How to use Document#update in Mongoose?
I'm looking at the example here for Document#update in Mongoose:
http://mongoosejs.com/docs/api.html#document_Document-update
Method signature:
Document#update(doc, options, callback)
Example code:
weirdCar.update({$inc: {wheels:1}}, { w: 1 }, callback);
The documentation says the first parameter should be "doc" but what exactly is doc? I would imagine doc should just be an object that maps keys to new values to be updated (by default $set is used). In the code example they are trying to increment wheels by 1.
Then in the example they pass {w : 1} as options but "w" is not a valid option according to Model.Update. The only valid options should be: safe, upsert, multi, strict.
http://mongoosejs.com/docs/api.html#model_Model.update
Can someone explain the example code provided by Mongoose?
The Mongoose api is based on the underlying MongoDB query structure. In this case, "doc" refers to a criteria for matching certain documents that you want to update. The MongoDB docs explain this very clearly: http://docs.mongodb.org/manual/core/write-operations/#update
So, let's say that you had a 'cars' collection, and you wanted to find all documents (all cars) that had 3 wheels, and increment that value so those cars had 4 wheels. In this case, "doc" is { wheels : 3 }, which returns all three-wheeled cars in the collection. Here is the basic query in the MongoDB shell:
> db.cars.update( { wheels : 3 }, { $inc : { wheels : 1 } } );
In Mongoose, you can add additional parameters for options and a callback function, but that's the basic idea.
The key for me was the correct parameters. You need to supply the callback parameter or call .exec() on the result for it to work.
var Product = mongoose.model('product', mongoose.Schema({
name: String
}));
Product.findById('539dceccc61fa4950b43423a', function (err, product) {
product.update({ name: 'test' }, null, function(err, numberAffected, raw) { });
//or
product.update({ name: 'test' }).exec();
});
It seems to me like the docs are wrong.
Further, some people don't understand the issue here. We're trying to call update on a DOCUMENT. NOT query for the document while performing an update. There's a difference, and it's not very well documented by Mongoose.
Here's what the documentation says: about document.update
example: weirdCar.update({$inc: {wheels:1}}, { w: 1 }, callback);
Parameters: doc <Object> options <Object> callback <Function>
Valid Options same as in Model.update
so lets have a look at Model.updates options...
Model.updates options:
There's nothing there that corresponds with that example... {w : 1} is the error here. Ignore that part.
However, you can use it with or without those options.
So it looks like this without any options
weirdCar.update({$inc: {wheels:1}}, function(err, updated) { // 'updated' is the object: {ok: number, nModified: number, n: number} })