MongoDB Aggregation $addFields
Aggregation $addFields
This aggregation stage adds new fields to documents.
Example
In this example, we are using the "sample_restaurants" database loaded from our sample data in the Intro to Aggregations section.
db.restaurants.aggregate([
{
$addFields: {
avgGrade: { $avg: "$grades.score" }
}
},
{
$project: {
"name": 1,
"avgGrade": 1
}
},
{
$limit: 5
}
])
This will return the documents along with a new field,
avgGrade,
which will contain the average of each restaurants grades.score.
