README

knifecycle

Manage your NodeJS processes's lifecycle automatically with an unobtrusive dependency injection implementation.

Most (maybe all) applications rely on two kinds of dependencies.

The code dependencies are fully covered by JavaScript modules in a testable manner (with mockery or System directly). There is no need for another dependency management system if those libraries are pure functions (involve no global states at all).

Unfortunately, applications often rely on global states where the JavaScript module system shows its limits. This is where knifecycle enters the game.

It is largely inspired by the Angular service system except it should not provide code but access to global states (time, filesystem, db). It also have an important additional feature to shutdown processes which is really useful for back-end servers and doesn't exists in Angular.

You may want to look at the architecture notes to better handle the reasonning behind knifecycle and its implementation.

At this point you may think that a DI system is useless. My advice is that it depends. But at least, you should not make a definitive choice and allow both approaches. See this StackOverflow answer for more context about this statement.

Features

services management: start services taking their dependencies in count and shut them down the same way for graceful exits (namely dependency injection with inverted control);
singleton: maintain singleton services across several running execution silos.
easy end to end testing: just replace your services per your own mocks and stubs while ensuring your application integrity between testing and production;
isolation: isolate processing in a clean manner, per concerns;
functional programming ready: encapsulate global states allowing the rest of your application to be purely functional;
no circular dependencies for services: while circular dependencies are not a problem within purely functional libraries (require allows it), it may be harmful for your services, knifecycle impeach that while providing an $injector service à la Angular to allow accessing existing services references if you really need to;
generate Mermaid graphs of the dependency tree;
build raw initialization modules to avoid embedding Knifecycle in your builds;
optionally autoload services dependencies with custom logic.

Usage

Using knifecycle is all about declaring the services our application needs and running your application over it.

Let's say we are building a CLI script. Here is how we would proceed with Knifecycle:

// bin.js
import fs from 'fs';
import YError from 'YError';
import Knifecycle, { initializer, constant, inject, name } from 'knifecycle';

// First of all we create a new Knifecycle instance
const $ = new Knifecycle();

// Some of our code with rely on the process environment
// let's inject it as a constant instead of directly
// pickking env vars in `process.env` to make our code
// easily testable
$.register(constant('ENV', process.env));

// Let's do so for CLI args with another constant
// in real world apps we would have created a service
// that would parse args in a complexer way
$.register(constant('ARGS', process.argv));

// We want our CLI tool to rely on some configuration
// Let's build an injectable service initializer that
// reads environment variables via an injected but
// optional `ENV` object
async function initConfig({ ENV = { CONFIG_PATH: '.' } }) {
  return new Promise((resolve, reject) => {
    fs.readFile(ENV.CONFIG_PATH, 'utf-8', (err, data) => {
      if (err) {
        reject(err);
        return;
      }
      try {
        resolve(JSON.parse(data));
      } catch (err) {
        reject(err);
      }
    });
  });
}

// We are using the `initializer` decorator to
// declare our service initializer specificities
// and register it with our Knifecycle instance
$.register(
  initializer(
    {
      // we have to give our final service a name
      // for further use in other services injections
      name: 'CONFIG',
      // we will need an `ENV` variable in the initializer
      // so adding it in the injected dependencies. The `?`
      // sign tells Knifecycle that the ENV dependency
      // is optional
      inject: ['?ENV'],
      // our initializer is simple so we use the `service`
      // type for the initializer which just indicate that
      // the initializer will return a promise of the actual
      // service
      type: 'service',
      // We don't want to read the config file everytime we
      // inject it so declaring it as a singleton
      singleton: true,
    },
    initConfig,
  ),
);

// Our CLI also uses a database so let's write an
// initializer for it:
const initDB = initializer(
  {
    name: 'db',
    // Here we are injecting the previous `CONFIG` service
    // as required so that our DB cannot be connected without
    // having a proper config.
    inject: ['CONFIG', 'DB_URI', '?log'],
    // The initializer type is slightly different. Indeed,
    // we need to manage the database connection errors
    // and wait for it to flush before shutting down the
    // process.
    // A service provider returns a promise of a provider
    // descriptor exposing:
    // - a mandatory `service` property containing the
    // actual service;
    // - an optional `dispose` function allowing to
    // gracefully close the service;
    // - an optional `fatalErrorPromise` property to
    // handle the service unrecoverable failure.
    type: 'provider',
    singleton: true,
  },
  async ({ CONFIG, DB_URI, log }) => {
    const db = await MongoClient.connect(DB_URI, CONFIG.databaseOptions);
    let fatalErrorPromise = new Promise((resolve, reject) => {
      db.once('error', reject);
    });

