localStorageDB 2.3.1

localStorageDB is a simple layer over localStorage (and sessionStorage) that provides a set of functions to store structured data like databases and tables. It provides basic insert/update/delete/query capabilities. localStorageDB has no dependencies, and is not based on WebSQL. Underneath it all, the structured data is stored as serialized JSON in localStorage or sessionStorage.

Kailash Nadh
v 2.3.1 Mar 2015
v 2.3.0 Feb 2014 Contribution: Christian Kellner (http://orange-coding.net)
v 2.2 Jan 2014 Contribution: Andy Hawkins (http://a904guy.com)
v 2.1 Nov 2013
v 2.0 Jun 2013
v 1.9 Nov 2012
Documentation: http://nadh.in/code/localstoragedb
Licensed: MIT license

Installation

bower install localstoragedb

Run Test Cases

bower install # install mocha and chai for running test cases

open test/local_storage_db_test.html in Browser to check the result

Supported Browsers

Browsers need to support "Local Storage" in order to make localeStorageDB working.

IE 8<
Firefox 31<
Chrome 31<
Safari 7<
iOS Safari 7.1<
Android Browser 4.1<
Chrome for Android 42<

Usage / Examples

Creating a database, table, and populating the table

// Initialise. If the database doesn't exist, it is created
var lib = new localStorageDB("library", localStorage);

// Check if the database was just created. Useful for initial database setup
if( lib.isNew() ) {

    // create the "books" table
	lib.createTable("books", ["code", "title", "author", "year", "copies"]);
	
	// insert some data
	lib.insert("books", {code: "B001", title: "Phantoms in the brain", author: "Ramachandran", year: 1999, copies: 10});
	lib.insert("books", {code: "B002", title: "The tell-tale brain", author: "Ramachandran", year: 2011, copies: 10});
	lib.insert("books", {code: "B003", title: "Freakonomics", author: "Levitt and Dubner", year: 2005, copies: 10});
	lib.insert("books", {code: "B004", title: "Predictably irrational", author: "Ariely", year: 2008, copies: 10});
	lib.insert("books", {code: "B005", title: "Tesla: Man out of time", author: "Cheney", year: 2001, copies: 10});
	lib.insert("books", {code: "B006", title: "Salmon fishing in the Yemen", author: "Torday", year: 2007, copies: 10});
	lib.insert("books", {code: "B007", title: "The user illusion", author: "Norretranders", year: 1999, copies: 10});
	lib.insert("books", {code: "B008", title: "Hubble: Window of the universe", author: "Sparrow", year: 2010, copies: 10});
	
	// commit the database to localStorage
	// all create/drop/insert/update/delete operations should be committed
	lib.commit();
}

Creating and populating a table in one go

	// rows for pre-population
	var rows = [
		{code: "B001", title: "Phantoms in the brain", author: "Ramachandran", year: 1999, copies: 10},
		{code: "B002", title: "The tell-tale brain", author: "Ramachandran", year: 2011, copies: 10},
		{code: "B003", title: "Freakonomics", author: "Levitt and Dubner", year: 2005, copies: 10},
		{code: "B004", title: "Predictably irrational", author: "Ariely", year: 2008, copies: 10},
		{code: "B005", title: "Tesla: Man out of time", author: "Cheney", year: 2001, copies: 10},
		{code: "B006", title: "Salmon fishing in the Yemen", author: "Torday", year: 2007, copies: 10},
		{code: "B007", title: "The user illusion", author: "Norretranders", year: 1999, copies: 10},
		{code: "B008", title: "Hubble: Window of the universe", author: "Sparrow", year: 2010, copies: 10}
	];

	// create the table and insert records in one go
	lib.createTableWithData("books", rows);

	lib.commit();

Altering

// If database already exists, and want to alter existing tables
if(! (lib.columnExists("books", "publication")) ) {
	lib.alterTable("books", "publication", "McGraw-Hill Education");
	lib.commit(); // commit the deletions to localStorage
}

// Multiple columns can also added at once
if(! (lib.columnExists("books", "publication") && lib.columnExists("books", "ISBN")) ) {
	lib.alterTable("books", ["publication", "ISBN"], {publication: "McGraw-Hill Education", ISBN: "85-359-0277-5"});
	lib.commit(); // commit the deletions to localStorage
}

Querying

query() is deprecated. Use queryAll() instead.

// simple select queries
lib.queryAll("books", {
	query: {year: 2011}
});
lib.queryAll("books", {
	query: {year: 1999, author: "Norretranders"}
});

// select all books
lib.queryAll("books");

// select all books published after 2003
lib.queryAll("books", {
	query: function(row) {    // the callback function is applied to every row in the table
		if(row.year > 2003) {		// if it returns true, the row is selected
			return true;
		} else {
			return false;
		}
	}
});

// select all books by Torday and Sparrow
lib.queryAll("books", {
    query: function(row) {
            if(row.author == "Torday" || row.author == "Sparrow") {
		        return true;
	        } else {
		        return false;
	    }
    },
    limit: 5
});

Sorting

// select 5 rows sorted in ascending order by author
lib.queryAll("books", { limit: 5,
                        sort: [["author", "ASC"]]
                      });

// select all rows first sorted in ascending order by author, and then, in descending, by year
lib.queryAll("books", { sort: [["author", "ASC"], ["year", "DESC"]] });

lib.queryAll("books", { query: {"year": 2011},
                        limit: 5,
                        sort: [["author", "ASC"]]
                      });

// or using query()'s positional arguments, which is a little messy (DEPRECATED)
lib.query("books", null, null, null, [["author", "ASC"]]);

Distinct records

lib.queryAll("books", { distinct: ["year", "author"]
                      });

