I'm having a lot of trouble getting query results for certain collections in Meteor.
I have set
idGeneration : 'MONGO'
in the collection definitions, and in the mongo shell these collections look like this :
the document i want, call it documentW (from CollectionA) = {
"_id" : ObjectId("7032d38d35306f4472844be1"),
"product_id" : ObjectId("4660a328bd55247e395edd23"),
"producer_id" : ObjectId("a5ad120fa9e5ce31926112a7") }
documentX (from collection "Products") = {
_id : ObjectId("4660a328bd55247e395edd23")
}
documentY (from collection "Producers") = {
_id : ObjectId("a5ad120fa9e5ce31926112a7")
}
If i run a query like this in Meteor
CollectionA.findOne({ product_id : documentX._id, producer_id : documentY._id})
I'm expecting to get my documentW back... but I get nothing.
When I run this query in the mongo shell
db.collectiona.find({ product_id : ObjectId("4660a328bd55247e395edd23"), producer_id :
ObjectId("a5ad120fa9e5ce31926112a7") })
I get my documentW back no problem.
Of course in Meteor if I call
console.log(documentX._id)
I get this
{ _str : "4660a328bd55247e395edd23" }
Anyone have any ideas what is going on here ? I have tried all kinds of things like
Meteor.Collection.ObjectID(documentX._id._str)
but the search still returns empty...
Running the latest 0.7.0.1 version of Meteor...
I don't know if this answers your question, but I can't put this code in a comment. This code is working for me, trying to follow what I believe you are trying to do:
Products = new Meteor.Collection("products", {
idGeneration: "MONGO"
});
Producers = new Meteor.Collection("producers", {
idGeneration: "MONGO"
});
CollectionA = new Meteor.Collection("a", {
idGeneration: "MONGO"
});
Products.insert({
foo: "bar"
});
Producers.insert({
fizz: "buzz"
});
var documentX = Products.findOne();
var documentY = Producers.findOne();
CollectionA.insert({
product_id: documentX._id,
producer_id: documentY._id
});
var documentW = CollectionA.findOne({
product_id: documentX._id,
producer_id: documentY._id
});
console.log(documentW); // This properly logs the newly created document
This is on 0.7.0.1. Do you see anything in your code that diverges from this?
Related
I have the following Document:
{
"_id": 100,
"Version": 1,
"Data": "Hello"
}
I have a function which return a number from a sequence:
function getNextSequence(name) {
var ret = db.Counter.findAndModify(
{
query: { _id: name },
update: { $inc: { value: 1 } },
new: true,
upsert: true
}
);
return ret.value;
}
I can use this for optimistic concurrency by performing the following Mongo command:
db.CollectionName.findAndModify({
query: { "_id" : NumberLong(100), "Version" : 1 },
update: { "$set" : {
"Data": "Here is new data!",
"Version" : db.eval('getNextSequence("CollectionName")') }
},
new: true
}
);
This will update the document (as the _id and Version) match, with the new Data field, and also the new number out of the eval call.
It also returns a modified document, from which I can retrieve the new Version value if I want to make another update later (in the same 'session').
My problem is:
You cannot create an Update document using the MongoDB C# client that will serialize to this command.
I used:
var update = Update.Combine(
new UpdateDocument("$set", doc),
Update.Set(versionMap.ElementName, new BsonJavaScript("db.eval('getNextSequence(\"Version:CollectionName\")')")))
);
If you use what I first expected to perform this task, BsonJavascript, you get the following document, which incorrectly sets Version to a string of javascript.
update: { "$set" : {
"Data": "Here is new data!",
"Version" : { "$code" : "db.eval('getNextSequence(\"Version:CollectionName\")')" }
}
}
How can I get MongoDB C# client to serialize an Update document with my db.eval function call in it?
I have tried to add a new BsonValue type in my assembly which I would serialize down to db.eval(''); However there is a BsonType enum which I cannot modify, without making a mod to MongoDB which I would not like to do incase of any issues with the change, compatibility etc.
I have also tried simply creating the Update document myself as a BsonDocument, however FindAndModify will only accept an IMongoUpdate interface which a simply a marker that at present I find superfluous.
I have just tried to construct the command manually by creating a BsonDocument myself to set the Value: db.eval, however I get the following exception:
A String value cannot be written to the root level of a BSON document.
I see no other way now than drop down to the Mongo stream level to accomplish this.
So I gave up with trying to get Mongo C# Client to do what I needed and instead wrote the following MongoDB function to do this for me:
db.system.js.save(
{
_id : "optimisticFindAndModify" ,
value : function optimisticFindAndModify(collectionName, operationArgs) {
var collection = db.getCollection(collectionName);
var ret = collection.findAndModify(operationArgs);
return ret;
}
}
);
This will get the collection to operate over, and execute the passed operationArgs in a FindAndModify operation.
