Retrieve fields of Mongo collection in PHP - php

Question

I tried using the fields() method on the cursor:
<?php
$mongo = new Mongo("mongodb://localhost");
print_r($mongo);
$db = $mongo->test;
// access collection
$collection = $db->test;
// execute query
// retrieve all documents
print_r($test);
$cursor = $collection->find();
print_r($cursor);
$fields = $cursor->fields(array("summary" => true));
print_r($fields);
The output is:
Mongo Object ( [connected] => 1 [status] => [server:protected] => [persistent:protected] => )
MongoCursor Object ( )
MongoCursor Object ( )
Looks like the driver and the connection work but I can't retrieve the distinct summarization of the fields.

Answer 1

Assume that we have access to mongodb database with the name db, are going to retrieve data from MyCollection and use MongoDB\Driver\Manager:
$manager = new MongoDB\Driver\Manager( $DB_CONNECTION_STRING );
Then we retrieve data in this case by name with a limit 2 documents and want to get only fields name, age and address among many others. Projection option can be used to specify which fields should be returned using 0 to exclude and 1 to include:
$filter = ['name' => 'John'];
$options = [ 'projection' => ['_id' => 0, 'name' => 1, 'age' => 1, 'address' => 1], 'limit' => 2 ];
$query = new MongoDB\Driver\Query($filter, $options);
$manager->executeQuery('db.MyCollection', $query);
If we need to get all columns, then we simply omit projection option at all as the following:
$filter = ['name' => 'daniel'];
$options = [];
$query = new MongoDB\Driver\Query($filter, $options);
$manager->executeQuery('db.MyCollection', $query);

Answer 2

const HOST = 'localhost';
const PORT = 27017;
const DBNAME = 'test';
const COLLECTION = 'test';
$connectionString = sprintf('mongodb://%s:%d', HOST, PORT);
try {
$connection = new Mongo($connectionString);
$database = $connection->selectDB(DBNAME);
} catch (MongoConnectionException $e) {
throw $e;
}
$collection = $database->selectCollection(COLLECTION);
try{
$query = array();
$specifyKey = array("summary" => true);
$cursor = $collection->find($query , $specifyKey);
}catch(MongoException $e) {
die('Failed to find One data '.$e->getMessage());
}catch (MongoCursorException $e) {
echo "error message: ".$e->getMessage()."\n";
echo "error code: ".$e->getCode()."\n";
}
while ($cursor->hasNext()){
$nextCursor = $cursor->getNext();
//process next cursor
}

Answer 3

After the $cursor variable try an foreach instead. It goes through the cursor results.
foreach($cursor as $document) {
var_dump($document);
}