Example results from a query

// query results are returned as arrays of object literals
// an ID field with the internal auto-incremented id of the row is also included
// thus, ID is a reserved field name

lib.queryAll("books", {query: {author: "ramachandran"}});

/* results
[
 {
   ID: 1,
   code: "B001",
   title: "Phantoms in the brain",
   author: "Ramachandran",
   year: 1999,
   copies: 10
 },
 {
   ID: 2,
   code: "B002",
   title: "The tell-tale brain",
   author: "Ramachandran",
   year: 2011,
   copies: 10
 }
]
*/

Updating

// change the title of books published in 1999 to "Unknown"
lib.update("books", {year: 1999}, function(row) {
	row.title = "Unknown";
	
	// the update callback function returns to the modified record
	return row;
});

// add +5 copies to all books published after 2003
lib.update("books",
	function(row) {	// select condition callback
		if(row.year > 2003) {
			return true;
		} else {
			return false;
		}
	},
	function(row) { // update function
		row.copies+=5;
		return row;
	}
);

Insert or Update conditionally

// if there's a book with code B003, update it, or insert it as a new row
lib.insertOrUpdate("books", {code: 'B003'}, {	code: "B003",
						title: "Freakonomics",
						author: "Levitt and Dubner",
						year: 2005,
						copies: 15});

Deleting

// delete all books published in 1999
lib.deleteRows("books", {year: 1999});

// delete all books published before 2005
lib.deleteRows("books", function(row) {
	if(row.year < 2005) {
		return true;
	} else {
		return false;
	}
});

lib.commit(); // commit the deletions to localStorage

Methods

	<tr>
		<td>tableExists()</td>
		<td>table_name</td>
		<td>Checks whether a table exists in the database</td>
	</tr>
	<tr>
		<td>tableFields()</td>
		<td>table_name</td>
		<td>Returns the list of fields of a table</td>
	</tr>
	<tr>
		<td>createTable()</td>
		<td>table_name, fields</td>
		<td>Creates a table<br />
			- fields is an array of string fieldnames. 'ID' is a reserved fieldname.
		</td>
	</tr>
	<tr>
		<td>createTableWithData()</td>
		<td>table_name, rows</td>
		<td>Creates a table and populates it<br />
			- rows is an array of object literals where each object represents a record<br />
			[{field1: val, field2: val}, {field1: val, field2: val}]
		</td>
	</tr>
	<tr>
		<td>alterTable()</td>
		<td>table_name, new_fields, default_values</td>
		<td>Alter a table<br />
			- new_fields can be a array of columns OR a string of single column.<br />
			- default_values (optional) can be a object of column's default values OR a default value string for single column for existing rows.
		</td>
	</tr>
	<tr>
		<td>dropTable()</td>
		<td>table_name</td>
		<td>Deletes a table from the database</td>
	</tr>
	<tr>
		<td>truncate()</td>
		<td>table_name</td>
		<td>Empties all records in a table and resets the internal auto increment ID to 0</td>
	</tr>
	<tr>
		<td>columnExists()</td>
		<td>table_name, field_name</td>
		<td>Checks whether a column exists in database table.</td>
	</tr>
	<tr>
		<td>rowCount()</td>
		<td>table_name</td>
		<td>Returns the number of rows in a table</td>
	</tr>

	
	<tr>
		<td>insert()</td>
		<td>table_name, data</td>
		<td>Inserts a row into a table and returns its numerical ID<br />
			- data is an object literal with field-values<br />
			Every row is assigned an auto-incremented numerical ID automatically
		</td>
	</tr>
	<tr>
		<td>query() DEPRECATED</td>
		<td>table_name, query, limit, start, sort</td>
		<td></td>
	</tr>
    <tr>
		<td>queryAll()</td>
		<td>table_name, params{}</td>
		<td>
			Returns an array of rows (object literals) from a table matching the query.<br />
			- query is either an object literal or null. If query is not supplied, all rows are returned<br />
			- limit is the maximum number of rows to be returned<br />
			- start is the  number of rows to be skipped from the beginning (offset)<br />
			- sort is an array of sort conditions, each one of which is an array in itself with two values<br />
			- distinct is an array of fields whose values have to be unique in the returned rows<br />
			Every returned row will have it's internal auto-incremented id assigned to the variable ID</td>
	</tr>
	<tr>
		<td>update()</td>
		<td>table_name, query, update_function</td>
		<td>Updates existing records in a table matching query, and returns the number of rows affected<br />
			- query is an object literal or a function. If query is not supplied, all rows are updated<br />
			- update_function is a function that returns an object literal with the updated values
		</td>
	</tr>
		<tr>
			<td>insertOrUpdate()</td>
			<td>table_name, query, data</td>
			<td>Inserts a row into a table if the given query matches no results, or updates the rows matching the query.<br />
				- query is either an object literal, function, or null.<br />
				- data is an object literal with field-values
				<br /><br />
				Returns the numerical ID if a new row was inserted, or an array of IDs if rows were updated
			</td>
		</tr>
	<tr>
		<td>deleteRows()</td>
		<td>table_name, query</td>
		<td>Deletes rows from a table matching query, and returns the number of rows deleted<br />
			- query is either an object literal or a function. If query is not supplied, all rows are deleted
		</td>
	</tr>
</tbody>

Method	Arguments	Description
localStorageDB()	database_name, storage_engine	Constructor - storage_engine can either be localStorage (default) or sessionStorage
isNew()		Returns true if a database was created at the time of initialisation with the constructor
drop()		Deletes a database, and purges it from localStorage
tableCount()		Returns the number of tables in a database
commit()		Commits the database to localStorage. Returns true if successful, and false otherwise (highly unlikely)
serialize()		Returns the entire database as serialized JSON

flyking/localStorageDB