    // Logging only if the `log` service is defined
    log && log('info', 'db service initialized!');

    return {
      service: db,
      dispose: db.close.bind(db, true),
      fatalErrorPromise,
    };
  },
);

// Here we are registering our initializer apart to
// be able to reuse it, we also declare the required
// DB_URI constant it needs
$.register(constant('DB_URI', 'posgresql://xxxx'));
$.register(initDB);

// Say we need to use two different DB server
// We can reuse our initializer by tweaking
// some of its properties
$.register(constant('DB_URI2', 'posgresql://yyyy'));
$.register(
  // First we remap the injected dependencies. It will
  // take the `DB_URI2` constant and inject it as
  // `DB_URI`
  inject(
    ['CONFIG', 'DB_URI2>DB_URI', '?log'],
    // Then we override its name to make it
    // available as a different service
    name('db2', initDB),
  ),
);

// A lot of NodeJS functions have some side effects
// declaring them as constants allows you to easily
// mock/monitor/patch it. The `common-services` NPM
// module contains a few useful ones
$.register(constant('now', Date.now.bind(Date)))
  .register(constant('log', console.log.bind(console)))
  .register(constant('exit', process.exit.bind(process)));

// Finally, let's declare an `$autoload` service
// to allow us to load only the initializers needed
// to run the given commands
$.register(
  initializer(
    {
      name: '$autoload',
      type: 'service',
      inject: ['CONFIG', 'ARGS'],
      // Note that the auto loader must be a singleton
      singleton: true,
    },
    async ({ CONFIG, ARGS }) => async (serviceName) => {
      if ('command' !== serviceName) {
        // Allows to signal that the dependency is not found
        // so that optional dependencies doesn't impeach the
        // injector to resolve the dependency tree
        throw new YError('E_UNMATCHED_DEPENDENCY', serviceName);
      }
      try {
        const path = CONFIG.commands + '/' + ARGS[2];
        return {
          path,
          initializer: require(path).default,
        };
      } catch (err) {
        throw new Error(`Cannot load ${serviceName}: ${ARGS[2]}!`);
      }
    },
  ),
);

// At this point, nothing is running. To instanciate the
// services, we have to create an execution silo using
// them. Note that we required the `$instance` service
// implicitly created by `knifecycle`
$.run(['command', '$instance', 'exit', 'log'])
  // Here, command contains the initializer eventually
  // found by automatically loading a NodeJS module
  // in the above `$autoload` service. The db connection
  // will only be instanciated if that command needs it
  .then(async ({ command, $instance, exit, log }) => {
    try {
      command();

      log('It worked!');
    } catch (err) {
      log('It failed!', err);
    } finally {
      // Here we ensure every db connections are closed
      // properly. We could have use `$.destroy()` the same
      // way but this is to illustrate that the Knifecycle
      // instance can be injected in services contexts
      // (rarely done but good to know it exists)
      await $instance.destroy().catch((err) => {
        console.error('Could not exit gracefully:', err);
        exit(1);
      });
    }
  })
  .catch((err) => {
    console.error('Could not launch the app:', err);
    process.exit(1);
  });

Running the following should make the magic happen:

cat "{ commands: './commands'}" > config.json
DEBUG=knifecycle CONFIG_PATH=./config.json node -r @babel/register bin.js mycommand test
// Prints: Could not launch the app: Error: Cannot load command: mycommand!
// (...stack trace)

Or at least, we still have to create commands, let's create the mycommand one:

// commands/mycommand.js
import { initializer } from './dist';

// A simple command that prints the given args
export default initializer(
  {
    name: 'command',
    type: 'service',
    // Here we could have injected whatever we declared
    // in the previous file: db, now, exit...
    inject: ['ARGS', 'log'],
  },
  async ({ ARGS, log }) => {
    return () => log('Command args:', ARGS.slice(2));
  },
);

So now, it works:

DEBUG=knifecycle CONFIG_PATH=./config.json node -r @babel/register bin.js mycommand test
// Prints: Command args: [ 'mycommand', 'test' ]
// It worked!

