How to do mongo db aggregation join operation in php? - mongodb

Question

I have three collections in mongodb like
employeeTitleTbl contains
{
"_id": ObjectId("5a7c2027d2ccda04d0006070"),
"EmployeeTitleName": "Librarian",
"EmployeeTitleCode": "ji8766",
..
}
DepartmentsTbl contains
{
"_id": ObjectId("5a817402d2ccda13240015a5"),
"DepartmentCode": "149",
"DepartmentName": "Biology",
..
}
EmployeesTbl contains
{
"_id": ObjectId("5a81957bd2ccda13240015a8"),
"EmployeeNumber": "25789998",
"JobTitle": ObjectId("5a7c2008d2ccda04d000606f"),
"Department": ObjectId("5a8173e6d2ccda13240015a4"),
...
}
I am very new to mongodb and also driver has also updated 3.6, so it is very difficult to find the latest method of aggregation in php. So I was tweaking the below code for adding department and employee title actual values like "EmployeeTitleName" and "DepartmentName" in EmployeesTbl.
public function fetchAll()
{
$pipeline = array(
array(
'$lookup' => array(
'from' => 'DepartmentsTbl',
'localField' => 'Department',
'foreignField' => '_id',
'as' => 'DepartmentDetails'
)
),
array(
'$lookup' => array(
'from' => 'employeeTitleTbl',
'localField' => 'JobTitle',
'foreignField' => '_id',
'as' => 'JobTitleDetails'
)
),
);
try
{
$cursor = $this->db->EmployeesTbl->aggregate($pipeline);
}
catch(Exception $e){
}
return $cursor->toArray();
}
Please help me in latest method!!!
The output is like
array(2) { [0]=> object(MongoDB\Model\BSONDocument)#29 (1) { ["storage":"ArrayObject":private]=> array(25) { ["_id"]=> object(MongoDB\BSON\ObjectId)#10 (1) { ["oid"]=> string(24) "5a8176c0d2ccda13240015a6" } ["EmployeeNumber"]=> string(8) "25799989"....
...........
["DepartmentDetails"]=> object(MongoDB\Model\BSONArray)#27 (1) { ["storage":"ArrayObject":private]=> array(0) { } } ["JobTitleDetails"]=> object(MongoDB\Model\BSONArray)#28 (1) { ["storage":"ArrayObject":private]=> array(0) { } } } } [1]=.........

Answer 1

You need to use $lookup to join 2 or more tables for example..
db.employeeTitle.aggregate([{
$lookup: {
from: 'employees',
localField: 'EmployeeTitleName',
foreignField: '_id',
as: 'employeeData'
}
},
{ $unwind: '$employeeData' },
{
$project: { profile: '$employeeData' }
}
])
It joins two tables employeeTitle and employees and give you full information about employees.