multiple mongo update operator in a single statement

Question

Can i combine $pushAll and $inc in one statement ?

Before combine, this works fine :

db.createCollection("test");
db.test.insert({"name" : "albert", "bugs" : []});

db.test.update({"name":"albert"}, 
    {"$pushAll" : {"bugs" : [{"name":"bug1", "count":1}]}});

db.test.update({"name":"albert"}, 
    {"$inc" : {"bugs.0.count" : 1}});

db.test.update({"name":"albert"}, 
    {"$pushAll" : {"bugs" : [{"name":"bug2", "count":1}]}});

But when i try combining it like this :

db.createCollection("test");
db.test.insert({"name" : "albert", "bugs" : []});

db.test.update({"name":"albert"}, 
    {"$pushAll" : {"bugs" : [{"name":"bug1", "count":1}]}});

db.test.update({"name":"albert"}, 
    {
       "$pushAll" : {"bugs" : [{"name":"bug2", "count":1}]}, 
       "$inc" : {"bugs.0.count" : 1}
    }
);

This error happens :

have conflicting mods in update

Answer 1

It should be taken care that the updates should not conflict with each other while performing multiple updates on the same document.

As the problem is that   "$push" : {"bugs" : [{"name":"bug1", "count":1}]} and "$inc" : {"bugs.0.count" : 1} are parallely trying to update the same section”bugs” array ,therefore they all conflicts.

So this can be achieved if multiple updates are modifying different sections of a document at a particular instance as:

> db.test.drop()

true

> db.test.save({ "_id" : 1, "name" : "albert", "bugs" : [ ] })

> db.test.update({"name":"albert"}, {"$pushAll" : {"bugs" : [{"name":"bug1", "count":1}]}, "$inc" : {"increment" : 1}, $set:{"note":"Here is another field."}})

> db.test.find()

{ "_id" : 1, "bugs" : [ { "name" : "bug1", "count" : 1 } ], "increment" : 1, "name" : "albert", "note" : "Here is another field." }.

For more updates check out the MongoDB tutorial by Intellipaat.