contexter

Reactively extract all available data from files in a directory to one javascript object

Contexter reactively builds a context object from the data and metadata available in files in a directory for easy manipulation. It mirrors the directory structure and selectively extracts data depending on file type. Watches for any change in directory to keep the javascript object continuously updated

It's functionality could be extended by plugins

(You may prefer to start a contexter test drive with contexter-cli sample application)

Usage

Sample dir structure:

dir/
|-- assets/
|   |-- photo.jpg
|   |-- style.css
|   `-- posts.yml   <--- contains foo:"bar"
|
|-- index.html
|-- README.md
`-- notes.txt

In your code:

var Contexter = require('contexter');
 
var ctxr = new Contexter();
 
ctxr.watcher('./dir')
  .on('ready', function (context) {
    console.log( context.dir.assets['posts.yml'].data.foo );
  });

output:

> "bar" // value `foo:"bar"` from inside `posts.yml` 
> "BAZ" // ... value after editing to `foo:"BAZ"` in `posts.yml` 
> ...   // reactively display any update to files in `./dir` 

The result is a reactive context variable equivalent to:

var context = {
              dir: {
                    assets: {
                          "posts.yml": {
                                data: {foo: "bar", ...}, ...
                          }}
                    },
              datafiles: [
                    {...}   // posts.yml
                    ],
              unknowns: [
                    ]      // empty
            }

• The directory structure is mirrored in property dir with all data files, it's data and metadata directly available
• For extra convenience...
  • All data files are also available as an array in sibling property datafiles
  • Files with extension like data files but not able to be processed, are available in an array in next sibling property unknowns

Description

There are two file types. Files with extensions .json, .yml and .ymal are datafile type and those that can not be processed are unknown type

Each datafile appears twice in context object

1. Under the property dir in the corresponding nested level according with the directory structure
2. Under the corresponding file type property. Either datafiles or unknowns

In the context object, a file is represented by a property named after the filename including the extension. For example: file posts.yml is the property "posts.yml" of the object assets

The file value is an object that contains a property (among others) named data with the data values of the parsed content of the file.

This file object also has other properties representing metadata about the file, properties like path and stats

file properties samples:

• .path.full: Full path file
• .path.relative: file path relative to directory provided
• .path.processRelative: file path relative to process.cwd()
• ...and all path properties from upath.parse() function from the npm upath
• ...also, all stats properties from fs.statSync() from the npm fs-extra

Configuration and options

1. For Contexter(config)
2. For .watcher(path, options)

config: Object for Contexter(config) configuration

• config.reportInterval: Number representing the interval milliseconds to report the remaining files to context be ready. Commonly used to keep the user informed that files are been processed. Affects contexting and all events. Default to 0 (zero) meaning that reporting is disabled.
• config.isWatchAll: Boolean to set file watch mode. There are two mode: true for "dir path" and false for "glob optimized". The first one, watch for ALL files in the directory specified, the later one, optimize a glob to watch ONLY for files with their extensions stated in the plugins. Default to false, meaning: "glob optimized" to ONLY watch for a "narrow" set of files
• config.pluginConfig: Object with global plugin configuration (see API below)

options: Object for .watcher(path, options)

• All chokidar.watch() options pass directly to underlying chokidar.watch()

context object format (and content)

The context object format and content can be custom redefined

• Custom file types could be extended beyond the datafile default type, example: image, stylesheet,... (see Advanced Methods below)

• Custom file processes could be used beyond data file JSON and yaml parse, example: other parsers and renders (see Advanced Methods below)

Getting started

Install with npm:

$ npm install contexter --save

Then require and use it in your code:

const Contexter= require('contexter')
 
const ctxr = new Contexter()
 
// Example of a typical implementation structure:
 
// Initialize watcher.
var sentinel = ctxr.watcher('path-to-dir', {
  ignored: /(^|[\/\\])\../ // ignore dot files (filename beginning with a dot)
});
 
// Something to use when events are received.
var log = console.log.bind(console);
 
// Add event listeners.
sentinel
  .on('ready', context => log(`context is ready with ${context.datafiles.length} datafiles`))
 
// More possible events.
sentinel
  .on('started', context => log(`Just started with context empty ${context['/']}`))
  .on('adding', file => log(`File ${file.path.relative} has been added`))
  .on('updating', file => log(`File ${file.path.relative} has been updated`))
  .on('deleting', file => log(`File ${file.path.relative} has been deleted`))
  .on('contexting', files => log(`Processing : ${files.length} files`))
 

(You may prefer to start a contexter test drive with contexter-cli sample application)

API

Contexter([config])

• reportInterval: Time in milliseconds between "remaining files" report (0 to disable reporting)
• isWatchAll: Flag to watch all files. Default to not watch all (false means, optimize)
• pluginConfig: Object with global plugin's configuration
  • pluginConfig.targetDir: Full directory path where file should be render or written

example:

var Contexter = require('contexter');
 
var ctxr = new Contexter({
  reportInterval: 2000 // Report remaining files every 2 sec. until all are contexted
});
 
ctxr.watcher('./dir')
  .on('ready', function (context) {
    console.log( context.dir.assets['posts.yml'].data.foo );
  });

ctxr.watcher(path, [options])

• path (string). Path to dir to be watched recursively
• options (object)
  • All options from chokidar.watch() are passed directly

Events

ctxr.watcher() produces an instance of event-emitter:

• .on(event, callback): Listen for an FS event. Available events:

  • strarting event signature: .on('strarting', callback(context))
  • contexting event signature: .on('contexting', callback(files))
  • ready event signature: .on('ready', callback(context))
  • adding event signature: .on('adding', callback(file))
  • updating event signature: .on('updating', callback(file))
  • deleting event signature: .on('deleting', callback(file))

Additionally all event is available which gets emitted with the underlying event name for every event except starting. It acts as single event triggered by all other events

• all event signature: .on('all', callback(ctx, eventName, payload))
  • payload is an array of files for contexting
  • payload is null for ready
  • payload is a single file for adding, updating and deleting

Advanced Methods

The default file class has 3 types of methods

1. Core: Methods common to all file objects
2. Filetype: Methods that could be replaced by filetype object to "extend" file capabilities like the content and format of the context object to suit datafile or custom file types like image, stylesheet, etc.
3. Plugin: Methods that could be replaced by plugin object to "use" different file process like different parsers or to custom render results from the parsed files

.extend(filetypeName, filetype): Extends the File class to have other file types beyond datafiles or even modify the context object structure and format

• filetypeName: String used as a reference for the filetype object inside plugins
• filetype: Object with methods that replace the some of the original file class methods. Used to define de context format

.use(plugin): Extend the File class to have other file process beyond data file JSON and yaml parse. Custom processes like parse() and render()

• plugin: Object with methods that replace some of the original file class methods

For more on advanced methods, see overview and detailed information

Acknowledgements

• @zeke Thanks for your ideas, code and time

License

The MIT License (MIT)

Copyright (c) 2017 Eduardo Martinez

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.