len

Calendar database for resource bookings using leveldb

installation

$ npm install len

usage

You create a len database by passing in an existing leveldb - this can also be a sub-level

var len = require('len');
var level = require('level');
 
// create a new leveldb - this can also be a sub-level
var leveldb = level('/tmp/lentest');
 
// create a new lem store using the leveldb
var lendb = len(db);

A booking represents a resource being used for a period of time.

Here we create a booking for bob the mechanic:

 
// start at 9.30
var start = new Date('04/03/14 09:30:00');
// end at 13.30
var end = new Date('04/03/14 13:30:00');
 
lendb.saveBooking('mechanics.bob', {
    id:14, 
    start:start,
    end:end,
    meta:{
        name:'Fix Car',
        customer:34
    }
}, function(error, booking){
 
    // bob is all booked in
 
})

We can ask len about bookings for all mechanics in a particular month:

var through = require('through');
var start = new Date('03/01/2014');
var end = new Date('04/01/2014').getTime();
 
var bookings_in_month = 0;
 
lendb.createBookingStream('mechanics', {
    start:start,
    end:end,
    // this means booking must start and end inside the window
    inclusive:true
}).pipe(through(function(booking){
 
    // booking is an object with 'id', 'start', 'end' and 'meta' keys
    bookings_in_month++;
    
}, function(){
    console.log('there are: ' + bookings_in_month.length + ' mechanic bookings in March');
 
}))

resource tree

Resources are created using paths and this can be a useful way to get booking reports at various layers.

For example - imagine we have a team that does some projects - we want to be able to ask the following questions:

• the start and end point of one project
• an array of bookings for one project
• an array of bookings for all projects
• an array of bookings between certain points for all projects

This can be done using the paths you give to resources - if we create resources with the following paths:

• team.alpha.project.1
• team.alpha.project.2

queries

Then we can ask for the start and end for one project:

lendb.getRange('team.alpha.project.1', function(err, bounds){
    // bounds.start = timestamp of the earliest start of booking for the project
    // bounds.end = timestamp of the latest end of booking for the project
})

get a readstream of bookings:

// bookings for one project
lendb.createBookingStream('team.alpha.project.1').pipe(through(function(booking){
    // booking is an object
}))
 
// bookings for one team's projects
lendb.createBookingStream('team.alpha.project')

get a readstream of bookings withing a time period

var start = new Date('03/04/14 09:30:00');
var end = new Date('03/04/14 13:30:00');
 
lendb.createBookingStream('team.alpha.project', {
    start:start,
    end:end
})

api

len(leveldb);

Create a new len database from the provided leveldb. This can be a level-sublevel so you can partition len into an existing database.

var len = require('len');
var level = require('level');
 
var leveldb = level('/tmp/mylem');
var lendb = len(leveldb);

lendb.loadBooking(resourcepath, bookingid, callback)

Fetch a booking record using the resourcepath and booking id:

lendb.loadBooking('project.1', 14, function(err, booking){
 
    // booking is an object with 'id', 'start', 'end' and 'meta' keys
 
})

lendb.saveBooking(resourcepath, booking, callback)

Insert/update a booking into the schedule for a resource.

booking is an object:

{
    id: 0,                   // the id of the booking you are saving - this is auto-created is left blank
    start: Date(),           // the start timestamp of the booking
    end: Date(),             // the end timestamp of the booking
    meta: {                  // an object with anything you like for the booking meta-data
        customer:12,
        comments:'apples'
    }
}

The start and end timestamps are required - the meta object is converted to a JSON string and is returned in the 'meta' property of bookings.

var start = new Date('03/04/14 09:30:00');
var end = new Date('03/04/14 13:30:00');
 
lendb.createBooking('project.1', {
    id:14,
    start:start,
    end:end,
    meta:{
        name:'meta data here'
    }
}, function(err){
 
    // the booking is created for the resource
 
})

lendb.removeBooking(resourcepath, bookingid, callback)

Remove a booking from the schedule

resource.removeBooking('project.1', 14, function(err){
 
    // the booking is removed
 
})

lendb.getRange(resourcepath, [window], callback)

Use this to get the start and end date for bookings in a resource

lendb.getRange('projects.1', function(err, range){
    // range.start and range.end are timestamps
})

You can also pass a window to constrain the results:

lendb.getRange('projects.1', {
    start:start,
    end:end
}, function(err, range){
 
    // range.start and range.end are timestamps
 
})

lendb.createBookingStream(resourcepath, [window], callback)

Use this to get an object stream of bookings for a given resource.

var through = require('through');
 
lendb.createBookingStream('mechanics.bob', {
    start:start,
    end:end
}).pipe(through(function(booking){
 
    console.log('booking found');
    console.log(booking.id);
    
}))

You can also query the booking stream using a time-window:

var through = require('through');
var start = new Date('03/01/2014');
var end = new Date('04/01/2014').getTime();
 
var bookings_in_month = 0;
 
lendb.createBookingStream('mechanics.bob', {
    start:start,
    end:end,
    inclusive:true
}).pipe(through(function(booking){
 
    // booking is an object with 'id', 'start', 'end' and 'meta' keys
    bookings_in_month++;
    
}, function(){
    console.log('there are: ' + bookings_in_month.length + ' bookings for bob in March');
 
}))

the inclusive option controls whether bookings have to start and end inside the time window (true) or if any part of it is in the time window (false)

license

MIT