Mongodb match on all but first array element

Question

I have a Mongodb document that contains an array of bookings like this:

{ id: myId,
  bookings: [
    {station: "Nurse"},
    {station: "Doctor"},
    {station: "Pharmacist"}
  ]
}

I have a view for each station where they see all records that are booked next. So for the Nurse, this would be: find({"bookings.0.station": "Nurse"}), returning every record where the nurse is the first element in the bookings array.

What I would like to add is a second view where all subsequent bookings can be seen, ie. records where the nurse is the nth booking for n > 0.

Is there a trivial way to do this? Or am I better off retrieving all documents first and then filtering on the actual document?

Neil Lunn · Accepted Answer · 2017-05-25 21:46:06Z

1

Just do both arguments. It's perfectly valid. So the query contains both the positive condition that looks at all elements and the $ne condition on only the first element:

db.bookings.find({ 
  "bookings.station": "Doctor", 
  "bookings.0.station": { "$ne": "Doctor" }
})

Returns, and:

db.bookings.find({
 "bookings.station": "Nurse", 
 "bookings.0.station": { "$ne": "Nurse" }
})

Does not. Which is the intent of course.

answered May 25, 2017 at 21:46

Neil Lunn

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1 Comment

Hans Over a year ago

So simple and elegant, how did I not figure that out myself. Thank you.

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