require-yml

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Why

It's instead of require-yaml because of this reason.

And, it can require a yml/yaml/json file/whole directory, or with iterator, or use async callback.

Install

npm install require-yml

Breaking changes in 2.0.0

• version 1.x defaults to suppresses load/parse errors, version 2.x defaults to throw them.
• v1.4.x and v2.x let you provide your own error handlers: restore original behavior by providing your own onLoadError as an empty function.

Usage

configs directory:

configs/
  |- foo/
    |- bar/
      |- a.yml
      |- b.yaml
      |- c.json
    |- empty/

const req = require('require-yml')

require a file (yml/yaml/json)

const yml = req('./configs/foo/bar/a.yml')
const yaml = req('./configs/foo/bar/b')  // b.yaml
const json = req('./configs/foo/bar/c.json')
console.log(yml, yaml, json)
// >> {}, {}, {}

require a directory

const all = req('./configs')
console.log(all)
// >> json object {"foo":{"bar":[Object Object]}

• All files in the directory are required, as properties of an object.
• By default, the file base name as it appears on the OS is used as property name in the returned object.

an empty file/directory returns undefined

const empty = req('./configs/empty')
console.log(empty)
// >> undefined

require an explicit list of files, the later merges into the former and cascades

const yml = req(['./config/default.yml', './configs/local.yml'])

• having directories in these names will cause an error you should handle. We don't know of such use-case, but if you ever encounter one - you may provide your own loaders for the pattern /\.yml$/ - see below)

require a list of files, the later cascades, but let the tool guess extensions

const yml = req(['./config/default', './configs/local'])

Notes:

• by default, tool tries extensions by this order: .js, .yml, .yaml, .json, / (dir) All found are merged on each other, the later cascades.
• the built-in .js first - gives you more power allowing to start with a type that is not native to json or safe-mode yaml, e.g:

  //file: config/strategies/cli-banner.js
  module.export = function CliBanner() { }
    CliBanner.prototype.text = '@TITLE'
  CliBanner.prototype.header = function(title) { return this.text.replace(/@TITLE/, title) }

  #file: config/strategies/cli-banner.yaml
  CliBanner:
  prototype:
    text: |
      -----------------------
      |     @TITLE          |
      -----------------------

require a list of files with unspecified endings, but you control what extensions to try and in what order

const yml = req({ 
  targets: ['./config/default', './configs/local'],
  extensions: [ '.json', '.yaml' ]
})

• this results in try the load order below, where each stage treats it's previous as defaults and cascades it with it's own values, whenever such are found:
  • file: ./config/default.json
  • file:./config/default.yaml
  • directory: ./config/default/
  • file: ./config/local.json
  • file: ./config/local.yaml
  • directory: ./config/local/
• Note: Mind the difference between loading a list of files and loading a directory:
  • list of files - merges the later into the former, the later cascades.
  • directory - uses by default file base-names as property names, where files of same name and different extensions are basically a list of files.

Provide your own logic to map files to property names

const path = require('path')
const camelCase = require('lodash/camelCase')
const yml = req({
  target: './config',
  fileToProp: file => camelCase(path.baseName(file))
})

• file provided to fileToProp is a full absolute path as it appears on your OS
• what fileToProp(file) returns is used as property name
• if there is already a value there - it is merged into and cascaded by the current.
• Note: targets is a synonym for target for readability . Each can be provided as a string or as an array of strings. If you provide both - target is used, targets is ignored. When it's provided as a string - it's understood as a list of files with a single-element.

Provide your own custom loaders

const fs = require('fs')
const jsonc = require('jsonc')
const yml = req({
  targets: ['./config/default', './configs/local'],
  loaders: [{ 
    pattern: /.jsonc?$/, //<-- this will match .json and .jsonc alike
    load: target => jsonc.parse(fs.readFileSync(target)),
  }]

Notes:

• user loaders precede built-in ones. Loader of first matched pattern is used. The built-in loaders are:

    { pattern: /\.(yml|yaml)$/, load: target => jsYaml.load(fs.readFileSync(resolvePath(target), 'utf8')) },
    { pattern: /\.(json|js)$/, load: target => require(resolvePath(target)) },

• order of loaders does not effect order of loaded files (order of extensions does, and only between files in same directory)
• You can support custom extensions by providing loaders
• You can have the tool try your custom extensions for paths you provide without extension by including it in extensions

apply a custom mapper to each loaded file

const mapper = function(json) {
  json.inject = 'everywhere'
  return json
}
// v >= 2.0
const yml2 = req({ target: './configs', mapper })
console.log(yml2.foo.bar.a.inject)
// >> 'everywhere'

// legacy form (supported for backward compatibility)
const yml1 = req('./configs', mapper)
console.log(yml1.foo.bar.a.inject)

• mapper iterator is called for every value that is loaded before being added to the value tree.
• use mappers to map or mutate loaded values.
• suppress loaded values by returning a falsy value.

handle require or mapper errors

const yml = req({
  target: './configs',
  mapper: function broken(json) { 
    a = b // -> throws `a is undefined`
  },
  onLoadError: err => {
    // handle your errors here
    switch(e.CODE) {
      ...
    }
  },
})

or use the global hook:

req.onLoadError = function(err) {
  // handle your errors here
  switch(e.CODE) {
    ...
  }
}

async require

req('./configs', null, function(yml){
  console.log(yml.foo.bar.a)
})
// >> {}

Note: operation is pseudo async. Nothing happens in parallel, but the loading happens on next tick after your code has ran and all your declarations are made.

Test

npm test

Test outputs numbered test cases. Numbered test-cases can be used to filter ran tests.

node test 15,18

will run only cases 15,18.

License

MIT