I'm using MongoChef to construct an aggregation pipeline command that performs a $match, then a $group then a $project.
The following code produces the correct output and is confirmed working in MongoDB itself:
db.collection_name.aggregate(
[
{
$match: {
":energy_mon_id" : 9
}
},
{
$group: {
"_id" : {
"Date" : "$:date"
},
"avg_voltage_a" : {
"$avg" : "$:voltage_a"
},
"avg_voltage_b" : {
"$avg" : "$:voltage_b"
},
"avg_voltage_c" : {
"$avg" : "$:voltage_c"
}
}
},
{
$project: {
"avg_volt" : {
"$add" : [
"$avg_voltage_a",
"$avg_voltage_b"
]
}
}
},
{
$match: {
}
}
]
);
The output that is produced is this (note that the avg_volt values are integers):
{ "_id" : { "Date" : "2016-06-06" }, "avg_volt" : 779 }
{ "_id" : { "Date" : "2016-06-08" }, "avg_volt" : 779 }
Now the issue I'm faced with is getting this to run correctly in PHP.
My code in PHP is below:
$collection = $this->db->testdb->collection_name;
$aggrCommand = array(
array(
'$match' => array( ":energy_mon_id" => 9)
),
array(
'$group' => array(
"_id" => array(
"Date" => "$:date"
),
"avg_voltage_a" => array(
'$avg' => "$:voltage_a"
),
"avg_voltage_b" => array(
'$avg' => "$:voltage_b"
),
"avg_voltage_c" => array(
'$avg' => "$:voltage_c"
),
)
),
array(
'$project' => array(
"avg_volt" => array(
'$add' => ["$avg_voltage_a","$avg_voltage_b" ]
)
)
)
);
$list = $collection->aggregate( $aggrCommand);
The error I get is for this very last line when I try to submit a GET request via postman:
Slim Application Error
The application could not run because of the following error:
Details
Type: MongoDB\Driver\Exception\RuntimeException
Code: 16554
Message: $add only supports numeric or date types, not String
File: C:\wamp\www\DRM\vendor\mongodb\mongodb\src\Operation\Aggregate.php
Line: 168
This makes no sense at all since the output in MongoDB is an integer value, and I can't spot any errors in my conversion to PHP.
One thing to note is that my field names do actually contain a colon at the front (its not a mistake), but I don't think that is the issue here.
I'm really stumped with this, can someone provide any advice on how to figure this issue out? The output from my MongoDB command is clearly not a string, yet in PHP it says the values of avg_voltage_a and avg_voltage_b are strings. This makes no sense at all.
