---
title: "system.mongodb.aggregate"
description: "Returns a list of aggregate results."
---

# system.mongodb.aggregate

> Returns a list of aggregate results.

This function is used in **Python Scripting**.

:::note
Project Library scripts will not provide hints for MongoDB system functions unless the Script Hint Scope is set to **Gateway**. See the [Scripting in Ignition](platform\scripting\scripting-in-ignition\scripting-in-ignition.md#system-functions-hints-and-autocomplete) page for more details on scripting hints.
:::

## Description
## Client Permission Restrictions
This scripting function has no [Client Permission](../../../ignition-modules/vision/vision-project-properties/vision-project-properties.md#vision-permissions-properties) restrictions.

## Syntax
`system.mongodb.aggregate(connector, collection, aggregate, [collation])`

### Parameters
Type | Parameter | Description 
------- | ------- | ------
String| `connector` | The name of connector (case-insensitive).
String| `collection` | The name of collection (case-sensitive).
List[PyDictionary]| `aggregate` | A list of PyDictionaries to specify an aggregate pipeline. [See MongoDB documentation](https://www.mongodb.com/docs/manual/aggregation/) for all valid aggregate options.
PyDictionary| `collation` | A PyDictionary of items to specify language-specific rules. [See MongoDB documentation](https://www.mongodb.com/docs/manual/reference/collation/) for all valid collation values. [optional]

### Returns
**List[PyDictionary]** result - A list of PyDictionary results containing aggregation results.

### Scope
Gateway, Perspective Session

## Importing Classes
You can import classes from system.mongodb.types like you would other Python classes:

#### Example
```
from system.mongodb.types import ObjectId
 
newObjectId = ObjectId.get()
```

You can also iterate those system.mongodb.types packages to see all available classes:

#### Example
```
for d in dir(system.mongodb.types):
    print d
```

### API Docs
MongoDB-specific data types come from the org.bson.types package of the Mongo Java Driver API. The library of classes available for import can be accessed at this link: [Mongo Java Driver 3.6.0 API Docs for Package org.bson.types](https://mongodb.github.io/mongo-java-driver/3.6/javadoc/org/bson/types/package-summary.html).

## Types References
The following values can be referenced for the types parameter at system.mongodb.types:
```
Binary
Code
CodeWScope
CodeWithScope
Decimal128
INSTANCE
MaxKey
MinKey
ObjectId
Symbol
Timestamp
```

## Code Examples
```python title="Example #1"
# Retrieve a both a connector name to query from.
connector = system.mongodb.listConnectorInfo()[0]['name']
  
# Specify aggregate that will find the sum of all key value pairs named transaction_count.
aggregate = [
                {"$group":
                    { "_id": '',
                    "OverallTransactionTotal":{"$sum": "$transaction_count"}
                    }
                }
            ]
              
# Apply all parameters for our function call.
result = system.mongodb.aggregate(connector, "transactions", aggregate)
   
# Print the result. Here it is expected that the aggregate parameter's key OverallTransactionTotal can be extracted.
print "Overall Transaction Total: " + str(result[0]["OverallTransactionTotal"])
```