How does mongodb filter the subarrays of a two-dimensional array?

  mongodb, question

The following data structure:
Join me and have a fruit’s Document, which reads:

{
 name: 'apple',
 menu: [
 {
 Title:' with pears'
 },
 {
 Title:' with strawberries'
 }
 ]
 },
 {
 name: 'orange',
 menu: [
 {
 Title:' with pears'
 },
 {
 Title:' with strawberries'
 }
 ]
 }

I want to searchPearWhen, get

{
 name: 'apple',
 menu: [
 {
 Title:' with pears'
 }
 ]
 },
 {
 name: 'orange',
 menu: [
 {
 Title:' with pears'
 }
 ]
 }

In other words, how to clean the sub-arrays of the two-dimensional array?

If title doesn’t repeat, simply do the mapping

Db.test.find ({menu.title ":'with pears' }, {name: 1, "menu.$": 1})

But $ will only give you the first matching array element, so if title is duplicated, you need to use thefilterOperator. For specific usage, refer to the examples in the document.