Mongoose find query - specific items or empty array

Question

I'm trying to build a filter where it should be possible to query all items selected in an array, but also to show documents where the property has not been set.

returning all specific from an array works fine with below

 searchCriteria.filter1 = {
          $in: array.category,
        };
 searchCriteria.filter2 = {
          $in: array.carbrand,
        };

//Then the data if fetched 
 const fetchedData = await Activity.find(searchCriteria)
      .sort({ date: -1 })
      .limit(limit)
      .skip(startIndex)
      .exec();

However, sometimes users have not added a category, and it's just a empty array. My goal is to get all of these empty arrays as well as the specific arrays.

so something like:

searchCriteria.filter2 = {
         $in: array.carbrand OR is []
       };

Any suggestions?

user20042973 · Accepted Answer · 2022-10-15 03:19:57Z

1

One way you could approach this is indeed to use the $or operator. But since $in is logically an OR for a single value, you should be able to just append [] to the list being used for comparison by the $in operator.

The approach is demonstrated in this playground example.

I believe you could adjust the code in a manner similar to this:

 searchCriteria.filter2 = {
          $in:  [...array.carbrand, []]
        };

answered Oct 15, 2022 at 3:19

user20042973

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2 Comments

Oscar Ekstrand Over a year ago

Thanks! This works great. I was stuck on the "OR" function - but this solution works great also when having multiple filters which all need this functionality, at the same time. :-)

user20042973 Over a year ago

Excellent! For general reference, the alternative syntax would be something like $or: [{filter2:{$in:array.carbrand}}, {filter2:[]}] }. But the documentation itself recommends $in over $or for situations like this anyway.

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