I have this schema:{ key: [] }. I want to convert it to { key: { foo: number } }.
This is the query I came up with:
db.collection.update({}, [
{
"$set": {
key: { foo: 43 }
}
}
], { multi: true })
However, it updates the individual array item instead of the array as a whole. I.e. the document:
{ key: [1, 2] }
becomes :
{ key: [ { foo: 43 }, { foo: 43 } ] }
instead of:
{ key: { foo: 43 } }.
I just want to get rid of the original array completely. I can just remove the field, then write the update. But is there a way to do it in one fell swoop?
Update: I have to use the pipeline, there’re other stuff going on.
5
As per this comment:
I just want to get rid of the original array completely. I don’t use the original value.
In that case, don’t use the pipeline syntax for update. So you only need to remove the [...] surrounding $set:
db.collection.update({},
{
"$set": {
key: { foo: 43 }
}
},
{ multi: true })
And if you do need an update pipeline for some other steps, then unset key before setting a new value:
db.collection.update({},
[
{ $unset: "key" },
{
$set: {
key: { foo: 43 }
}
}
],
{ multi: true }
)
Mongo Playground
Use $literal
db.collection.update({},
[
{
"$set": {
"key": {
"$literal": {
"foo": 43
}
}
}
}
])
Mongo Playground
1