I want to retrieve the last inserted _id, using mongoose as MongoDB wrapper for node.js. I've found the following tutorial, but I can't change any node modules because the app runs on a public server:
Getting "Last Inserted ID" (hint - you have to hack Mongoose)
Any other ideas? This what I want to do:
Insert new user
Get user's _id value
Set a new session based on user's id
Redirect to /
Thanks!
I'm using mongoose version 1.2.0 and as soon as I created a new instance of a mongoose model, the _id is already set.
coffee> u = new User()
[object Object]
coffee> u._id
4dd68fc449aaedd177000001
I also verified that after I call u.save() the _id remains the same. I verified via MongoHub that this is indeed the real ID saved into MongoDB.
If you explicitly declare
_id: Schema.ObjectId
for your model, then the ObjectId will not be available after new or save.
This is probably a bug.
If you're looking to get the last inserted _id of a sub object, then create the object, and add it to the item. Here's an example in NowJS using MongoDB and Mongoose (to add some schema sugar) which then converts the result to JSON to send back to the client:
var nowRoomID = this.now.room;
var Conversation = mongoose.model('Conversation');
Conversation.findById(convID, function(error, conversation) {
var Blip = mongoose.model('Blip');
var createdBlip = new Blip();
createdBlip.author= nowUserName;
createdBlip.authorid = parsed.authorid;
createdBlip.body = revisedText;
createdBlip.created_at = new Date();
createdBlip.modified_at = new Date();
conversation.blips.push(createdBlip);
parsed._id = createdBlip._id; //NOTE: ID ACCESSED HERE
message = JSON.stringify(parsed);
conversation.save(function (err) {
if (!err) {
console.log('Success - saved a blip onto a conversation!');
nowjs.getGroup(nowRoomID).now.receiveMessage(nowUserName, message);
}
});
With MongoDB, if you don't explicitly set a document's _id value then the client driver will automatically set it to an ObjectId value. This is different from databases that might generate IDs on the server and need another query to retrieve it, like with SQL Server's scope_identity() or MySQL's last_insert_id().
This allows you to insert data asynchronously because don't need to wait for the server to return an _id value before you continue.
So, as shown is Peter's answer, the _id is available before the document is saved to the database.
I just get the id from the document passed to the callback, since save returns the saved document.
Check below url
http://mongodb.github.io/node-mongodb-native/markdown-docs/insert.html
you will find following code in given url
var document = {name:"David", title:"About MongoDB"};
collection.insert(document, {w: 1}, function(err, records){
console.log("Record added as "+records[0]._id);
});
Related
People register for an event. There are two collections in the database. One for new registrations coming in and one for the registrations of previous years. Both contain an email field as unique identifier.
I would like to know if its possible to check if a newly registered person has registered before in previous years. If so add a field, for example: returningCustomer: true. Otherwise add returningCustomer: false
I am using Mongoose and have a User model for new registrations. I don't have a model (yet) for previously registered users. Would that be neccesary? If it is possible to check if a person has registered before and a field can be added before saving, it might be handy to save the user to the returning customers collection immediatly as well.
I know it is possible to access the current document and collection using a pre save hook, but how about doing a lookup in another collection, write a bit of logic and add a field to the current document pre save?
userSchema.pre('save', function (doc, next) {
const exists = otherCollection.find({ email: doc.email });
exists ? doc.returningCustomer = true : doc.returningCustomer = false;
next();
});
You should have a model for the collection you want to lookup.
Then you can query the other collection before saving the current collection.
CurrentModel.pre('save', async function (next) {
const doc = await OtherModel.find({ field: this.field });
doc.length ? this.returningCustomer = false : this.returningCustomer = true;
next();
});
I have two collections A + B. Both are created at the same event. B is created some lines before A. Now I need to store in A the _id of B. How do I get the id of the just created B?
I am new to meteor and mongoDB, is the _id internally passed back on creation so that it is already available (I did not find an indication for this) or do I need to reread B? If so how do I do this best?
EDIT
I understand that the _id is passed back on the server after the insert.
Client:
Meteor.call('addB',b );
Server:
'addB':function(b){
return B.insert(b);
},
How can I pass B._id to the client so that I can do, on the client, something like:
a.id_of_B = B._id
Meteor.call('addA',a );
collection.insert returns the value of the created _id field. The docs says "Returns its unique _id.".
To return the values to the client a simple callback can be used:
Here again the link to the docs collection.insert
Client:
Meteor.call('addB',b function(error, result) {
BId = result;
});
Server:
'addB':function(b){
return B.insert(b);
},
Remember that in general you don't need Meteor.call() to insert into a collection. You can do both inserts on the client (if the collections are available there) and these inserts will automatically be synchronized back to the server.
var a = {...}; // some object
var b = {...}; // some other object
B.insert(b,function(err,id){ // asynchronous style
a.idOfB = id;
A.insert(a);
})
a.idOfB = B.insert(b); // synchronous style
A.insert(a);
When I use mongo-ruby-driver and I insert new document it returns generated '_id':
db = MongoClient.new('127.0.0.1', '27017').db('ruby-mongo-examples')
id = db['test'].insert({name: 'example'})
# BSON::ObjectId('54f88b01ab8bae12b2000001')
I'm trying to get the '_id' of a document after doing an insertion using Moped:
db = Moped::Session.new(['127.0.0.1:27017'])
db.use('ruby-mongo-examples')
id = db['coll'].insert({name: 'example'})
# {"connectionId"=>15, "n"=>0, "syncMillis"=>0, "writtenTo"=>nil, "err"=>nil, "ok"=>1.0}
How I get the id using Moped?