This is a very simple example but you can find a complexer CLI usage with (metapak)[https://github.com/nfroidure/metapak/blob/master/bin/metapak.js].

Auto detection

Knifecycle also provide some utility function to automatically assign the initializer property declarations, the following 3 ways to declare the getUser service are equivalent:

import noop from 'noop';
import { autoInject, inject, initializer, autoService } from 'knifecycle';

initializer({
  name: 'getUser',
  inject: ['db', '?log'],
  type: 'service',
}, getUser);

service('getUser', autoInject(getUser)));

autoService(getUser);

async function getUser({ db, log = noop}) {}

That said, if you need to build your code with webpack/babel you may have to convert auto-detections to raw declarations with the babel-plugin-knifecycle plugin. You can also do this only for the performance improvements it brings.

Also, keep in mind that the auto-detection is based on a simple regular expression so you should care to keep initializer signatures simple to avoid having a E_AUTO_INJECTION_FAILURE error. As a rule of thumb, avoid setting complex default values.

// Won't work
autoInject(async ({ log = () => {} }) => {});

// Will work
function noop() {}
autoInject(async ({ log = noop }) => {});

Debugging

Simply use the DEBUG environment variable by setting it to 'knifecycle':

DEBUG=knifecycle npm t

The output is very verbose but lead to a deep understanding of mechanisms that take place under the hood.

Plans

The scope of this library won't change. However the plan is:

improve performances;
track bugs ;).

I'll also share most of my own initializers and their stubs/mocks in order to let you reuse it through your projects easily. Here are the current projects that use this DI lib:

common-services: contains the services I use the most in my apps,
memory-kv-store: a simple in memory key-value store,
whook: a framework to build REST web services.
postgresql-service: a simple wrapper around the pg module,
jwt-service: a simple wrapper around the jwt module to simplify its use,
ftp-service: a FTP client with clean defaults.

Notice that those modules remains usable without using Knifecycle at all which is maybe the best feature of this library ;).

API

Classes

Knifecycle

Members

default ⇒ Promise.<function()>: Instantiate the initializer builder service

Functions

reuseSpecialProps(from, to, [amend]) ⇒ function: Apply special props to the given initializer from another one and optionally amend with new special props
constant(name, value) ⇒ function: Decorator that creates an initializer for a constant value
service(serviceBuilder, [name], [dependencies], [singleton], [extra]) ⇒ function: Decorator that creates an initializer from a service builder
autoService(serviceBuilder) ⇒ function: Decorator that creates an initializer from a service builder by automatically detecting its name and dependencies
provider(providerBuilder, [name], [dependencies], [singleton], [extra]) ⇒ function: Decorator that creates an initializer for a provider builder
autoProvider(providerBuilder) ⇒ function: Decorator that creates an initializer from a provider builder by automatically detecting its name and dependencies
wrapInitializer(wrapper, baseInitializer) ⇒ function: Allows to wrap an initializer to add extra initialization steps
inject(dependencies, initializer) ⇒ function: Decorator creating a new initializer with different dependencies declarations set to it.
useInject(from, to) ⇒ function: Apply injected dependencies from the given initializer to another one
mergeInject(from, to) ⇒ function: Merge injected dependencies of the given initializer with another one
autoInject(initializer) ⇒ function: Decorator creating a new initializer with different dependencies declarations set to it according to the given function signature.
alsoInject(dependencies, initializer) ⇒ function: Decorator creating a new initializer with some more dependencies declarations appended to it.
extra(extraInformations, initializer, [merge]) ⇒ function: Decorator creating a new initializer with some extra informations appended to it. It is just a way for user to store some additional informations but has no interaction with the Knifecycle internals.
singleton(initializer, [isSingleton]) ⇒ function: Decorator to set an initializer singleton option.
name(name, initializer) ⇒ function: Decorator to set an initializer name.
autoName(initializer) ⇒ function: Decorator to set an initializer name from its function name.
type(type, initializer) ⇒ function: Decorator to set an initializer type.
initializer(properties, initializer) ⇒ function: Decorator to set an initializer properties.
handler(handlerFunction, [name], [dependencies], [options]) ⇒ function: Shortcut to create an initializer with a simple handler
autoHandler(handlerFunction) ⇒ function: Allows to create an initializer with a simple handler automagically
parseDependencyDeclaration(dependencyDeclaration) ⇒ Object: Explode a dependency declaration an returns its parts.
stringifyDependencyDeclaration(dependencyDeclarationParts) ⇒ String: Stringify a dependency declaration from its parts.
unwrapInitializerProperties(initializer) ⇒ function: Utility function to check and reveal initializer properties.

