Ignoring NULL values within an aggregate operation in MongoDB

Question

I have the following MongoDB aggregate operation which is working fine but it also seems to be returning NULL values.

How can I ignore NULL values against projectIP field?

db.inventory.aggregate(
    [
     { $match:   {projectIP: { $exists:true }}},
     { $project: {projectIP: "$projectIP",_id : 0}},
     { $group:   {_id: "$projectIP"}},
     { $sort:    {projectIP: 1}}
    ];
)

@Anthony Winzlet unfortunately didn't seem to work. Added this after the $sort{} — tonyf
– tonyf, Commented May 14, 2019 at 13:39
Not after the $sort. This should be the top of the pipeline above $project — Ashh
– Ashh, Commented May 14, 2019 at 13:40
@Anthony Winzlet Added to the top as shown in updated question and sorry, still showing my NULL value in my select drop-down list. — tonyf
– tonyf, Commented May 14, 2019 at 13:43
Seems some of the keys contain null values. Add this as well { $match: { projectIP: { $exists:true, $ne: null }}} by replacing the first stage in your query — Ashh
– Ashh, Commented May 14, 2019 at 16:12

Ashh · Accepted Answer · 2019-05-15 03:09:46Z

1

Seems some of the keys contain null values. Add this as well

{ $match: { projectIP: { $exists:true, $ne: null }}}

by replacing the first stage in your query

answered May 15, 2019 at 3:09

Ashh

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Yusuf Arapoglu · Accepted Answer · 2019-05-14 13:30:54Z

1

You can assign a value (0 or anything) to them instead of a null value.

Here how you do it

projectIP: { $ifNull: [ "$projectIP", 0.0 ] }

answered May 14, 2019 at 13:30

Yusuf Arapoglu

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3 Comments

tonyf Over a year ago

Will this actually ignore the NULL value as I am displaying the values in a select drop-down list where I don't want to show any NULLs.

Yusuf Arapoglu Over a year ago

It will not ignore null values but will assign null fields a value. Useful if your code throws an exception with null values.

tonyf Over a year ago

Thanks for the info but in this scenario, I need the null values ignored altogether.

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