencies in Package.swift:

// swift-tools-version:4.2
import PackageDescription

let package = Package(
    name: "MyPackage",
    dependencies: [
        .package(url: "https://github.com/mongodb/mongo-swift-driver.git", from: "VERSION.STRING.HERE"),
    targets: [
        .target(name: "MyPackage", dependencies: ["MongoSwift"])

Then run swift build to download, compile, and link all your dependencies.

iOS, tvOS, and watchOS

Installation is supported via CocoaPods.

The pod includes as a dependency an embedded version of the MongoDB C Driver, meant for use on these OSes.

Note: the embedded driver currently does not support SSL. See #141 and CDRIVER-2850 for more information.

Add MongoSwift to your Podfile as follows:

platform :ios, '11.0'

target 'MyApp' do
    pod 'MongoSwift', '~> VERSION.STRING.HERE'

Then run pod install to install your project's dependencies.

Example Usage


You must call MongoSwift.initialize() once at the start of your application to initialize libmongoc. This initializes global state, such as process counters. Subsequent calls will have no effect.

You should call MongoSwift.cleanup() exactly once at the end of your application to release all memory and other resources allocated by libmongoc. MongoSwift.initialize() will not reinitialize the driver after MongoSwift.cleanup().

Connect to MongoDB and Create a Collection

import MongoSwift

// initialize global state

let client = try MongoClient(connectionString: "mongodb://localhost:27017")
let db = client.db("myDB")
let collection = try db.createCollection("myCollection")

// free all resources

Note: we have included the client connectionString for clarity, but if connecting to the default "mongodb://localhost:27017"it may be omitted: let client = try MongoClient().

Create and Insert a Document

let doc: Document = ["_id": 100, "a": 1, "b": 2, "c": 3]
let result = try collection.insertOne(doc)
print(result?.insertedId ?? "") // prints `100`

Find Documents

let query: Document = ["a": 1]
let documents = try collection.find(query)
for d in documents {

Work With and Modify Documents

var doc: Document = ["a": 1, "b": 2, "c": 3]

print(doc) // prints `{"a" : 1, "b" : 2, "c" : 3}`
print(doc["a"] ?? "") // prints `1`

// Set a new value
doc["d"] = 4
print(doc) // prints `{"a" : 1, "b" : 2, "c" : 3, "d" : 4}`

// Using functional methods like map, filter:
let evensDoc = doc.filter { elem in
    guard let value = elem.value as? Int else {
        return false
    return value % 2 == 0
print(evensDoc) // prints `{ "b" : 2, "d" : 4 }`

let doubled = doc.map { elem -> Int in
    guard let value = elem.value as? Int else {
        return 0

    return value * 2
print(doubled) // prints `[2, 4, 6, 8]`

Note that Document conforms to Collection, so useful methods from Sequence and Collection are all available. However, runtime guarantees are not yet met for many of these methods.

Usage With Kitura and Vapor

The Examples/ directory contains sample projects that use the driver with Kitura and Vapor.

Development Instructions

See our development guide for instructions for building and testing the driver.


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v0.1.0 - Apr 18, 2019

We are pleased to announce the 0.1.0 release of the MongoDB Swift driver.

Release Highlights

Swift 5 Support

This release adds support for using the driver in Swift 5.0. It also drops support for Swift versions < 4.2.

Improved Error Reporting

This release re-organizes the errors thrown by the driver to more accurately represent their sources. In particular, we now throw four classes of errors: ServerError, UserError, RuntimeError, and EncodingError/DecodingError. Each type is described in detail in the error handling guide.

BSON Improvements

This release includes a number of improvements to the BSON library. In particular:

Improved Int Handling consistency in Document

We've improved the consistency of how Ints are read from and written to Documents. Previously, Int was encoded to BSON as an int32 if it could fit, or an int64 otherwise. This could lead to situations where Ints were not round tripped properly through Documents. Now, Int behaves as the type of integer it represents on a given architecture, which means it is always round-tripped correctly. (See here for details on Swift Int's variable bitwidth.)

On 64-bit systems:

  • Int is encoded as a BSON int64
  • BSON int32s are read out of documents as Int32s
  • BSON int64s are read out of documents as Ints
  • e.g. doc["a"] = 5 sets the "a" key of a document to the BSON int64 5, and doc["a"] returns Int(5)

On 32-bit systems:

  • Int is encoded as a BSON int32
  • BSON int32s are read out of documents as Ints
  • BSON int64s are read out of documents as Int64s

On both systems, Int32 and Int64 are encoded to BSON int32 and BSON int64, respectively.


