Introduction

MongoDB is a scalable, high-performance, open source, document-oriented database. The concepts used by MongoDB creators match very well Entity concepts. That's why a MongoDB driver is included within the standard Entity Library. Even if Entity is statically typed, defining a MongoDB document is as simple as it is with the mongo interactive shell.

Example

Here is an example of a Mongodb program written in Entity:

class Mongo_socket inherits Socket

	{
	public field waiting_requests: Integer_32: initial_value = 0 ;
	public constructor(self):

	{
	...() ;
	}

public method overloads incoming_data(self, buffer: object reference on Buffer):

	{
	waiting_requests -- ;
	error_stream.print("incoming_data size=%;\n", `[[` buffer->get_size() `]]`) ;
	var result = new Mongodb_reply ;
	result->use_buffer(buffer) ;
	var document = result->documents.first ;
	while (document != null) do

	{
	error_stream.print("%r;: %json;\n", `[[` document, document `]]`) ;
	document ++ ;
	}

if (result->cursor_id != 0)

	{
	waiting_requests ++ ;
	error_stream.print("send get_more\n") ;
	var get_more = new Mongodb_get_more(result->request_id, "mydb.foo", 10, result->cursor_id) ;
	get_more->send(&self) ;
	}

}

public method overloads disconnected(self):

	{
	error_stream.print("disconnected\n") ;
	}

}

class Mongodb_test

	{
	public field mongo: String: default_value = "127.0.0.1:27017" ;
	public method run(self) returns Integer_32:

	{
	var thread: Thread ;
	test_mongodb(&thread) ;
	return with 0 ;
	}

public method test_mongodb(self, thread: object reference on Thread):

	{
	var socket = new Mongo_socket ;
	thread->add_socket(socket) ;
	socket->connect("tcp://" + mongo) ;
	var query_1 = new Mongodb_query(22, "mydb.foo", 0, 0, 10, Mongodb_document { t: { `$exists` : true } }) ;
	socket->waiting_requests ++ ;
	query_1->send(socket) ;
	var update_1 = new Mongodb_update(23, "mydb.foo", 1, Mongodb_document { t: "xx" }, Mongodb_document { `$addToSet`: { x: { `$each`: "yellow" , "orange", "cyan" } }, xyz: true }) ;
	update_1->send(socket) ;
	var update_2 = new Mongodb_update(24, "mydb.foo", 1, Mongodb_document { t: "zz" }, Mongodb_document { t: "zz", a: 1, c: false }) ;
	update_2->send(socket) ;
	var update_3 = new Mongodb_update(25, "mydb.foo", 3, Mongodb_document { t: "xx" }, Mongodb_document { `$inc`: { a: 10.123498765 } }) ;
	update_3->send(socket) ;
	var insert_1 = new Mongodb_insert(26, "mydb.foo", 0) ;
	var a = 87654 ;
	insert_1->documents.insert(Mongodb_document { t: "aa", a: a }) ;
	insert_1->documents.insert(Mongodb_document { t: "ab", a: (a 2) }) ;
	insert_1->documents.insert(Mongodb_document { t: "ac", a: 100 }) ;
	insert_1->documents.insert(Mongodb_document { t: "ad", a: 100 }) ;
	insert_1->documents.insert(Mongodb_document { t: "ae", a: 100 }) ;
	insert_1->send(socket) ;
	var delete_1 = new Mongodb_delete(27, "mydb.foo", 0, Mongodb_document { t: "ac" }) ;
	delete_1->send(socket) ;
	var query_2 = new Mongodb_query(28, "mydb.foo", 0, 0, 10, Mongodb_document { t: { `$exists` : true } }) ;
	socket->waiting_requests ++ ;
	query_2->send(socket) ;
	error_stream.print("loop\n") ;
	while (socket->waiting_requests > 0) do

	{
	thread->wait() ;
	}

}

This a typical MongoDB program. We first do a query, then three updates and one insert and finally an other query.

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