Mongoose: updating a single sub-document issues - node.js

Question

Schema:
var educationSchema = new Schema({
schoolName: String,
startDate: Number,
endDate: Number,
degree: String,
major: String,
grade: String
});
var UserSchema = new Schema({
firstName: String,
lastName: String,
education: [educationSchema]
});
Update code:
User.findOneAndUpdate(
{"_id": req.user.id, "education._id": req.body.id},
{
"$set": {
"education.$": req.body
}
},
function(err, edu) {
}
);
Now, if the user only edits the schoolName on the UI the following happens:
Pre-save State:
{
"_id" : ObjectId("5878fb4f51ec530358fea907"),
"firstName" : "John",
"lastName" : "Doe",
"education" : [
{
"schoolName" : "ABC",
"startDate" : 1998,
"endDate" : 2005,
"degree" : "Bachelor’s Degree",
"major" : "CS",
"grade" : "3.5",
"_id" : ObjectId("5878fbb951ec530358fea909")
}
]
}
Post-save State:
"education" : [
{
"schoolName" : "XYZ"
}
]
Is $set not the right operator to use?

Answer 1

Updating education.$ updates the sub-document. If you want to update only the schoolName you must use education.$.schoolName.
Change your update code to:
User.findOneAndUpdate(
{"_id": req.user.id, "education._id": req.body.id},
{
"$set": {
"education.$.schoolName": req.body
}
},
function(err, edu) {
}
);
EDIT: (update any field sent through req.body)
const update = {};
Object.getOwnPropertyNames(req.body).forEach(key => {
update['education.$.' + key] = req.body[key];
});
User.findOneAndUpdate(
{"_id": req.user.id, "education._id": req.body.id},
{
"$set": update
},
function(err, edu) {
}
);