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I have a collection of documents in which some documents have filed
atd
and others have
etd
inside a nested field
voyage_details
, for example:
"_id" : ObjectId("..."),
"voyage_details" : {
"atd" : "15-Mar-21"
"_id" : ObjectId("..."),
"voyage_details" : {
"etd" : "15-Mar-21"
Now, I want to write a mongo aggregation query where I create a new field on the basis of a condition where if a document has the key
atd
in it then I want to add the value of key
atd
in that new field and if that key is not present in the document then add the value of key
etd
in that new field.
I have written an aggregate query like this to add a new field on the basis of
atd
or
etd
whichever of the both is present inside the
voyage_details
object:
"$addFields": {
"sailing_date": {
"$cond": {
"if": { "voyage_details.atd": { "$exists": True } },
"then": "$voyage_details.atd",
"else": "$voyage_details.etd"
Can anyone guide me in writing the correct query to add a new field in my mongo aggregation, so that I can use
atd
or
etd
whichever of the both fields present inside the voyage_details section.
"$addFields": {
"sailing_date": {
"$ifNull": ["$voyage_details.atd", "$voyage_details.etd"]
Output:
/* 1 createdAt:3/15/2021, 3:36:19 PM*/
"_id" : ObjectId("604f319b9ee8b82dd8cd9f3f"),
"voyage_details" : {
"atd" : "15-Mar-21"
"sailing_date" : "15-Mar-21"
/* 2 createdAt:3/15/2021, 3:36:19 PM*/
"_id" : ObjectId("604f319b9ee8b82dd8cd9f40"),
"voyage_details" : {
"etd" : "15-Mar-21"
"sailing_date" : "15-Mar-21"
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