Knifecycle

Kind: global class

Knifecycle
- new Knifecycle()
- .register(initializer) ⇒ Knifecycle
- .toMermaidGraph(options) ⇒ String
- .run(dependenciesDeclarations) ⇒ Promise
- .destroy() ⇒ Promise
- ._getServiceDescriptor(siloContext, serviceName, options, serviceProvider) ⇒ Promise
- ._initializeServiceDescriptor(siloContext, serviceName, options) ⇒ Promise
- ._initializeDependencies(siloContext, serviceName, servicesDeclarations, options) ⇒ Promise

new Knifecycle()

Create a new Knifecycle instance

Returns: Knifecycle - The Knifecycle instance
Example

import Knifecycle from 'knifecycle'

const $ = new Knifecycle();

knifecycle.register(initializer) ⇒ `Knifecycle`

Kind: instance method of Knifecycle
Returns: Knifecycle - The Knifecycle instance (for chaining)

Param	Type	Description
initializer	`function`	An initializer

knifecycle.toMermaidGraph(options) ⇒ `String`

Outputs a Mermaid compatible dependency graph of the declared services. See Mermaid docs

Kind: instance method of Knifecycle
Returns: String - Returns a string containing the Mermaid dependency graph

Param	Type	Description
options	`Object`	Options for generating the graph (destructured)
options.shapes	`Array.<Object>`	Various shapes to apply
options.styles	`Array.<Object>`	Various styles to apply
options.classes	`Object`	A hash of various classes contents

Example

import Knifecycle, { inject, constant, service } from 'knifecycle';
import appInitializer from './app';

const $ = new Knifecycle();

$.register(constant('ENV', process.env));
$.register(constant('OS', require('os')));
$.register(service('app', inject(['ENV', 'OS'], appInitializer)));
$.toMermaidGraph();

// returns
graph TD
  app-->ENV
  app-->OS

knifecycle.run(dependenciesDeclarations) ⇒ `Promise`

Creates a new execution silo

Kind: instance method of Knifecycle
Returns: Promise - Service descriptor promise

Param	Type	Description
dependenciesDeclarations	`Array.<String>`	Service name.

Example

import Knifecycle, { constant } from 'knifecycle'

const $ = new Knifecycle();

$.register(constant('ENV', process.env));
$.run(['ENV'])
.then(({ ENV }) => {
 // Here goes your code
})

knifecycle.destroy() ⇒ `Promise`

Destroy the Knifecycle instance

Kind: instance method of Knifecycle
Returns: Promise - Full destruction promise
Example

import Knifecycle, { constant } from 'knifecycle'

const $ = new Knifecycle();

$.register(constant('ENV', process.env));
$.run(['ENV'])
.then(({ ENV }) => {
   // Here goes your code

   // Finally destroy the instance
   $.destroy()
})

knifecycle._getServiceDescriptor(siloContext, serviceName, options, serviceProvider) ⇒ `Promise`

Initialize or return a service descriptor

Kind: instance method of Knifecycle
Returns: Promise - Service descriptor promise.