Because I could not get the shell to set a literal value (ie, not a "quoted string") on a javascript object, I had to to this in my C# code:
var counterName = "Version:" + CollectionName;
var sequenceJs = string.Format("getNextSequence(\"{0}\")", counterName);
var doc = entity.ToBsonDocument();
doc.Remove("_id");
doc.Remove(versionMap.ElementName);
doc.Add(versionMap.ElementName, "SEQUENCEJS");
var findAndModifyDocument = new BsonDocument
{
{"query", query.ToBsonDocument()},
{"update", doc},
{"new", true},
{"fields", Fields.Include(versionMap.ElementName).ToBsonDocument() }
};
// We have to strip the quotes from getNextSequence.
var findAndModifyArgs = findAndModifyDocument.ToString();
findAndModifyArgs = findAndModifyArgs.Replace("\"SEQUENCEJS\"", sequenceJs);
var evalCommand = string.Format("db.eval('optimisticFindAndModify(\"{0}\", {1})');", CollectionName, findAndModifyArgs);
var modifiedDocument = Database.Eval(new EvalArgs
{
Code = new BsonJavaScript(evalCommand)
});
The result of this is that I can now call my Sequence Javascript, the getNextSequence function, inside the optimisticFindAndModify function.
Unforunately I had to use a string replace in C# as again there is no way of setting a BsonDocument to use the literal type db.eval necessary, although Mongo Shell likes it just fine.
All is now working.
EDIT:
Although, if you really want to push boundaries, and are actually awake, you will realize this same action can be accomplished by performing an $inc on the Version field.... and none of this is necessary....
However: If you want to follow along to the MongoDB tutorial on how they to say to implement concurrency, or you just want to use a function in a FindAndModify, this will help you. I know I'll probably refer back to it a few times in this project!
I'm dont think that this is a Meteor specific question, but rather around mongo and building mongo queries.
If I have the following structure,
{
username : someName,
contacts : [
{
userid : asdfae33rtqqxxx,
name : contactName,
status : friend
}
{
userid : asdfae33rtqqxxx,
name : anotherName,
status : pending
}
{
userid : asdfae33rtqqxxx,
name : contactName,
status : blocked
}
]
}
How could I pass in values from this array into a query against the users collection, to a) get the users in this array, or b) get all users in this array from the users collection with a particular status.
If this is not possible, how should I adjust my schema in order to make these sorts of queries possible?
This function will return a Meteor.users cursor based on an array of contacts and an optionally required status:
var usersByContacts = function(contacts, requiredStatus) {
var userIds = _.chain(contacts)
.map(function(c) {
if (requiredStatus) {
if (c.status === requiredStatus)
return c.userid;
} else {
return c.userid;
}
})
.compact()
.value();
return Meteor.users.find({_id: {$in: userIds}});
};
You can use it like this:
var users1 = usersByContacts(thing.contacts);
var users2 = usersByContacts(thing.contacts, 'pending');
This assumes thing has the schema referenced in your question. Also note that if you find this is a common pattern in your code, you should consider turning usersByContacts into a transform.
I'm running this code in a mongodb console:
var participantsWithoutCategory = db.participant.find({eventId: ObjectId("536d5564e7b237df30b628cc"), category: {$exists: false}});
var event = db.event.find({_id: ObjectId("536556c4eaa237df30b628cc")});
participantsWithoutCategory.forEach(function (entry) {
var userId = new ObjectId("" + entry._id + "");
var user = db.user.find( { _id: userId} );
print("got user: " + user);
});
and the result of the prints is:
got user: DBQuery: Oc5mjdKkhyDb3r6rhnzw.user -> { "_id" : ObjectId("536d8586ebb237df30b62bcb") }
so I'm just wondering how to get the actual object rather than a pointer to it?
if I try to get any of its properties such as user.dob I get a null :(
Turns out that's how mongo says that the query had no results... I've fixed it by using the right property of the object and not the _id but that's beyond the point.
The interesting thing here is that mongo gives back the DBQuery when find() returns nothing.
I'm using meteor 0.3.7 in Win7(32) and trying to create a simple logging system using 2 MongoDB collections to store data that are linked by DBRef.
The current pseudo schema is :
Users {
username : String,
password : String,
created : Timestamp,
}
Logs {
user_id : DBRef {$id, $ref}
message : String
}
I use server methods to insert the logs so I can do some upserts on the clients collection.
Now I want to do an old "left join" and display a list of the last n logs with the embedded User name.
