how can I modify a field name / key in a nested array of objects in mongodb? - mongodb

Question

I have a mongodb collection with a number of objects like this:
{
"_id" : "1234",
"type" : "automatic",
"subtypes" : [
{
"_id" : "dfgd",
"name" : "test subtype",
"subjetRequired" : true,
},
{
"_id" : "dfgd",
"name" : "test subtype2",
"subjetRequired" : false,
}
],
"anotherField" : "some value"
}
As you can see, one of the keys in the subtypes array is incorrectly spelled - "subjetRequired" instead of "subjectRequired".
I want to correct that key name. How can I do that.
I'll preface this by saying I've not worked with mongodb very much in the past.
After a lot of researching, the best I could come up with is the following (which doesn't work):
function remap(doc) {
subtypes = doc.subtypes;
var count = 0;
subtypes.forEach(function(subtype){
db.taskType.update({"_id": subtype._id}, {
$set: {"subtypes.subjectRequired" : subtype.subjetRequired},
$unset: {"subtypes.subjetRequired": 1}
});
}
)
}
db.taskType.find({"subtypes.subjetRequired":{$ne:null}}).forEach(remap);
This doesn't work.
I know the loop is correct, as if I replace the other logic with print statements I can access and print the fields who's names I want to modify.
What am I doing wrong here?

Answer 1

You can use this update and avoid using any code, it's also stable so you can execute it multiple times with no fear.
db.collection.updateMany({
"subtypes.subjetRequired": {
$exists: true
}
},
[
{
$set: {
subtypes: {
$map: {
input: "$subtypes",
in: {
$mergeObjects: [
"$$this",
{
subjectRequired: "$$this.subjetRequired",
}
]
}
}
}
}
},
{
$unset: "subtypes.subjetRequired"
}
])
Mongo Playground

Answer 2

I could modify your loop to override the whole array of subtypes:
function remap(doc) {
correctSubtypes = doc.subtypes.map(({ subjetRequired, ...rest }) => ({
...rest,
subjectRequired: subjetRequired,
}));
var count = 0;
db.taskType.findByIdAndUpdate(doc._id, {
$set: {
subtypes: correctSubtypes,
},
});
}