MongoDB missing basic document(object) operators?

[Takis]

Hello @wan ,

Use cases are so many,everytime that you want to edit one embeded document
using a variable key (not literal, for example you didnt know it at pipeline writing time,you found it at pipeline run time) it is a use case.

Every programming language that has hash-maps provides those methods to process those
hash-maps.

Lets say you are in pipeline and you have this

  $$mydoc   = one document
  $$mykey   = one key
  
How to do 

  get("$$mydoc","$$mykey")
  contains?("$$mydoc","$$mykey")
  put("$$mydoc","$$mykey","randomValue")
  remove("$$mydoc","$$mykey")
  ....
  (and all those basic operation on maps that programming languages offer)

I managed to make so far only put,in a fast way using mergeObjects and objectToArray.
But it wasn’t straightforward at all.

For arrays its so easy to do a put it in mongoQL
{"$concatArrays"  ["$$array1" ["$$newmember"]])}
I want something like the above but with embeded documents

If you want to see an use example see this post,where i tried to group an array
using reduce and i couldnt do it.

How to group an array using reduce, without unwind+group?

Thank you for trying to help me,i think its not possible to group an array only by using reduce in mongoql. I will make a new topic,asking about the root of the problem. Thank you alot

ObjectToArray and ArrayToObject are ok if document is small or if you will do it one time.
If you are in a reduce,i cant convert the object to array and back to object at each step.

Its like saying to a Javascript programmer,dont add to an Object make the object array first,add to array,and then back to Object,its too slow to be usable.

Thank you