ZCCADCDEDB567ABAE643E15DCF0974E503Z 按 ObjectID 从嵌套数组中拉出一个元素

Question

I have a Schedule Schema and I'm trying to an element from a nested slotsPerDay array.

const scheduleSchema =  mongoose.Schema({
    course_id: {{type: mongoose.Schema.Types.ObjectId, ref: 'course' }}, 
    week_schedule: [{
        day: {type: String, required: true },
        slotsPerDay: [{type: mongoose.Schema.Types.ObjectId, ref: 'slots' }],
    }]
});

I'm trying to delete a certain slot ObjectID from the slotsPerDay array that's encapsulated inside the week_schedule array as follows.

 SchemaModel.findOneAndUpdate(
         {course_id: req.body.course_id},
         { "$pull": { "week_schedule": { "slotsPerDay": {"_id": req.body.slotID }}}}
 ,{new:true})

However, this query deletes the whole week_schedule array with all it's slots, not just the one mapping to the slotID given in query. Any help fixing that?

I tried { "$pull": { "week_schedule.slotsPerDay": {"_id": req.body.slotID }}} but I get the error

Cannot use the part (slotsPerDay) of (week_schedule.slotsPerDay) to traverse the element ({week_schedule: [ { slotsPerDay: [ ObjectId('5fe0263872f7b53aac93334a'), ObjectId('5fe0263872f7b53aac933349'), ObjectId('5fe0263872f7b53aac93334b'), ObjectId('5fe0263872f7b53aac93334c'), ObjectId('5fe0263872f7b53aac93334d'), ObjectId('5fe0263872f7b53aac93334e'), ObjectId('5fe0263872f7b53aac93334f'), ObjectId('5fe0263872f7b53aac933350') ], _id: ObjectId('5fe0266a72f7b53aac933364'), day: "Saturday" }, { slotsPerDay: [], _id: ObjectId('5fe0266a72f7b53aac933365'), day: "Sunday" }, { slotsPerDay: [], _id: ObjectId('5fe0266a72f7b53aac933366'), day: "Monday" }, { slotsPerDay: [ ObjectId('5fe0263872f7b53aac933356'), ObjectId('5fe0263872f7b53aac933357'), ObjectId('5fe0263872f7b53aac933359'), ObjectId('5fe0263872f7b53aac93335a') ], _id: ObjectId('5fe0266a72f7b53aac933368'), day: "Wednesday" }, { slotsPerDay: [ ObjectId('5fe0263872f7b53aac93335b'), ObjectId('5fe0263872f7b53aac93335c'), ObjectId('5fe0263872f7 b53aac93335d'), ObjectId('5fe0263872f7b53aac93335e'), ObjectId('5fe0263872f7b53aac93335f'), ObjectId('5fe0263872f7b53aac933360'), ObjectId('5fe0263872f7b53aac933361'), ObjectId('5fe0263872f7b53aac933362') ], _id: ObjectId('5fe0266a72f7b53aac933369'), day: "Thursday" } ]})

Answer 1

Try this:

SchemaModel.findOneAndUpdate(
     { course_id: req.body.course_id },
     { $pull: { "week_schedule.$[].slotsPerDay": req.body.slotID }},
     { new: true })

It uses the all positional operator , $[] . For all elements in the week_schedule array, it pulls elements from the nested slotsPerDay array with a value equal to req.body.slotID .