multiwayDB

Overview

in-memory database loaded from a JSON file and allows all CRUD operations simultaneously via REST or direct API, plus using the direct API over REST.

This is not intended for production use; at least the author never does. I use it primarily to test data points. I will load the data in on one end, have my app being tested use the REST API, and then validate the data from directly within the database.

Changes

Please see at the end of this README for any breaking changes.

Installation

npm install multiwaydb
	

Instantiation

Require it, initialize it and listen for connections:

var db = require('multiwaydb');

db.init(pathToJsonFile); // initialize the database with data from path
	
	db.listen(port); // listen for HTTP REST requests on a particular port
	
	

Note: The database keeps track of the last path you used to load using init(path). If you call init() a second (or third or fourth) time without a path, it will simply refresh from the same path as last time.

Administration

Clear

Clear all of the records in a single table asynchronously, then execute callback:

db.clearTable(table,callback)

Clear the entire database and then execute a callback

	db.clear(callback)

Direct API

The direct API provides access to the data from within the app that initialized multiwaydb. It loads the data file from the filesystem, and then handles all modification in memory, similar to sqlite.

db.set(table,key,value,callback); // set the "table" with key = value, and then execute "callback" asynchronously. 
db.update(table,key,value,callback); // alias for db.set()

db.patch(table,key,value,callback); // update the data "table" entry of value "key" with value by merging value and the data already in place, then execute "callback" asynchronously.
	db.create(table,value,callback); // create a new entry in "table" with value, then execute callback asynchronously. Callback will have single parameter, new entry id for success, or false for failure.

	db.get(table,key,callback); // get the value of key in "table", then execute callback asynchronously, passing the value as the argument to callback.
	db.get(table,callback); // get all of the records in "table, then execute callback asynchronously.

db.find(table,search,callback) // search table for records that match "search", and passe the results to callback as the argument. "search" should match the jsql syntax for searchjs package.

db.del(table,key,callback) // delete the record of key in table, and then execute callback.
db.destroy(table,key,callback) // alias for db.del()

For all API calls except create, an entry of "key" must already exist.

For create calls, you have 2 choices for creation of the key:

1. If value.id already exists, it will use it. In the case of a conflict, it will return an error "conflict" or a 409 for the REST API
2. If value.id does not exist, it will create one.

The algorithm for creating a new unique ID is as follows:

sha1.hash(new Date().toString().split("").sort(function(){return Math.round(Math.random())-0.5;}).join("")).substr(0,12)
	

Which essentially takes today's date as a full ISO string, randomly jumbles the characters, SHA1 hashes them, and then takes the first 12 characters. This is more than good enough for most non-production use. Actually, it is good enough for a ot of lightweight production use too.

For production use, you should use your own algorithms, or perhaps GUIDs. Either way, if you do not want to use this algorithm just override it by setting your own id property on the object.

Options for searching

The db.find() API to search for items has additional options beyond the usual searchjs options.

Field matches

The normal usage of search is to match field names and values, using standard searchjs

Thus, db.find('users',{age:35,gender:'male'}, callback) will find all records from the "users" table whose age field equals 35 and whose gender field equals "male".

You can use extended and complex searchjs searches; see the documentation there for complex matches.

Return options

In addition to the usual fields, any field in the search that begins with "$s." will be treated as a search option. It will not be passed to search js. Instead, it will be used to determine how to return results to you, and which ones. The following fields currently are supported. Examples follow.

• $s.sort: sort by a particular field, whether ascending or descending. Key is the term $s.sort, value is the name of the field. If it is given as is, sort ascending; if preceded by -, then descending.
• $s.count: return only a the first count number of records. Key is the term $s.count, value is an integer, how many records to return. It can be an actual number, or a string that can be converted to a number via parseInt(count,10)

Here are some examples.

• Get all of the users: db.find('users',{},callback)
• Get all of the users who are male: db.find('users',{gender:'male'},callback)
• Get the first 20 male users: db.find('users',{gender:'male',$s.count:20},callback) - note that these are the first 20 in the database, not necessarily sorted in any given order.
• Get all of the users sorted by ascending age: db.find('users',{'$s.sort':'age'},callback)
• Get all of the users sorted by descending age: db.find('users',{'$s.sort':'-age'},callback)
• Get the 20 youngest users: db.find('users',{'$s.sort':'age','$s.count':20},callback) - note that we sort ascending by age, so the first $s.count (i.e. 20 as given) users are the youngest
• Get the 10 oldest male users: db.find('users',{'gender':'male','$s.sort':'-age','$s.count':20},callback)

What is returned?

The callback always has the signature callback(err,res). If there are no errors, then err will be undefined or null.

The value of res depends on each case. In all cases, if there is an error, then res is the string value of the error.

• set/update/patch: no meaning.
• create: key of the newly created object.
• get: If a single item was requested as get("user","123") then a single JavaScript object as {id:"123",name:"john"}. If multiple items were requested as get("user",["123","456"]) then an array of such JavaScript objects as [{id:"123",name:"john"},{id:"456",name:"sally"}]
• find: Always an array of as many objects as were found, or null if none found.
• del/destroy: no meaning.

REST API

The REST API provides the same CRUD functionality as the direct API, but over HTTP.

GET

GET /table/:key

Get the record "key" from "table". Can have multiple keys, separated by commas

GET /table?search={a:1,b:2}

Search in table for records that match the value of "search" parameter. Parameter must be valid JSON that matches the parameters passed for search in db.find() in the direct API, and should be urlencoded. You can include the extended search options. See above at "Options for Searching".

PUT

PUT /table/:key
	

Replace the record "key" from "table" with the body of the http request. Body must be valid JSON.

PATCH

	PATCH /table/:key
	

Update the record "key" from "table" with the body of the http request. Body must be valid JSON.

POST

POST /table
	

Create a new record in "table" with the body of the http request. Body must be valid JSON.

DELETE

DELETE /table/:key
	

Delete record "key" from "table".

Remote API

The Remote API functions exactly like the Direct API, but accesses a remote multiwaydb over REST. You could just as easily use superagent or request to make REST API calls, but this is easier.

var db = require('multiwaydb').client(url); // You can have multiple of these, if you want

db.set(table,key,value,callback); // set the "table" with key = value, and then execute "callback" asynchronously. 
db.update(table,key,value,callback); // alias for db.set()

db.patch(table,key,value,callback); // update the data "table" entry of value "key" with value by merging value and the data already in place, then execute "callback" asynchronously.
db.create(table,value,callback); // create a new entry in "table" with value, then execute callback asynchronously. Callback will have single parameter, new entry id for success, or false for failure.

db.get(table,key,callback); // get the value of key in "table", then execute callback asynchronously, passing the value as the argument to callback.
db.get(table,callback); // get all of the records in "table, then execute callback asynchronously.

db.find(table,search,callback) // search table for records that match "search", and passe the results to callback as the argument. "search" should match the jsql syntax for searchjs package.

db.del(table,key,callback) // delete the record of key in table, and then execute callback.
db.destroy(table,key,callback) // alias for db.del()

Breaking Changes

As of v0.4.0, all Direct API and Remote API methods invoke the callback with the following signature:

callback(err,res);
	

This is consistent with most nodejs apps. Previously, some methods would simply invoke callback(res).

License

multiwaydb is released under the MIT License http://www.opensource.org/licenses/mit-license.php