updating objects in double nested arrays in a collection - mongodb

Question

Having this schema:
Task = new SimpleSchema({
_id: {
type: String,
regEx: SimpleSchema.RegEx.Id,
autoValue: function(){ return Random.id(); }
},
title: {
type: String,
label: "Task title",
}
});
Card = new SimpleSchema({
_id: {
type: String,
regEx: SimpleSchema.RegEx.Id,
autoValue: function(){ return Random.id(); }
},
tasks: {
type: [Task],
label: "Card tasks",
optional: true
}
});
ProjectSchema = new SimpleSchema({
name: {
type: String,
label: "Project name"
},
cards: {
type: [Card],
label: "Project cards",
optional: true
}
});
I'm trying to update it with this function, passing the 3 ids and an object with the editted task:
editTask : function(projectId,cardId,taskId,oTask) {
if (! Meteor.userId()) {
throw new Meteor.Error("not-authorized");
}
check(projectId, String);
check(cardId, String);
check(taskId, String);
check(oTask, Object);
Projects.update({
_id: projectId,
cards: {
$elemMatch : {
_id: cardId,
tasks : {
_id : taskId
}
}
}
},
{
$set: {"tasks.$.Task": oTask}
});
}
Error says: when the modifier option is true, validation object must have at least one operator.
As far as I know that error means the $set: {"tasks.$.Task": oTask} it's not pointing correctly.
I've also tried: $set: {"cards.tasks.$.Task": oTask},$set: {"cards.$.tasks": oTask}