MongoDB - Query on the last element of an array?

Question

I know that MongoDB supports the syntax find{array.0.field:\"value\"}, but I specifically want to do this for the last element in the array, which means I don\'

Answer 1

You can use $expr ( 3.6 mongo version operator ) to use aggregation functions in regular query.

Compare query operators vs aggregation comparison operators.

For scalar arrays

db.col.find({$expr: {$gt: [{$arrayElemAt: ["$array", -1]}, value]}})

For embedded arrays - Use $arrayElemAt expression with dot notation to project last element.

db.col.find({$expr: {$gt: [{"$arrayElemAt": ["$array.field", -1]}, value]}})

Spring @Query code

@Query("{$expr:{$gt:[{$arrayElemAt:[\"$array\", -1]}, ?0]}}")
ReturnType MethodName(ArgType arg);