Param	Type	Description
siloContext	`Object`	Current execution silo context
serviceName	`String`	Service name.
options	`Object`	Options for service retrieval
options.injectorContext	`Boolean`	Flag indicating the injection were initiated by the $injector
options.autoloading	`Boolean`	Flag to indicating $autoload dependencies on the fly loading
serviceProvider	`String`	Service provider.

knifecycle._initializeServiceDescriptor(siloContext, serviceName, options) ⇒ `Promise`

Initialize a service descriptor

Kind: instance method of Knifecycle
Returns: Promise - Service dependencies hash promise.

Param	Type	Description
siloContext	`Object`	Current execution silo context
serviceName	`String`	Service name.
options	`Object`	Options for service retrieval
options.injectorContext	`Boolean`	Flag indicating the injection were initiated by the $injector
options.autoloading	`Boolean`	Flag to indicating $autoload dependendencies on the fly loading.

knifecycle._initializeDependencies(siloContext, serviceName, servicesDeclarations, options) ⇒ `Promise`

Initialize a service dependencies

Kind: instance method of Knifecycle
Returns: Promise - Service dependencies hash promise.

Param	Type	Description
siloContext	`Object`	Current execution silo siloContext
serviceName	`String`	Service name.
servicesDeclarations	`String`	Dependencies declarations.
options	`Object`	Options for service retrieval
options.injectorContext	`Boolean`	Flag indicating the injection were initiated by the $injector
options.autoloading	`Boolean`	Flag to indicating $autoload dependendencies on the fly loading.

default ⇒ `Promise.<function()>`

Instantiate the initializer builder service

Kind: global variable
Returns: Promise.<function()> - A promise of the buildInitializer function

Param	Type	Description
services	`Object`	The services to inject
services.$autoload	`Object`	The dependencies autoloader

Example

import initInitializerBuilder from 'knifecycle/dist/build';

const buildInitializer = await initInitializerBuilder({
  $autoload: async () => {},
});

reuseSpecialProps(from, to, [amend]) ⇒ `function`

Apply special props to the given initializer from another one and optionally amend with new special props

Kind: global function
Returns: function - The newly built initializer

Param	Type	Default	Description
from	`function`		The initializer in which to pick the props
to	`function`		The initializer from which to build the new one
[amend]	`Object`	`{}`	Some properties to override

constant(name, value) ⇒ `function`

Decorator that creates an initializer for a constant value

Kind: global function
Returns: function - Returns a new constant initializer

Param	Type	Description
name	`String`	The constant's name.
value	`any`	The constant's value

Example

import Knifecycle, { constant, service } from 'knifecycle';

const { printAnswer } = new Knifecycle()
  .register(constant('THE_NUMBER', value))
  .register(constant('log', console.log.bind(console)))
  .register(service(
    async ({ THE_NUMBER, log }) => () => log(THE_NUMBER),
    'printAnswer',
    ['THE_NUMBER', 'log'],
  ))
  .run(['printAnswer']);

printAnswer(); // 42

service(serviceBuilder, [name], [dependencies], [singleton], [extra]) ⇒ `function`

Decorator that creates an initializer from a service builder

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
serviceBuilder	`function`	An async function to build the service
[name]	`String`	The service's name
[dependencies]	`Array.<String>`	The service's injected dependencies
[singleton]	`Boolean`	Whether the service is a singleton or not
[extra]	`any`	Eventual extra informations

Example

import Knifecycle, { constant, service } from 'knifecycle';

const { printAnswer } = new Knifecycle()
  .register(constant('THE_NUMBER', value))
  .register(constant('log', console.log.bind(console)))
  .register(service(
    async ({ THE_NUMBER, log }) => () => log(THE_NUMBER),
    'printAnswer',
    ['THE_NUMBER', 'log'],
    true
  ))
  .run(['printAnswer']);

printAnswer(); // 42

autoService(serviceBuilder) ⇒ `function`

Decorator that creates an initializer from a service builder by automatically detecting its name and dependencies

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
serviceBuilder	`function`	An async function to build the service

provider(providerBuilder, [name], [dependencies], [singleton], [extra]) ⇒ `function`

Decorator that creates an initializer for a provider builder

Kind: global function
Returns: function - Returns a new provider initializer

Param	Type	Description
providerBuilder	`function`	An async function to build the service provider
[name]	`String`	The service's name
[dependencies]	`Array.<String>`	The service's dependencies
[singleton]	`Boolean`	Whether the service is a singleton or not
[extra]	`any`	Eventual extra informations

