Update and/or add array element properties using req.body via Mongoose?

Question

I have the following document:

{
    "_id" : ObjectId("503b83dfad79cc8d26000004"),
    "pdfs" : [
        {
            "title" : "Test document",
            "pdf_id" : ObjectId("504f6793ce351a595d000004"),
            "created_at" : ISODate("2012-09-11T16:32:19.276Z")
        },
        {
            "title" : "Some other doc",
            "pdf_id" : ObjectId("502bf124b4642341230003f0"),
            "created_at" : ISODate("2012-09-11T11:34:19.276Z")
        }
    ]
}

Now in an incoming form via req.body, I have 2 fields: title and description.

I want to update title and insert description for a specified pdf_id, how do I do that?

So in the end, my document will now look like:

{
    "_id" : ObjectId("503b83dfad79cc8d26000004"),
    "pdfs" : [
        {
            "title" : "This is an UPDATED title",
            "description" : "It has an ALL NEW description",
            "pdf_id" : ObjectId("504f6793ce351a595d000004"),
            "created_at" : ISODate("2012-09-11T16:32:19.276Z")
        },
        {
            "title" : "Some other doc",
            "pdf_id" : ObjectId("502bf124b4642341230003f0"),
            "created_at" : ISODate("2012-09-11T11:34:19.276Z")
        }
    ]
}

Just to be clear, I'm really just looking for the Mongoose update syntax.

JohnnyHK · Accepted Answer · 2012-09-11 17:29:21Z

9

You can use the $ positional operator to refer to the matched pdfs array element in your $set:

Model.update(
    { 'pdfs.pdf_id': pdf_id }, 
    { $set: { 
        'pdfs.$.title': title, 
        'pdfs.$.description': description 
    }}, function (err, numAffected) { ... }
);

answered Sep 11, 2012 at 17:29

JohnnyHK

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3 Comments

k00k Over a year ago

In the $set, is there any way to assign those properties dynamically? The user may not supply some, and I'd prefer to not have to specify them explicitly.

JohnnyHK Over a year ago

Sure, you'd just need to build up that $set object programmatically and then pass that object in as the second parameter to the update call. Sort of like in this other question: stackoverflow.com/questions/12184626/…

k00k Over a year ago

Cool, thanks. Something that tripped me up, that might help others: It wouldn't update for me when I just had my array set to mixed []. I had to built out the schema for the array and make sure that the _id of the array element you're trying to update is specified as a type: Schema.Types.ObjectId in your schema.

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