How to change one field in a structure that is part of an array in MongoDB using Node.JS

Question

I have the following records in a collection:

{ 
    id : id_value,
    streams : [
        { a : a_value, b : b_value, c : c_value },
        { a : a_value, b : b_value, c : c_value }, ...
    ]
}

I want to be able to change the c_value of a particular entry in the streams array. I've been using a two step process of doing this, pulling out an entry from the streams array, creating a new entry and adding it back to the streams array. This works, but doesn't seem the most efficient way of accomplishing this. Is there a better approach that I can use? Below is the code that I'm currently using:

db.users.update({id:user},
    {$pull : {streams : {$and : [{a : a_value}, {b : b_value}]}}},
    {w:1}, cb);

new_entry = { a : old_a_value, b : old_b_value, c : new_c_value} 

db.users.update({id:user},
    {$addToSet : {streams : new_entry}}, {w:1}, cb);

Thank You, Gary

Gary Kipnis · Accepted Answer · 2016-05-24 17:48:55Z

1

If more than one field is being matched in the array record, then $elemMatch is required.

When matching just one field of an array record, then below works:

db.users.update(
    { "id": user, "streams.a": a_value},
    { "$set" : { "streams.$.c": new_c_value } },
    { "w": 1}, cb);

When matching more than one field of an array record, then $elemMatch is required as shown below:

db.users.update(
    { "id": user, streams: {$elemMatch : {a:a_value, b:b_value}},
    { "$set" : { "streams.$.c": new_c_value } },
    { "w": 1}, cb);

answered May 24, 2016 at 17:48

Gary Kipnis

7321 gold badge15 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to change one field in a structure that is part of an array in MongoDB using Node.JS

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related