DIGEN - Dependency Injection Container Generator

Installation

Install on Linux

# binary will be $(go env GOPATH)/bin/digen
sh -c "$(curl --location https://raw.githubusercontent.com/strider2038/digen/master/install.sh)" -- -d -b $(go env GOPATH)/bin
digen version

Go installer

go install github.com/strider2038/digen/cmd/digen@latest
digen version

How to use

Initialize a new container

To initialize new container skeleton run command.

digen init

Then describe your service definitions in the Container struct (<workdir>/internal/definitions/container.go). See examples. After any update run digen generate command to generate container and factories.

File structure

• base directory (recommended name di)
  • container.go - generated public container
  • internal - directory with internal packages
    • container.go - generated internal di container
    • definitions - package with container and service definitions (configuration file)
      • container.go - structs describing di containers (describe here your services)
    • factories - package with manually written factory functions to build up services
  • lookup - directory with lookup container contracts
    • container.go - generated interfaces for internal di container (to use in factories package)

Service definition options

There are two ways to set up service definition options: by tags and by comments. When both are present, options by tags will override options by comments (flags will be merged).

• tag di for flag options:
  • set - to generate setters for internal and public containers;
  • close - to generate closer method call;
  • required - to generate argument for public container constructor;
  • public - to generate getter for public container.
• tag factory_pkg to set up factory package;
• tag factory_name to set up factory filename (without extension);
• tag public_name to override service getter for public container.

Example of definitions/container.go using tags.

type Container struct {
    Configuration config.Configuration `di:"required"`
    Logger        *log.Logger          `di:"required"`
    Conn          *sql.Conn            `di:"set,close"`

    Handler *httpadapter.GetEntityHandler `di:"public"`

    UseCases     UseCaseContainer
    Repositories RepositoryContainer
}

type UseCaseContainer struct {
    FindEntity *usecase.FindEntity
}

type RepositoryContainer struct {
    EntityRepository domain.EntityRepository `di:"set"`
}

Example of definitions/container.go using comments.

type Container struct {
    // di: required
    Configuration config.Configuration
    // di: required
    Logger *log.Logger
    // di: set,close
    Conn *sql.Conn

    // di: public
    // di: factory_pkg: example.com/test/infrastructure/api/http
    // di: factory_name: handler
    Handler *httpadapter.GetEntityHandler

    UseCases     UseCaseContainer
    Repositories RepositoryContainer
}

type UseCaseContainer struct {
    FindEntity *usecase.FindEntity
}

type RepositoryContainer struct {
    // di: set
    EntityRepository domain.EntityRepository
}

Configuration

DIGEN configuration can be presented in digen.yaml/digen.yml/digen.json file in the project root directory.

version: v0.2
container:
  # base directory with Dependency Injection Container files
  dir: di # required
factories:
  # option can be used to disable return error by default
  returnError: true
errorHandling:
  # options for error handling
  # default values described below, can be omitted
  new:
    pkg: 'fmt'
    func: 'Errorf'
  join:
    pkg: 'errors'
    func: 'Join'
  wrap:
    pkg: 'fmt'
    func: 'Errorf'
    verb: '%w'

TODO

• public container generator
• use cobra/viper
• SetError method
• generate package docs
• skeleton generation command (init)
• import definitions package
• remove unnecessary imports
• definitions generator
• handle multiple containers
• better console output via logger
• definitions for multiple containers
• unique names for separate container definitions
• prompt for init (set work_dir, write first config)
• better generation with _config.go file
• apply gofmt
• move contracts into separate package
• generate README.md for root package
• ability to choose specific file for factory func
• ability to set public definition name
• check app version in config
• force variable name / package name uniqueness
• custom close functions
• describe basic app example
• add complex app example with tests and fake repository
• definitions updater
• remove SetError method
• write doc