To facilitate writing architecture-independent code (which is rare, since Swift support for 32-bit is extremely limited), we introduced the BSONNumber protocol, which all the numeric BSONValue types (Int32, Int64, Int, Double, and Decimal128) conform to. Conformance to this protocol allows conversion to any of the number types that BSON natively supports. However, the conversions will only return a value if the conversion is exact, and will return nil otherwise.

let a: BSONNumber = 5.2
a.int32Value // nil
a.doubleValue // Double(5.2)
let b: BSONNumber = 5.0
b.int32Value // int32(5)
b.doubleValue // Double(5.0)
let c: BSONNumber = Int32.max + 1
c.int32Value // nil
c.int64Value // Int64(2147483648)

// Example usage for when you know it's a number, but not what type of number it is and/or you don't care
let doc: Document = ["a": 5.0]
(doc["a"] as! BSONNumber).intValue // 5

New Types for Deprecated BSON Types

We've added new types for deprecated BSON types: Undefined, DBPointer, and Symbol. Previously, when extracted from a Document, values encoded as those types would be automatically converted to similar non-deprecated ones. Their types are now preserved.

bsonEquals added to BSONValue protocol

bsonEquals is now part of the BSONValue protocol. Statements that were previously written as bsonEquals(a, b) can now be written as a.bsonEquals(b). The old syntax is deprecated and will be removed in a future release.

Coding Strategies Introduced

We've introduced the concept of a Coding Strategy in this release, which allows the user to specify how certain values get encoded to and decoded from BSON using BSONEncoder / BSONDecoder. The provided strategies are heavily based on the encoding and decoding strategies used in Foundation's JSONEncoder/JSONDecoder, and are implemented to behave similarly. See the driver documentation (and Foundations docs) for information on how they can be used. An in-depth guide is forthcoming for usage in the driver.

let date = Date(timeIntervalSince1970: 1.5)
let codingOptions = BSONCoderOptions(dateCodingStrategy: .millisecondsSince1970)
let doc = try BSONEncoder(options: codingOptions).encode(["a": date]) // ["a": Int64(1500)]
try BSONDecoder(options: codingOptions).decode(DateWrapperA.self, from: doc).a.timeIntervalSince1970 // 1.5

Release Notes


  • [SWIFT-294] - TopologyDescription initializer doesn't clean up server descriptions array
  • [SWIFT-351] - Correctly encode strings with multi-byte UTF8 characters
  • [SWIFT-394] - Ensure all bson_ts are correctly cleaned up

New Feature

  • [SWIFT-276] - Implement workaround for Swift 5.0 byte alignment cap to enable Swift 5 support
  • [SWIFT-337] - Support setting of encoding/decoding strategies on client, database, and collection levels


  • [SWIFT-144] - Update CRUD API errors to match the new hierarchy
  • [SWIFT-221] - Provide better consistency around Int usage with Documents
  • [SWIFT-268] - Store bson_oid_t in ObjectId rather than creating one each time we need it
  • [SWIFT-299] - Introduce new errors and error types
  • [SWIFT-300] - Convert InsertManyResult to BulkWriteResult when insertMany throws BulkWriteError
  • [SWIFT-301] - Convert invalidCollection, invalidClient, invalidUri, and invalidResponse errors to internalError or fatalError
  • [SWIFT-302] - Convert invalidCursor errors to commandErrors, logicErrors and invalidArgument errors
  • [SWIFT-303] - Convert bsonParseError to internalError
  • [SWIFT-304] - Convert bsonEncodeError, bsonDecodeError, typeError to new error types
  • [SWIFT-305] - Convert readPreferenceError to invalid argument or logic errors
  • [SWIFT-310] - Remove old errors
  • [SWIFT-313] - Move RegularExpression.nsRegularExpression logic into a new NSRegularExpression initializer
  • [SWIFT-331] - Throw an error when a non-BSONEncoder is used in encode(to:) for all BSONValue types that we own
  • [SWIFT-332] - Throw an error when non-BSONDecoder is used in init(from: decoder) for BSONValue types
  • [SWIFT-352] - Test round-tripping of BSON types with native representations using the BSON corpus data
  • [SWIFT-356] - Round trip Symbols, DBPointers, and Undefineds correctly
  • [SWIFT-358] - Don't require connectionString label in MongoClient initializer
  • [SWIFT-372] - Include bsonEquals as part of BSONValue protocol
  • [SWIFT-379] - Improve error message for type mismatches when decoding driver introduced BSON types
  • [SWIFT-384] - Provide an internal accessor for `bson_t`s length
  • [SWIFT-390] - Make bson pointer access explicit