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.avg()

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

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

Usage

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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.

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

Notes

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  • 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.

Is something missing?

If you notice something we've missed or could be improved on, please follow this link and submit a pull request to the sails repo. Once we merge it, the changes will be reflected on the website the next time it is deployed.

Reference

Reference