Delete empty array fields from MongoDB collection

Question

I have imported a csv file containing Programme data into a MongoDB collection. One of the fields, tags, is empty for some of the documents. Example:

"_id" : ObjectId("5906252136ac939ea93b4110"),
"pid" : "b00mtw7l",
"epoch_start" : ISODate("2009-02-05T08:16:00Z"),
"epoch_end" : ISODate("2009-02-12T08:16:00Z"),
"complete_title" : [
    "big and small",
    " series 1",
    " theres space for small"
],
"media_type" : "video",
"tags" : [""] //empty field, how to delete?

I want to delete the the empty tag fields entirely to reduce the redundancy of the data. How do I do this through the mongo shell rather than altering the csv file before importing it?

Thanks.

Do all of them have empty tags like this? Or some have actual tags? — Sergio Tulentsev
– Sergio Tulentsev, Commented May 11, 2017 at 18:44

gaganshera · Accepted Answer · 2017-05-11 18:49:42Z

3

Do it with

db.collection.update({tags: [""]},{$unset: {tags:1}},{multi: true});

{multi: true} will remove tags from multiple documents, wherever applicable.

edited May 11, 2017 at 18:49

answered May 11, 2017 at 18:29

gaganshera

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2 Comments

sums22 Over a year ago

Doesn't this remove the entire document? I want to just remove the tags field when it is empty.

gaganshera Over a year ago

@sums22 sorry didn't read the question properly. Updated my answer.

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