Update:
I also try use safe mode but it doesn't work:
db = Moped::Session.new(['127.0.0.1:27017'])
db.use('ruby-mongo-examples')
db.with(safe: true) do |safe|
id = safe['coll'].insert({name: 'example'})
# {"connectionId"=>5, "n"=>0, "syncMillis"=>0, "writtenTo"=>nil, "err"=>nil, "ok"=>1.0}
end
After inserting/saving, the returned object will have a property inserted_id which is a BSON::ObjectId:
# I'm using insert_one
result = safe['coll'].insert_one({name: 'example'})
result.methods.sort # see list of methods/properties
result.inserted_id
result.inserted_id.to_s # convert to string
From this issue:
It would be nice, but unfortunately Mongo doesn't give us anything
back when inserting (since it's fire and forget), and when in safe
mode it still doesn't give the id back if it generated it on the
server. So there really isn't any possible way for us to do this
unless it was a core feature in MongoDB.
Your best bet would be to generate the id before inserting the document:
document = { _id: Moped::BSON::ObjectId.new, name: "example" }
id = document[:_id]
I'm trying to add data to my mongo database with mongoose, but there is a high probability that most of the data is already in the database, only a small number of fields need to be updated. Creation time for the record and last time updated need to be saved.
My first attempt at solving this problem included using the Model.save function, given that my model is called server, and data is an object coming from an external http service, which specifies the unique _id in data.
var instance = new Server(data);
instance.save(function(err){
if(err)
console.log(err);
});
also my pre-save hook:
ServerSchema.pre('save', function(next) {
this.lastseen = Date.now();
if (!this.isNew)
return next() //if the entry isn't new, lets not change the date registred
this.registered = Date.now();
next() //Don't forget this!
})
The problem here is that on duplicate _id the save chokes, with error E11000 duplicate key error index...
This now makes sense as save only does an update when the document instance is not created using the new operator.
So in my next attempt, I added code to attempt to lookup the document, then used underscore.js's _.extend to merge the new document with the one found in the database, then saved that to the database. The problem with this approach is that it require an extra call to the database for each chunk of data being processed.
My third attempt uses the Model.findByIdAndUpdate with {upsert:true} this works, in terms of stroring the data in the database, but schema defaults and my pre-save hook isn't triggered.
The fourth attempt uses code suggested by #aheckmann in this gist: https://gist.github.com/2764948
var server = new Server();
server.init(ping);
server.save(function(err){
if(err) {
console.log("DB Error: ",err);
return res.send('DB Error')
}
//if server approved, tell the inworld server to sync textures
if(server.approved)
res.send('success')
else
res.send('skip')
user.servers.addToSet(ping._id); //add the server to the user's list
user.save(function(err, usr){
if(err)
console.log("DB Error: ", err);
})
})
Here again, the pre-save hook isn't triggered. Am I to understand that the only to upsert with hooks is to attempt to find the document first with a findById ?
Q:
Is there a way to "upsert" Insert or Update based on the primary unique key without making more than one database call per chunk of data? Is there a method, or obvious fact that I am overlooking?
I don't think that you can do it with less then two calls to DB, unless you'll drop mongoose part and use mongo driver directly. But you can create a static method to do all the job for you:
ServerSchema.statics.findOrCreate(function(doc, next) {
this.findById(doc._id, function(err, res) {
res || (res = new this);
_.extend(res, doc); // add new data to the document
next(err, res); // if (err != null) then something went wrong
});
});
findByIdAndUpdate not triggers presave hook because it calls mongo driver directly.
I need to iterate through all of the collections in my MongoDB database and get the time when each of the collections was created (I understand that I could get the timestamp of each object in the collection, but I would rather not go that route if a simpler/faster method exists).
This should give you an idea of what I'm trying to do:
MongoDatabase _database;
// code elided
var result = _database.GetAllCollectionNames().Select(collectionName =>
{
_database.GetCollection( collectionName ) //.{GetCreatedDate())
});
As far as I know, MongoDB doesn't keep track of collection creation dates. However, it's really easy to do this yourself. Add a simple method, something like this, and use it whenever you create a new collection:
public static void CreateCollectionWithMetadata(string collectionName)
{
var result = _db.CreateCollection(collectionName);
if (result.Ok)
{
var collectionMetadata = _db.GetCollection("collectionMetadata");
collectionMetadata.Insert(new { Id = collectionName, Created = DateTime.Now });
}
}
Then whenever you need the information just query the collectionMetadata collection. Or, if you want to use an extension method like in your example, do something like this:
public static DateTime GetCreatedDate(this MongoCollection collection)
{
var collectionMetadata = _db.GetCollection("collectionMetadata");
var metadata = collectionMetadata.FindOneById(collection.Name);
var created = metadata["Created"].AsDateTime;
return created;
}
The "creation date" is not part of the collection's metadata. A collection does not "know" when it was created. Some indexes have an ObjectId() which implies a timestamp, but this is not consistent and not reliable.
Therefore, I don't believe this can be done.
Like Mr. Gates VP say, there is no way using the metadata... but you can get the oldest document in the collection and get it from the _id.
Moreover, you can insert an "empty" document in the collection for that purpose without recurring to maintain another collection.
And it's very easy get the oldest document:
old = db.collection.find({}, {_id}).sort({_id: 1}).limit(1)
dat = old._id.getTimestamp()
By default, all collection has an index over _id field, making the find efficient.
(I using MongoDb 3.6)
Seems like it's some necroposting but anyway: I tried to find an answer and got it:
Checked it in Mongo shell, don't know how to use in C#:
// db.payload_metadata.find().limit(1)
ObjectId("60379be2bec7a3c17e6b662b").getTimestamp()
ISODate("2021-02-25T12:45:22Z")