Example

import Knifecycle, { provider } from 'knifecycle'
import fs from 'fs';

const $ = new Knifecycle();

$.register(provider(configProvider, 'config'));

async function configProvider() {
  return new Promise((resolve, reject) {
    fs.readFile('config.js', function(err, data) {
      let config;

      if(err) {
        reject(err);
        return;
      }

      try {
        config = JSON.parse(data.toString);
      } catch (err) {
        reject(err);
        return;
      }

      resolve({
        service: config,
      });
    });
  });
}

autoProvider(providerBuilder) ⇒ `function`

Decorator that creates an initializer from a provider builder by automatically detecting its name and dependencies

Kind: global function
Returns: function - Returns a new provider initializer

Param	Type	Description
providerBuilder	`function`	An async function to build the service provider

wrapInitializer(wrapper, baseInitializer) ⇒ `function`

Allows to wrap an initializer to add extra initialization steps

Kind: global function
Returns: function - The new initializer

Param	Type	Description
wrapper	`function`	A function taking dependencies and the base service in arguments
baseInitializer	`function`	The initializer to decorate

inject(dependencies, initializer) ⇒ `function`

Decorator creating a new initializer with different dependencies declarations set to it.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
dependencies	`Array.<String>`	List of dependencies declarations to declare which services the initializer needs to provide its own service
initializer	`function`	The initializer to tweak

Example

import Knifecycle, { inject } from 'knifecycle'
import myServiceInitializer from './service';

new Knifecycle()
 .register(
   service(
     inject(['ENV'], myServiceInitializer)
     'myService',
   )
  )
);

useInject(from, to) ⇒ `function`

Apply injected dependencies from the given initializer to another one

Kind: global function
Returns: function - The newly built initialization function

Param	Type	Description
from	`function`	The initialization function in which to pick the dependencies
to	`function`	The destination initialization function

mergeInject(from, to) ⇒ `function`

Merge injected dependencies of the given initializer with another one

Kind: global function
Returns: function - The newly built initialization function

Param	Type	Description
from	`function`	The initialization function in which to pick the dependencies
to	`function`	The destination initialization function

autoInject(initializer) ⇒ `function`

Decorator creating a new initializer with different dependencies declarations set to it according to the given function signature.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
initializer	`function`	The original initializer

Example

import Knifecycle, { autoInject, name } from 'knifecycle'

new Knifecycle()
  .register(
    name(
      'application',
      autoInject(
        async ({ NODE_ENV, mysql: db }) =>
          async () => db.query('SELECT applicationId FROM applications WHERE environment=?', [NODE_ENV])
        )
      )
    )
  )
);

alsoInject(dependencies, initializer) ⇒ `function`

Decorator creating a new initializer with some more dependencies declarations appended to it.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
dependencies	`Array.<String>`	List of dependencies declarations to append
initializer	`function`	The initializer to tweak

Example

import Knifecycle, { alsoInject } from 'knifecycle'
import myServiceInitializer from './service';

new Knifecycle()
.register(service(
  alsoInject(['ENV'], myServiceInitializer),
  'myService',
));

extra(extraInformations, initializer, [merge]) ⇒ `function`

Decorator creating a new initializer with some extra informations appended to it. It is just a way for user to store some additional informations but has no interaction with the Knifecycle internals.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Default	Description
extraInformations	`Object`		An object containing those extra informations.
initializer	`function`		The initializer to tweak
[merge]	`Boolean`	`false`	Whether the extra object should be merged with the existing one or not

Example

import Knifecycle, { extra } from 'knifecycle'
import myServiceInitializer from './service';

new Knifecycle()
.register(service(
  extra({ httpHandler: true }, myServiceInitializer),
  'myService',
));

singleton(initializer, [isSingleton]) ⇒ `function`

Decorator to set an initializer singleton option.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Default	Description
initializer	`function`		The initializer to tweak
[isSingleton]	`boolean`	`true`	Define the initializer singleton option (one instance for several runs if true)

Example

import Knifecycle, { inject, singleton } from 'knifecycle';
import myServiceInitializer from './service';

new Knifecycle()
.register(service(
  inject(['ENV'],
    singleton(myServiceInitializer)
  ),
  'myService',
));

name(name, initializer) ⇒ `function`

Decorator to set an initializer name.

