How to get elements from an array from a index to the end

Question

Sample Mongo Document

chat = { _id: someid, messages: [{text: 'aaa'}, {text: 'bbb'}, {text: 'ccc'}, {text: 'ddd'}] }

I need to extract messages starting from index 1 till the end of the array. Thanks.

Codes tried so far:

let theIndex = 1;
Model.aggregate(
  { $match: condition },
  { $project: { 'chat': { $slice: ['$chat.messages', theIndex, 25]  } } }
)

This will give me 25 messages, but i need it to be till the end of the array.

Hope the question is clear.

Still need clarification on what you want. Also post the code what you have tried so far — Subburaj
– Subburaj, Commented Jan 3, 2020 at 9:26

mickl · Accepted Answer · 2020-01-03 09:34:14Z

1

You can just use $size as a last $slice parameter:

let theIndex = 1;
Model.aggregate(
   { $match: condition },
   { $project: { 'chat': { $slice: ['$chat.messages', theIndex, { $size: '$messages' }]  } } }
)

answered Jan 3, 2020 at 9:34

mickl

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