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SwagGen

SwagGen is a library and command line tool for parsing and generating code for OpenAPI/Swagger 3.0 specs, completely written in Swift.

Swagger 2 support has been removed. For Swagger 2 use version 3.0.2 or the swagger_2 branch

Swagger parser

It contains a Swagger library that can be used in Swift to load and parse Swagger specs.

Swagger code generator

SwagGen is command line tool that generates code from a OpenAPI/Swagger 3.0 spec. Templates for any language can be written that leverage this generator.

Swift template

SwagGen includes a bundled template for generating a client side Swift library for interfacing with the Swagger spec. It includes support for model inheritance, shared enums, discrete and mutable request objects, inline schemas, Codable and Equatable models, configurable options, generic networking stack, and many other niceties.

Installing

Make sure Xcode 11+ is installed first.

Mint

$ mint install yonaskolb/SwagGen

Homebrew

$ brew tap yonaskolb/SwagGen https://github.com/yonaskolb/SwagGen.git
$ brew install SwagGen

Make

$ git clone https://github.com/yonaskolb/SwagGen.git
$ cd SwagGen
$ make install

Swift Package Manager

Use as CLI

$ git clone https://github.com/yonaskolb/SwagGen.git
$ cd swaggen
$ swift run

Use as dependency

Add the following to your Package.swift file's dependencies:

.package(url: "https://github.com/yonaskolb/SwagGen.git", from: "4.4.0"),

And then import wherever needed:

import SwagGenKit
import Swagger

Usage

Use --help to see usage information

swaggen --help
Usage: swaggen <command> [options]

Commands:
  generate        Generates a template from a Swagger spec
  help            Prints this help information
  version         Prints the current version of this app

generate

swaggen generate path_to_spec

Use swaggen generate --help to see the list of generation options.

• spec: This is the path to the Swagger spec and is a required parameter. It can either be a file path or a web url to a YAML or JSON file

• --language: The language to generate a template for. This defaults to swift for now.

• --template:: This is the path to the template config yaml file. It can either be a direct path to the file, or a path to the parent directory which will by default look for /template.yml. If this is not passed, the default template for the language will be used.

• --destination: The directory that the generated files will be added to.

• --option: An option that will be merged with the template config options with those in this argument taking precedence, meaning any existing options of the same name will be overwritten. This argument can be repeated to pass in multiple options. Options must specify the option name and option value separated by a colon, with any spaces contained in quotes. Nested options in dictionaries can be set by using a dot syntax. The following formats are allowed:

  • -- option myOption:myValue
  • -- option modelSuffix: Model
  • -- option propertyNames.identifier: id
  • -- option "myOption: my value"

• --clean: Controls if and how the destination directory is cleaned of non generated files. Options are:

  • none: no files are removed (default)
  • all: all other files are removed
  • leave.files: all files and directories except those that start with . in the destination directory are removed. This is useful for keeping configuration files and directories such as .git around, while still making sure that items removed from the spec are removed from the generated API.

• --verbose: Show more verbose output

• --silent: Silences any standard output. Errors will still be shown

Example:

swaggen generate http://myapi.com/spec --template Templates/Swift  --destination generated --option name:MyAPI --option "customProperty: custom value --clean leave.files"

For the Swift template, a handy option is name, which changes the name of the generated framework from the default of API. This can be set in the template or by passing in --option name:MyCoolAPI.

Swift Template

List of all available options:

name	action	expected values	default value
name	name of the API	String	API
authors	authors in podspec	String	Yonas Kolb
baseURL	baseURL in APIClient	String	first scheme, host, and base path of spec
fixedWidthIntegers	whether to use types like Int32 and Int64	Bool	false
homepage	homepage in podspec	String	https://github.com/yonaskolb/SwagGen
modelPrefix	model by adding a prefix and model file name	String	null
modelSuffix	model by adding a suffix and model file name	String	null
mutableModels	whether model properties are mutable	Bool	true
modelType	whether each model is a struct or class	String	class
modelInheritance	whether models use inheritance. Must be false for structs	Bool	true
modelNames	override model names	[String: String]	[:]
modelProtocol	customize protocol name that all models conform to	String	APIModel
enumNames	override enum names	[String: String]	[:]
enumUndecodableCase	whether to add undecodable case to enums	Bool	false
propertyNames	override property names	[String: String]	[:]
safeArrayDecoding	filter out invalid items in array instead of throwing	Bool	false
safeOptionalDecoding	set invalid optionals to nil instead of throwing	Bool	false
tagPrefix	prefix for all tags	String	null
tagSuffix	suffix for all tags	String	null
codableResponses	constrains all responses to be Codable	Bool	false
anyType	override Any with custom type	String	Any
numberType	override default number type when format not specified	String	Double

If writing your own Swift template there are a few types that are generated that you will need to provide typealias's for:

• ID: The UUID format. Usually UUID or String
• File: The file format. Usually URL, Data or a custom type with a mimeType and fileName
• DateTime: The date-time format. Usually Date
• DateDay: The date format. Usually Date or a custom type.

Development

If you want to pass any required arguments when running in Xcode, you can edit the scheme to include launch arguments.

Templates

Templates are made up of a template config file, a bunch of Stencil files, and other files that will be copied over during generation

Template config

This is the configuration and manifest file for the template in YAML or JSON format. It can contain:

• formatter: Optional formatter to use. This affects what properties are available in the templates and how they are formatted e.g. Swift
• templateFiles: a list of template files. These can each have their paths, contents and destination directories modified through Stencil tags. One template file can also output to multiple files if they path is changed depending on a list context. Each file contains:
  • path: relative path to the template config. The extension is usually .stencil or the type it is going to end up as
  • context: optional context within the spec. This is provided to the generated file, otherwise the full context will be passed. If this is a list then a file will be created for each object and the context within that list is used. (e.g. a file for every model in the spec definitions gets it's own definition context). Note that properties in the template options field can be used here
  • destination: optional destination path. This can contain stencil tags whose context is that from the context above. e.g. if context was definitions then the path could be Models/{{ type }}.swift and the filename would be the type of the definition. If this is left out the destination will be the same as the path, relative to the final destination directory. If it resolves to an empty string it will be skipped and not generated.
• copiedFiles: this is an array of relative paths that will be copied to the destination. They can be files or directories. This is used for files that won't have their contents, filenames or paths changed.
• options: these are the options passed into every stencil file and can be used to customize the template. These options are merged with the options argument, with the argument options taking precendance. These options can be references in template file paths and their contents.

An example template for Swift can be found here

Template Files

These files follow the Stencil file format outlined here https://stencil.fuller.li

Formatters

Formatters change what information is available to the templates and how it's formatted. They can be specified via the formatter property in the template config. Usually these would map to a specific target language, but can be customized for different purposes.

Output Languages

SwagGen can be used to generate code for any language. At the moment there is only a formatter and template for Swift

Swift API usage

Usage documentation can be found in the Readme that is generated with your template.

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Attributions

This tool is powered by:

• JSONUtilities
• Stencil
• StencilSwiftKit
• Spectre
• PathKit
• SwiftCLI
• Yams

Thanks also to Logan Shire and his initial work on Swagger Parser

Alternatives

• swagger-codegen
• CreateAPI
• OpenAPI Generator
• swift-openapi-generator

Contributions

Pull requests and issues are welcome

License

SwagGen is licensed under the MIT license. See LICENSE for more info.