set-property-from-file

Set object property using a file path and contents

var setPropertyFromFile = require('set-property-from-file');

// foo.txt (Hello!)

setPropertyFromFile({bar: true}, 'foo.txt', 'utf8', function(err, res) {
  if (err) {
    throw err;
  }

  res; //=> {foo: 'Hello!', bar: true};
});

Installation

Use npm.

npm install set-property-from-file

API

var setPropertyFromFile = require('set-property-from-file');

setPropertyFromFile(target, filePath [, options], callback)

target: Object
filePath: String (a relative file path)
options: Object or String (file encoding)
callback: Function

It reads a file asynchronously, then sets the property of the target object to the file contents. (It automatically strip UTF-8 byte order mark from contents.)

The names of the created properties are based on the file path. For example,

• foo.txt sets foo property.
• foo/bar.txt sets foo.bar property.
• foo/bar/baz.qux.txt sets foo.bar['baz.qux'] property.
• ../foo/bar.txt sets ['..'].foo.bar property.
• foo/../bar/baz.txt sets bar.baz property.

var assert = require('assert');
var setPropertyFromFile = require('set-property-from-file');

var target = {
  fixtures: {
    foo: 'bar'
  }
};

setPropertyFromFile(target, 'fixtures/images/00.jpg', function(err, res) {
  if (err) {
    throw err;
  }
  
  // Adds fixtures.images['00'] property to the target object.
  assert.deepEqual(res, {
    fixtures: {
      foo: 'bar' // target's default property
      images: {
        '00': <Buffer ... > // new property
      }
    }
  });
});

It doesn't create a new property under the existing property if the existing property is not an object.

var assert = require('assert');
var setPropertyFromFile = require('set-property-from-file');

var target = {
  fixtures: {
    foo: 'Hello!' // string (not an object)
  }
};

setPropertyFromFile(target, 'fixtures/foo/bar/baz.txt', function(err, res) {
  if (err) {
    throw err;
  }

  // Doesn't overwrite the existing non-object property.
  assert.deepEqual(res, {
    fixtures: {
      foo: 'Hello!' // object['fixtures']['foo'] already exists
    }
  });
});

options

(In addition to the follwing options, all fs.readFile options are available.)

options.cwd

Type: String
Default: process.cwd()

Specify the working directory the source path is relative to. This won't be included in the property names.

// Reads one/two/three.txt
setPropertyFromFile({}, 'two/three.txt', {cwd: 'one'}, function(err, res) {
  res; // {two: {three: <Buffer ...>}}
});

options.base

Type: String
Default: ''

Specify the directory relative to the cwd. This won't be included in the property names.

// Reads one/two/three.txt
setPropertyFromFile({}, 'one/two/three.txt', {base: 'one/two'}, function(err, res) {
  res; // {three: <Buffer ...>}
});

options.ext

Type: Boolean
Default: false

By default the property names don't include file extension. true keeps it in the last property name.

setPropertyFromFile({}, 'index.js', function(err, res) {
  res; //=> {index: ... }
});

setPropertyFromFile({}, 'index.js', {ext: true}, function(err, res) {
  res; //=> {index: {js: ... }}
});

options.processor

Type: Function
Default: undefined

Specify a function to process file contents before setting the properties.

// foo.txt (abcde)

var encoder = function(content) {
  return content.toString().toUpperCase();
};

setPropertyFromFile({}, 'foo.txt', {encoding: encoder}, function(err, res) {
  res; //=> 'ABCDE'
});

callback(error, result)

error: Error if it fails to read the file, otherwise null
result: Object (Target object modified)

Note that it overwrites the target object.

var target = {foo: true};

setPropertyFromFile(target, 'bar.txt', function(err, res) {
  res; //=> {foo: true, bar: ... }
  target; //=> {foo: true, bar: ... }
  res === target; //=> true
});

License

Copyright (c) 2014 Shinnosuke Watanabe

Licensed under the MIT License.