> For the complete documentation index, see [llms.txt](https://docs.obto.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.obto.co/applications/data-aggregation.md).

# Data Aggregation

OBTO platform allows the execution of aggregation operations provided by MongoDB. *“Aggregation operations process data records and return computed results”*. To read more on the different types of available operations, please visit MongoDB’s website on [Aggregations](https://docs.mongodb.com/manual/aggregation/).

**Following examples illustrates how an aggregation structure will look like. You will first need to create a Data Source** under **Analytics** tab. It takes in the following parameters:

**Name:** unique name for this aggregation ( must be single word)

**Label:** Friendly label (spaces allowed)

**Collection:** collection name on which this aggregation is to run

**Script:** the aggregation code. It has the following object structure:

* **iproject**: contains all fields that are required for aggregation
* **match**: query to match records by.
* **group**: defines how to group records.
* **project**: defines what fields to project in the final result.
* **sort**: what field to sort final data on.

The script below is an example which fetches the attendance of all students in a class and groups them by the total counts for each student in class. Note: all operations used in the code below can be found on [MongoDB website](https://docs.mongodb.com/manual/reference/operator/aggregation/).

Code

```
{
  "iproject": {
    "present": {
      "$cond": {
        "if": {
          "$eq": ["$present", true]
        },
        "then": 1,
        "else": 0
      }
    },
    "domain": 1,
    "class_name": 1,
    "student_name": 1,
  },
  "match": {
    "class_name": "{{className}}"
  },
  "group": {
    "_id": {
      "name": "$student_name._id"
    },
    "present": {
      "$sum": "$present"
    },
    "total": {
      "$sum": 1
    }
  },
  "project": {
    "present": "$present",
    "total": "$total",
    "name": "$_id.name",
    "_id": 0
  },
  "sort": {
    "name": 1
  }
}
```