mongodb update field inside array
Consider the following document in the students collection whose grades element value is an array of embedded documents:
{
_id: 4,
grades: [
{ grade: 80, mean: 75, std: 8 },
{ grade: 85, mean: 90, std: 5 },
{ grade: 85, mean: 85, std: 8 }
]
}
Use the positional $ operator to update the std field of the first array element that matches the grade equal to 85 condition:
IMPORTANT
---------
You must include the array field as part of the query document.
db.students.updateOne(
{ _id: 4, "grades.grade": 85 },
{ $set: { "grades.$.std" : 6 } }
)
After the operation, the document has the following updated values:
{
"_id" : 4,
"grades" : [
{ "grade" : 80, "mean" : 75, "std" : 8 },
{ "grade" : 85, "mean" : 90, "std" : 6 },
{ "grade" : 85, "mean" : 85, "std" : 8 }
]
}