Kind: global function
Returns: function - Returns a new initializer with that name set

Param	Type	Description
name	`String`	The name of the service the initializer resolves to.
initializer	`function`	The initializer to tweak

Example

import Knifecycle, { name } from 'knifecycle';
import myServiceInitializer from './service';

new Knifecycle()
.register(name('myService', myServiceInitializer));

autoName(initializer) ⇒ `function`

Decorator to set an initializer name from its function name.

Kind: global function
Returns: function - Returns a new initializer with that name set

Param	Type	Description
initializer	`function`	The initializer to name

Example

import Knifecycle, { autoName } from 'knifecycle';

new Knifecycle()
.register(autoName(async function myService() {}));

type(type, initializer) ⇒ `function`

Decorator to set an initializer type.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
type	`String`	The type to set to the initializer.
initializer	`function`	The initializer to tweak

Example

import Knifecycle, { name, type } from 'knifecycle';
import myServiceInitializer from './service';

new Knifecycle()
.register(
  type('service',
    name('myService',
      myServiceInitializer
    )
  )
);

initializer(properties, initializer) ⇒ `function`

Decorator to set an initializer properties.

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
properties	`Object`	Properties to set to the service.
initializer	`function`	The initializer to tweak

Example

import Knifecycle, { initializer } from 'knifecycle';
import myServiceInitializer from './service';

new Knifecycle()
.register(initializer({
  name: 'myService',
  type: 'service',
  inject: ['ENV'],
  singleton: true,
}, myServiceInitializer));

handler(handlerFunction, [name], [dependencies], [options]) ⇒ `function`

Shortcut to create an initializer with a simple handler

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Default	Description
handlerFunction	`function`		The handler function
[name]	`String`		The name of the handler. Default to the DI prop if exists
[dependencies]	`Array.<String>`	`[]`	The dependencies to inject in it
[options]	`Object`		Options attached to the built initializer

Example

import Knifecycle, { handler } from 'knifecycle';

new Knifecycle()
.register(handler(getUser, 'getUser', ['db', '?log']));

const QUERY = `SELECT * FROM users WHERE id=$1`
async function getUser({ db }, userId) {
  const [row] = await db.query(QUERY, userId);

  return row;
}

autoHandler(handlerFunction) ⇒ `function`

Allows to create an initializer with a simple handler automagically

Kind: global function
Returns: function - Returns a new initializer

Param	Type	Description
handlerFunction	`function`	The handler function

Example

import Knifecycle, { autoHandler } from 'knifecycle';

new Knifecycle()
.register(autoHandler(getUser));

const QUERY = `SELECT * FROM users WHERE id=$1`
async function getUser({ db }, userId) {
  const [row] = await db.query(QUERY, userId);

  return row;
}

parseDependencyDeclaration(dependencyDeclaration) ⇒ `Object`

Explode a dependency declaration an returns its parts.

Kind: global function
Returns: Object - The various parts of it

Param	Type	Description
dependencyDeclaration	`String`	A dependency declaration string

Example

parseDependencyDeclaration('pgsql>db');
// Returns
{
  serviceName: 'pgsql',
  mappedName: 'db',
  optional: false,
}

stringifyDependencyDeclaration(dependencyDeclarationParts) ⇒ `String`

Stringify a dependency declaration from its parts.

Kind: global function
Returns: String - The various parts of it

Param	Type	Description
dependencyDeclarationParts	`Object`	A dependency declaration string

Example

stringifyDependencyDeclaration({
  serviceName: 'pgsql',
  mappedName: 'db',
  optional: false,
});

// Returns
'pgsql>db'

unwrapInitializerProperties(initializer) ⇒ `function`

Utility function to check and reveal initializer properties.

Kind: global function
Returns: function - Returns revealed initializer (with TypeScript types for properties)

Param	Type	Description
initializer	`function`	The initializer to tweak

Authors

Nicolas Froidure

License

MIT

Usage no npm install needed!

