`.avg()`

Get the aggregate mean of the specified attribute across all matching records.

usage

var average = await Something.avg(numericAttrName, criteria);

Usage

	Argument	Type	Details
1	numericAttrName	((string))	The name of the numeric attribute whose mean will be calculated.
2	criteria	((dictionary?))	The Waterline criteria to use for matching records in the database. If no criteria is specified, the average will be computed across all of this model's records. `avg` queries do not support pagination using `skip` and `limit` or projections using `select`.

Result

Type	Description
((number))	The aggregate mean of the specified attribute across all matching records.

Errors

Name	Type	When?
UsageError	((Error))	Thrown if something invalid was passed in.
AdapterError	((Error))	Thrown if something went wrong in the database adapter.
Error	((Error))	Thrown if anything else unexpected happens.

See Concepts > Models and ORM > Errors for examples of negotiating errors in Sails and Waterline.

Example

Get the average balance of bank accounts owned by people between the ages of 35 and 45.

javascript

var averageBalance = await BankAccount.avg('balance')
.where({
  ownerAge: { '>=': 35, '<=': 45 }
});

Notes

This method can be used with await, promise chaining, or traditional Node callbacks.

Some databases like MySQL may return null for this kind of query, however it's best practice for Sails/Waterline adapter authors to return 0 for consistency and type safety in app-level code.