How to remove elements with missing field in a MongoDB array?

Question

Recently I'm learning MongoDB and Python by myself and I encounter this problem.

https://i.sstatic.net/acQxl.png

For object 1-3 there is date information in it but some object does not contain date on it. How can I remove the object that doesn't contain date in it by using MongoDB and Python script?Thanks in advance.

"Remove missing data" is contradictory. Either you have data which you like to remove or the data is missing. Please don't paste images, provide documents as formatted text, see meta.stackoverflow.com/a/285557/3027266 — Wernfried Domscheit
– Wernfried Domscheit, Commented Jan 31, 2021 at 12:56

Mohammad Yaser Ahmadi · Accepted Answer · 2021-02-01 06:04:14Z

1

just try

update(
{} ,
{ "$pull": { data :{ date: { "$exists":  false } }} },
false,true)

edited Feb 1, 2021 at 6:04

answered Jan 31, 2021 at 11:43

Mohammad Yaser Ahmadi

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3 Comments

evasim Over a year ago

This command is not working in my MongoDB..it popout unknown expression $exists

Mohammad Yaser Ahmadi Over a year ago

If you use with double cotatiob or without $ whats happend?

evasim Over a year ago

I manage to get it run on my MongoDB.thanks.Is this the same way to do in Python 3?

Gibbs · Accepted Answer · 2021-01-31 11:24:25Z

0

Use $pull to remove items from the array.

$pull

Find part of update: Use $exists on date field to check the existence.

db.coll.update({},
{
  "$pull": {
    "arr": {
      "a": {
        exists: false
      }
    }
  }
})

edited Jan 31, 2021 at 11:24

answered Jan 31, 2021 at 11:11

Gibbs

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2 Comments

evasim Over a year ago

I thought of using $pull but I thought pull is for existing data.Can you show me the command for my question above?Thanks

Gibbs Over a year ago

db.coll.update({}, { "$pull": { "arr": { "a": { exists: false } } } }) Please try this

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