README

knifecycle

Features

Usage

Auto detection

Debugging

Plans

API

Classes

Members

Functions

Knifecycle

new Knifecycle()

knifecycle.register(initializer) ⇒ Knifecycle

knifecycle.toMermaidGraph(options) ⇒ String

knifecycle.run(dependenciesDeclarations) ⇒ Promise

knifecycle.destroy() ⇒ Promise

knifecycle._getServiceDescriptor(siloContext, serviceName, options, serviceProvider) ⇒ Promise

knifecycle._initializeServiceDescriptor(siloContext, serviceName, options) ⇒ Promise

knifecycle._initializeDependencies(siloContext, serviceName, servicesDeclarations, options) ⇒ Promise

default ⇒ Promise.<function()>

reuseSpecialProps(from, to, [amend]) ⇒ function

constant(name, value) ⇒ function

service(serviceBuilder, [name], [dependencies], [singleton], [extra]) ⇒ function

autoService(serviceBuilder) ⇒ function

provider(providerBuilder, [name], [dependencies], [singleton], [extra]) ⇒ function

autoProvider(providerBuilder) ⇒ function

wrapInitializer(wrapper, baseInitializer) ⇒ function

inject(dependencies, initializer) ⇒ function

useInject(from, to) ⇒ function

mergeInject(from, to) ⇒ function

autoInject(initializer) ⇒ function

alsoInject(dependencies, initializer) ⇒ function

extra(extraInformations, initializer, [merge]) ⇒ function

singleton(initializer, [isSingleton]) ⇒ function

name(name, initializer) ⇒ function

autoName(initializer) ⇒ function

type(type, initializer) ⇒ function

initializer(properties, initializer) ⇒ function

handler(handlerFunction, [name], [dependencies], [options]) ⇒ function

autoHandler(handlerFunction) ⇒ function

parseDependencyDeclaration(dependencyDeclaration) ⇒ Object

stringifyDependencyDeclaration(dependencyDeclarationParts) ⇒ String

unwrapInitializerProperties(initializer) ⇒ function

Authors

License

knifecycle.register(initializer) ⇒ `Knifecycle`

knifecycle.toMermaidGraph(options) ⇒ `String`

knifecycle.run(dependenciesDeclarations) ⇒ `Promise`

knifecycle.destroy() ⇒ `Promise`

knifecycle._getServiceDescriptor(siloContext, serviceName, options, serviceProvider) ⇒ `Promise`

knifecycle._initializeServiceDescriptor(siloContext, serviceName, options) ⇒ `Promise`

knifecycle._initializeDependencies(siloContext, serviceName, servicesDeclarations, options) ⇒ `Promise`

default ⇒ `Promise.<function()>`

reuseSpecialProps(from, to, [amend]) ⇒ `function`

constant(name, value) ⇒ `function`

service(serviceBuilder, [name], [dependencies], [singleton], [extra]) ⇒ `function`

autoService(serviceBuilder) ⇒ `function`

provider(providerBuilder, [name], [dependencies], [singleton], [extra]) ⇒ `function`

autoProvider(providerBuilder) ⇒ `function`

wrapInitializer(wrapper, baseInitializer) ⇒ `function`

inject(dependencies, initializer) ⇒ `function`

useInject(from, to) ⇒ `function`

mergeInject(from, to) ⇒ `function`

autoInject(initializer) ⇒ `function`

alsoInject(dependencies, initializer) ⇒ `function`

extra(extraInformations, initializer, [merge]) ⇒ `function`

singleton(initializer, [isSingleton]) ⇒ `function`

name(name, initializer) ⇒ `function`

autoName(initializer) ⇒ `function`

type(type, initializer) ⇒ `function`

initializer(properties, initializer) ⇒ `function`

handler(handlerFunction, [name], [dependencies], [options]) ⇒ `function`

autoHandler(handlerFunction) ⇒ `function`

parseDependencyDeclaration(dependencyDeclaration) ⇒ `Object`

stringifyDependencyDeclaration(dependencyDeclarationParts) ⇒ `String`

unwrapInitializerProperties(initializer) ⇒ `function`