mongodb - create doc if not exist, else push to array

Question

I have a document in the following form:

{
"_id" : ObjectId("4d2d8deff4e6c1d71fc29a07"),
"user_id" : "714638ba-2e08-2168-2b99-00002f3d43c0",
"events" : [
        {
                "profile" : 10,
                "data" : "....."
        }
        {
                "profile" : 10,
                "data" : "....."
        }
        {
                "profile" : 20,
                "data" : "....."
        }
        ...
   ]
 }

I'd like to have some sort of upsert statement. It needs to add an event to the events array for user_id in case there is already such doc exist, else it needs to create the doc with the event item.

Can that be done?

Javier Ferrero · Accepted Answer · 2016-06-08T17:08:05.910

30

You can do upserts in Mongo, see "Upserts with Modifiers" from the Mongo doc:

You may use upsert with a modifier operation. In such a case, the modifiers will be applied to the update criteria member and the resulting object will be inserted.

The query you need will look like:

db.events.update( { "user_id" : "714638ba-2e08-2168-2b99-00002f3d43c0" }, 
{ $push : { "events" : { "profile" : 10, "data" : "X"}}}, {"upsert" : true});

edited Jun 08 '16 at 17:08

answered Jan 23 '11 at 16:49

Javier Ferrero

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1

Maybe I'm using a different version, but with only true as the last update parameter it doesn't work. I had to put {upsert: true} as the argument. – Artur Carvalho Jul 07 '15 at 10:26
2

@Javier Ferrero Example shows only $push, what about if there are fields like user_type after user_id also has to be updated..? – Kanagavelu Sugumar Feb 01 '17 at 07:09
2

@KanagaveluSugumar, then combine: `{ $set: {...}, $push: {...} }` – Dan Oak Oct 24 '19 at 13:57
3

Note - use $addToSet instead of $push. You probably don't want duplicate elements. – Mike Mar 22 '21 at 13:54
For people using pymongo its `upsert=True` named param style and not json style. – Doctor Jan 04 '22 at 18:35

mongodb - create doc if not exist, else push to array

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