https://github.com/gonzalezreal/defaultcodable
A convenient way to handle default values with Swift Codable types
https://github.com/gonzalezreal/defaultcodable
codable defaults property-wrapper swift
Last synced: 10 months ago
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A convenient way to handle default values with Swift Codable types
- Host: GitHub
- URL: https://github.com/gonzalezreal/defaultcodable
- Owner: gonzalezreal
- License: mit
- Created: 2020-02-07T15:59:25.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2021-06-12T17:08:37.000Z (over 4 years ago)
- Last Synced: 2025-03-30T17:09:13.735Z (10 months ago)
- Topics: codable, defaults, property-wrapper, swift
- Language: Swift
- Homepage:
- Size: 22.5 KB
- Stars: 357
- Watchers: 3
- Forks: 11
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# DefaultCodable
[](https://swift.org/package-manager)
[](https://twitter.com/gonzalezreal)
**DefaultCodable** is a Swift µpackage that provides a convenient way to define default values in `Codable` types for properties that are **not present or have a `nil` value**.
## Usage
Consider a hypothetical model for Apple products., in which only the property `name` is *required*.
```swift
enum ProductType: String, Codable, CaseIterable {
case phone, pad, mac, accesory
}
struct Product: Codable {
var name: String
var description: String?
var isAvailable: Bool?
var type: ProductType?
}
```
Using the `@Default` property wrapper, we can provide default values for the properties not required and thus get rid of the optionals in our model.
```swift
struct Product: Codable {
var name: String
@Default
var description: String
@Default
var isAvailable: Bool
@Default
var type: ProductType
}
```
With that in place, we can safely decode the following JSON into a `Product` type.
```json
{
"name": "iPhone 11 Pro"
}
```
The resulting `Product` instance is using the default values for those properties not present in the JSON.
```
▿ Product
- name : "iPhone 11 Pro"
- description : ""
- isAvailable : true
- type : ProductType.phone
```
If you encode the result back, the resulting JSON will be the same as the one we started with. The `@Default` property wrapper will not encode the value if it is equal to the default value.
The `@Default` property wrapper takes a `DefaultValueProvider` as a parameter. This type provides the default value when a value is not present or is `nil`.
```swift
protocol DefaultValueProvider {
associatedtype Value: Equatable & Codable
static var `default`: Value { get }
}
```
**DefaultCodable** provides the following implementations for your convenience:
### `Empty`
It provides an empty instance of a `String`, `Array` or any type that implements `RangeReplaceableCollection`.
### `EmptyDictionary`
It provides an empty instance of a `Dictionary`.
### `True` and `False`
Provide `true` and `false` respectively for `Bool` properties.
### `Zero` and `One`
Provide `0` and `1` respectively for `Int` properties.
### `FirstCase`
It provides the first case of an `enum` type as the default value. The `enum` must implement the `CaseIterable` protocol.
### `ZeroDouble`
Provide `0` for `Double` properties.
## Default values for custom types
Your custom type must implement the `DefaultValueProvider` protocol to be compatible with the `@Default` property wrapper.
Consider the following type that models a role in a conversation:
```swift
struct Role: Codable, Equatable, Hashable, RawRepresentable {
let rawValue: String
init?(rawValue: String) {
self.rawValue = rawValue
}
static let user = Role(rawValue: "user")!
static let bot = Role(rawValue: "bot")!
}
```
If we want the default role to be `user`, we can implement `DefaultValueProvider` as follows:
```swift
extension Role: DefaultValueProvider {
static let `default` = user
}
```
With that in place, we can use the `@Default` property wrapper in any type that has a property of type `Role`:
```swift
struct ChannelAccount: Codable {
var name: String
@Default
var role: Role
}
```
## Installation
**Using the Swift Package Manager**
Add **DefaultCodable** as a dependency to your `Package.swift` file. For more information, see the [Swift Package Manager documentation](https://github.com/apple/swift-package-manager/tree/master/Documentation).
```
.package(url: "https://github.com/gonzalezreal/DefaultCodable", from: "1.0.0")
```
## Help & Feedback
- [Open an issue](https://github.com/gonzalezreal/DefaultCodable/issues/new) if you need help, if you found a bug, or if you want to discuss a feature request.
- [Open a PR](https://github.com/gonzalezreal/DefaultCodable/pull/new/master) if you want to make some change to `DefaultCodable`.
- Contact [@gonzalezreal](https://twitter.com/gonzalezreal) on Twitter.