Web7 sep. 2014 · The $exists operator is a "query" operator, so it is used basically to "filter" results rather than identify a logical condition. As a "logical" operator the aggregation … Web30 jul. 2024 · How to apply a condition only if field exists in MongoDB - You can use $or operator for this. Let us first create a collection with documents −> …
$ifNull (aggregation) — MongoDB Manual
WebIf you value query performance never use $exists (or use it only when you have a sparse index over the field that is queried. the sparse index should match the criteria of the … Web22 nov. 2024 · In MongoDB, we can check the existence of the field in the specified collection using the $exists operator. When the value of $exists operator is set to true, … state home insurance
MongoDB select optional fields or defaults if exist
Web6 uur geleden · The main problem is that I only want to select a few root fields and the "de" fields. If "de" is not available, "en" should be selected and returned. And should it be possible, if both cases are not present, that the first best one is returned, then it would be unbelievable. At the end i transform the document into a flattet new one. At the end WebCurrently the $exists operator is not available in the aggregation pipeline. edit: Writing up a better answer: You could check if any user has commented, by: using $setIntersection … Web24 nov. 2024 · In MongoDB, we use the find () method to retrieve data. However, find () retrieves all the fields in a document without any filtering. MongoDB projection solves this problem by enabling the find () function to be used with data filtering arguments, which allow users to extract only the necessary data fields from a document. state home health