Sourcery AutoJSONSerialization

This is my attempt to implement some Sourcery templates which automatically generates JSON bindings for your structs and classes.

My objective here is to provide a fully tested code generation template that will let you skip the pain of writing this code:

extension Contact: JSONDeserializable {
    enum Fields: String {
        case identifier = "id"
        case firstName = "first_name"
        case lastName = "last_name"
        case age = "age"
    }

    init?(JSONObject: Any) {
        guard let JSONObject = JSONObject as? [String: Any],
              let let id = JSONObject[Fields.identifier.rawValue] as? String,
              let firstName = JSONObject[Fields.firstName.rawValue] as? String,
              let lastName = JSONObject[Fields.lastName.rawValue] as? String,
              let age = JSONObject[Fields.age.rawValue] as? Int
            else {
                return nil
        }
        self.id = id
        self.firstName = firstName
        self.lastName = lastName
        self.age = age
    }
}

Usage

The JSON serialization/deserialization is based on two protocols.

protocol JSONDeserializable {
    init?(JSONObject: Any)
}

protocol JSONSerializable {
    func toJSONObject() -> Any
}

With this tool, you do not need to implement these protocols, the Sourcery templates will do the boiler plate code for you.
To do this, all you need to do is add sourcery annotations to you structs:

// sourcery: AutoJSONSerializable, AutoJSONDeserializable
struct Contact {
    // ...
}

And then run Sourcery using the templates found in the Templates/ folder of this repository.

Example

Let say you have a model struct like this one:

struct Contact {
    let id: String
    let firstName: String
    let lastName: String
    let age: Int
}

Adding the AutoJSONDeserializable annotation would make it initializable from this JSON data:

{
  "id": "SomeID",
  "firstName": "John",
  "lastName": "Doe'"
}

Features

• Primitive JSON types (String, Int, Double).
• RawRepresentable enums.
• Any type implementing JSONSerializable/JSONDeserializable.
• Optionals.
• Nested structures.
• Nested types with custom JSONSerializable or JSONDeserializable implementation.
• Arrays of primitive JSON types, enums and JSON*able types.
• JSONKey annotation.

⚠️ This system does not support class types because an extension can only declare convenience initializers ⚠️

⚠️ Dates are not supported out of the box anymore ⚠️

Because almost every project use a different date format to communicate with the server the embedded implementation has been removed. You can support Dates by providing your implementation.
However, you can still find an implementation for Dates Serialization/Deserialization using ISO8601DateFormatter with milliseconds support in the testing code here.

Attributes annotations

When mapping your JSON to your model structure, you may sometimes want to use a different attribute name as the one in the JSON file.
Let's say you have this JSON:

{
  "id": "SomeID",
  "first_name": "John",
  "last_name": "Doe'"
}

As you can see, the naming convention does not follow camel case. To fix this you can use Sourcery annotations.
On a property, you can define the JSONKey attribute with the JSON name you want to bind the property to:

struct Contact {
    let id: String
    // sourcery: JSONKey = "first_name"
    let firstName: String
    // sourcery: JSONKey = "last_name"
    let lastName: String
}

Custom JSON*able Implementation

If you want to nest some types that are not supported out of the box (e.g. enums with associated values) or if you want to provide a special implementation of the serde methods for those types, you can simply implement the JSONSerializable and/or JSONDeserializable protocols.

For example, if Job is an enum, you can still add it to Contact:

struct Contact {
    let id: String
    let job: Job
}

enum Job: JSONSerializable {
    […]

    func toJSONObject() -> Any {
        // Implemnt your custom serializer.
    }
}

You can find some examples in the models I use to test the library in Sources/AutoJSONSerialization/Models/.

Installation

With CocoaPods

Add pod 'Sourcery-AutoJSONSerializable' to your Podfile.

Configure your .sourcery.yml file with this:

[…]
templates:
  - Pods/Sourcery-AutoJSONSerializable/Templates/
  […]

And, to use it on a structure, just add one of the "Auto" annotation:

// sourcery: AutoJSONSerializable
struct Contact {
    [...]
}

This will generate two files to add to your project:

• AutoJSONSerializable.generated.swift
• AutoJSONDeserializable.generated.swift

You can specify the output folder for these files using the output option in your .sourcery.yml. See Soucery documentation for more details.

If you want to provide custom JSONSerializable or JSONDeserializable implementations, just import the module Sourcery_AutoJSONSerializable to gain access to the protocols.

Manual Install

To install just copy the following source files in your project:

• Sources/AutoJSONSerialization/JSONSerializable.swift
• Sources/AutoJSONSerialization/JSONDeserializable.swift

And then copy the Templates files and configure Sourcery.

Development

This library uses the Swift Package Manager to build the code with a Sourcery pre-build step described using a Makefile.
You can find all the possible build rules using the command make help.

Pod deployment

We offer a cocoapods installation which involves several steps to deliver new versions of the library.
This process is automated using fastlane and can be accessed using make. Here it what it'll do:

1. bump the podspec version and commit the change to the repository
2. create the corresponding tag
3. push the new version to github and to cocoapods trunk