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https://github.com/QueryKit/QueryKit
A simple CoreData query language for Swift and Objective-C.
https://github.com/QueryKit/QueryKit
Last synced: 12 days ago
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A simple CoreData query language for Swift and Objective-C.
- Host: GitHub
- URL: https://github.com/QueryKit/QueryKit
- Owner: QueryKit
- License: bsd-2-clause
- Created: 2014-06-07T01:54:56.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2021-06-10T17:29:14.000Z (over 3 years ago)
- Last Synced: 2024-05-17T00:03:47.224Z (6 months ago)
- Language: Swift
- Homepage: http://querykit.org/
- Size: 222 KB
- Stars: 1,456
- Watchers: 38
- Forks: 96
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
# QueryKit
QueryKit, a simple type-safe Core Data query language.
## Usage
```swift
QuerySet(context, "Person")
.orderedBy(.name, ascending: true)
.filter(\.age >= 18)
```
### QuerySet
A QuerySet represents a collection of objects from your Core Data Store.
It may have zero, one or many filters. Filters narrow down the query
results based on the given parameters.
#### Retrieving all objects
```swift
let queryset = QuerySet(context, "Person")
```
#### Retrieving specific objects with filters
You may filter a QuerySet using the `filter` and `exclude` methods, which
accept a predicate which can be constructed using KeyPath extensions.
The `filter` and `exclude` methods return new QuerySet's including your filter.
```swift
queryset.filter(\.name == "Kyle")
queryset.exclude(\.age > 25)
```
You may also use standard `NSPredicate` if you want to construct complicated
queries or do not wish to use the type-safe properties.
```swift
queryset.filter(NSPredicate(format: "name == '%@'", "Kyle"))
queryset.exclude(NSPredicate(format: "age > 25"))
```
##### Chaining filters
The result of refining a QuerySet is itself a QuerySet, so it’s possible
to chain refinements together. For example:
```swift
queryset.filter(\.name == "Kyle")
.exclude(\.age < 25)
```
Each time you refine a QuerySet, you get a new QuerySet instance that is in no
way bound to the previous QuerySet. Each refinement creates a separate and
distinct QuerySet that may be stored, used and reused.
#### QuerySets are lazy
A QuerySet is lazy, creating a QuerySet doesn’t involve querying
Core Data. QueryKit won’t actually execute the query until the
QuerySet is *evaluated*.
#### Ordering
You may order a QuerySet's results by using the `orderBy` function which
accepts a KeyPath.
```swift
queryset.orderBy(\.name, ascending: true)
```
You may also pass in an `NSSortDescriptor` if you would rather.
```swift
queryset.orderBy(NSSortDescriptor(key: "name", ascending: true))
```
#### Slicing
Using slicing, a QuerySet's results may be limited to a specified range. For
example, to get the first 5 items in our QuerySet:
```swift
queryset[0...5]
```
**NOTE**: *Remember, QuerySets are lazily evaluated. Slicing doesn’t evaluate the query.*
#### Fetching
##### Multiple objects
You may convert a QuerySet to an array using the `array()` function. For example:
```swift
for person in try! queryset.array() {
println("Hello \(person.name).")
}
```
##### First object
```swift
let kyle = try? queryset.first()
```
##### Last object
```swift
let kyle = try? queryset.last()
```
##### Object at index
```swift
let katie = try? queryset.object(3)
```
##### Count
```swift
let numberOfPeople = try? queryset.count()
```
##### Deleting
This method immediately deletes the objects in your queryset and returns a
count or an error if the operation failed.
```swift
let deleted = try? queryset.delete()
```
##### Operators
QueryKit provides KeyPath extensions providing operator functions allowing you
to create predicates.
```swift
// Name is equal to Kyle
\Person.name == "Kyle"
// Name is either equal to Kyle or Katie
\.Person.name << ["Kyle", "Katie"]
// Age is equal to 27
\.Person.age == 27
// Age is more than or equal to 25
\Person.age >= 25
// Age is within the range 22 to 30.
\Person.age << (22...30)
```
The following types of comparisons are supported using Attribute:
| Comparison | Meaning |
| ------- |:--------:|
| == | x equals y |
| != | x is not equal to y |
| < | x is less than y |
| <= | x is less than or equal to y |
| > | x is more than y |
| >= | x is more than or equal to y |
| ~= | x is like y |
| ~= | x is like y |
| << | x IN y, where y is an array |
| << | x BETWEEN y, where y is a range |
##### Predicate extensions
QueryKit provides the `!`, `&&` and `||` operators for joining multiple predicates together.
```swift
// Persons name is Kyle or Katie
\Person.name == "Kyle" || \Person.name == "Katie"
// Persons age is more than 25 and their name is Kyle
\Person.age >= 25 && \Person.name == "Kyle"
// Persons name is not Kyle
!(\Person.name == "Kyle")
```
## Installation
[CocoaPods](http://cocoapods.org) is the recommended way to add QueryKit to
your project, you may also use Carthage.
```ruby
pod 'QueryKit'
```
## License
QueryKit is released under the BSD license. See [LICENSE](LICENSE).