Barrel

A simple type-safe library for NSPredicate and NSExpresion.

Installation

You can use Carthage to install Barrel by adding it to your Cartfile:

github "tarunon/Barrel"

Summary

Extend your class/struct A and AttributeType like.

struct A: SelfExpression {
    var text: String
    var number: Int
    var option: String?
}

extension AttributeType where ValueType: A {
    var text: Attribute<String> { return attribute() }
    var number: Attribute<Int> { return attribute() }
    var option: Attribute<Optional<String>> { return attribute() }
}

Make NSPredicate and NSExpression from Attribute<A>.

var attribute = Attribute<A>()
var predicate = attribute.text == "TEXT" // predicate.value is NSPredicate
var expression = attribute.number.max() // expression.value is NSExpression

Attribute

Extend AttributeType using computed property one by one ValueType. Computed properties are Attribute<T> and return "attribute()".

Expression

Make Expression by AttributeType. If AttributeType's ValueType like Number, you can use max, min, sum, average, or +, -, /, * with other Attribute or Number. Make kyepath expression using unwrapExpression.

var maxExpression = attribute.number.max()
var plus1Expression = attribute.number + 1
var keyPathExpression = unwrapExpression(attribute.text)

Predicate

Make Predicate by AttributeType Support operand (==, !=, <, <=, >=, >, <<) Operand "<<" means in array or between range. If AttributeType's ValueType is String, you can use contains, beginsWith, endsWith, maches method. If AttributeType's ValueType like many-relationships, you can use any, all method by make struct extend ManyType.

var equalToPredicate = attribute.text == "TEST"
var containsPredicate = attribute.text.contains("A")

struct Many<T: ExpressionType>: ManyType {
    typealias ValueType = [T]
    typealias ElementType = T
}

extension AttributeType where ValueType == A {
    var array: Attribute<Many<A>> { return attribute() }
}

var anyPredicate = attribute.array.any { $0.number > 0 }

SortDescriptors

Make SortDescriptors by AttributeType

var ascending = attribute.number < attribute.number

Support Types

Barrel Support types listed String, Int, Double, Float, Bool, Int16, Int32, Int64, Array, Dictionary, Set, NSDate, NSData, NSNumber If you needs support more type, plese implement SelfExpression.

extension Type: SelfExpression {}

Class support

We cannot an associatedtype conform to Self in class after Swift 3.1. ExpressionWrapper is workaround that instead of conform to Self. Write * before use class value in query.

var predicate = attribute.someClassField == *classValue

And define attribute value surround ExpressionWrapper.

extension AttributeType where ValueType: SomeClass {
  var someClassField: Attribute<ExpressionWrapper<SomeFieldClass>> { return attribute() }
}

for Swift 3.x

Version 4.0.1 supports Swift 3.

LISENSE

MIT