Kuery

Kuery, a type-safe Core Data query API using Swift 4's Smart KeyPaths. Inspired and borrowed a lot of things from QueryKit and RealmEx.

Requirements

Kuery is written in Swift 4.

Installation

CocoaPods

Kuery is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'Kuery'

Carthage

For Carthage, add the following to your Cartfile:

github "kishikawakatsumi/Kuery"

Description

Kuery provides type safety, code completion and avoidance of typos against NSPredicate queries.

Before

NSPredicate(format: "name == %@", "Katsumi")
NSPredicate(format: "age > %@", 20)

After

Query(Person.self).filter(\Person.name == "Katsumi")
Query(Person.self).filter(\Person.age > 20)

The following code should be a compile error.

Query(Person.self).filter(\Person.name > 20) // Compile error
Query(Person.self).filter(\Dog.name == "John") // Compile error

Usage

context.perform {
    let results = try Query(Person.self)
        .filter(\Person.name == "Katsumi")
        .execute()
}

context.perform {
    let results = try Query(Person.self)
        .filter(\Person.age == 36)
        .execute()
}

context.perform {
    let results = try Query(Person.self)
        .filter(\Person.age > 20)
        .execute()
}

context.perform {
    let results = try Query(Person.self)
        .filter(\Person.name == "Katsumi")
        .filter(\Person.age == 36)
        .execute()
}

context.perform {
    let results = try Query(Dog.self)
        .filter(\Dog.owner == person)
        .execute()
}

Feature request for Swift Standard Library

It requires a string representation of KeyPath to construct NSPredicate from KeyPath. However, the API is not officially visible currently. The feature request is tracked at SR-5220.

[SR-5220] Expose API to retrieve string representation of KeyPath - Swift