Find MongoDB records where array field is not empty

mongodb mongoose
skerit picture skerit · Feb 9, 2013 · Viewed 349.2k times · Source

All of my records have a field called "pictures". This field is an array of strings.

I now want the newest 10 records where this array IS NOT empty.

I've googled around, but strangely enough I haven't found much on this. I've read into the $where option, but I was wondering how slow that is to native functions, and if there is a better solution.

And even then, that does not work:

ME.find({$where: 'this.pictures.length > 0'}).sort('-created').limit(10).execFind()

Returns nothing. Leaving this.pictures without the length bit does work, but then it also returns empty records, of course.

Answer

Chris' picture Chris' · Aug 5, 2014

If you also have documents that don't have the key, you can use:

ME.find({ pictures: { $exists: true, $not: {$size: 0} } })

MongoDB don't use indexes if $size is involved, so here is a better solution:

ME.find({ pictures: { $exists: true, $ne: [] } })

Since MongoDB 2.6 release, you can compare with the operator $gt but could lead to unexpected results (you can find a detailled explanation in this answer):

ME.find({ pictures: { $gt: [] } })

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