I don't want to embed the Logs in Users because the most used operation is getting the last n logs. Embedding in my opinion was going to have a big impact in performance.
What is the best approach to achieve this?
Next it was great if possible to edit the User name and all items change theis name
Regards
Playing around with Cursor.observe answered my question. It may not be the most effective way of doing this, but solves my future problems of derefering DBRefs "links"
So for the server we need to publish a special collection. One that can enumerate the cursor and for each document search for the corresponding DBRef.
Bare in mind this implementation is hardcoded and should be done as a package like UnRefCollection.
Server Side
CC.Logs = new Meteor.Collection("logs");
CC.Users = new Meteor.Collection("users");
Meteor.publish('logsAndUsers', function (page, size) {
var self = this;
var startup = true;
var startupList = [], uniqArr = [];
page = page || 1;
size = size || 100;
var skip = (page - 1) * size;
var cursor = CC.Logs.find({}, {limit : size, skip : skip});
var handle = cursor.observe({
added : function(doc, idx){
var clone = _.clone(doc);
var refId = clone.user_id.oid; // showld search DBRefs
if (startup){
startupList.push(clone);
if (!_.contains(uniqArr, refId))
uniqArr.push(refId);
} else {
// Clients added logs
var deref = CC.Users.findOne({_id : refid});
clone.user = deref;
self.set('logsAndUsers', clone._id, clone);
self.flush();
}
},
removed : function(doc, idx){
self.unset('logsAndUsers', doc._id, _.keys(doc));
self.flush();
},
changed : function(new_document, idx, old_document){
var set = {};
_.each(new_document, function (v, k) {
if (!_.isEqual(v, old_document[k]))
set[k] = v;
});
self.set('logsAndUsers', new_document._id, set);
var dead_keys = _.difference(_.keys(old_document), _.keys(new_document));
self.unset('logsAndUsers', new_document._id, dead_keys);
self.flush();
},
moved : function(document, old_index, new_index){
// Not used
}
});
self.onStop(function(){
handle.stop();
});
// Deref on first Run
var derefs = CC.Users.find({_id : {$in : uniqArr} }).fetch();
_.forEach(startupList, function (item){
_.forEach(derefs, function(ditems){
if (item["user_id"].oid === ditems._id){
item.user = ditems;
return false;
}
});
self.set('logsAndUsers', item._id, item);
});
delete derefs; // Not needed anymore
startup = false;
self.complete();
self.flush();
});
For each added logs document it'll search the users collection and try to add to the logs collection the missing information.
The added function is called for each document in the logs collection in the first run I created a startupList and an array of unique users ids so for the first run it'll query the db only once. Its a good idea to put a paging mechanism to speed up things.
Client Side
On the client, subscribe to the logsAndUsers collection, if you want to make changes do it directly to the Logs collection.
LogsAndUsers = new Meteor.collection('logsAndUser');
Logs = new Meteor.colection('logs'); // Changes here are observed in the LogsAndUsers collection
Meteor.autosubscribe(function () {
var page = Session.get('page') || 1;
Meteor.subscribe('logsAndUsers', page);
});
Why not just also store the username in the logs collection as well?
Then you can query on them directly without needing any kind of "join"
If for some reason you need to be able to handle that username change, you just fetch the user object by name, then query on Logs with { user_id : user._id }
I'm using meteor 0.3.7 in Win7(32) and trying to create a simple logging system using 2 MongoDB collections to store data that are linked by DBRef.
The current pseudo schema is :
Users {
username : String,
password : String,
created : Timestamp,
}
Logs {
user_id : DBRef {$id, $ref}
message : String
}
I use server methods to insert the logs so I can do some upserts on the clients collection.
Now I want to do an old "left join" and display a list of the last n logs with the embedded User name.
I don't want to embed the Logs in Users because the most used operation is getting the last n logs. Embedding in my opinion was going to have a big impact in performance.
What is the best approach to achieve this?
Next it was great if possible to edit the User name and all items change theis name
Regards
Playing around with Cursor.observe answered my question. It may not be the most effective way of doing this, but solves my future problems of derefering DBRefs "links"
So for the server we need to publish a special collection. One that can enumerate the cursor and for each document search for the corresponding DBRef.
Bare in mind this implementation is hardcoded and should be done as a package like UnRefCollection.
Server Side
CC.Logs = new Meteor.Collection("logs");
CC.Users = new Meteor.Collection("users");
Meteor.publish('logsAndUsers', function (page, size) {
var self = this;
var startup = true;
var startupList = [], uniqArr = [];
page = page || 1;
size = size || 100;
var skip = (page - 1) * size;
var cursor = CC.Logs.find({}, {limit : size, skip : skip});
var handle = cursor.observe({
added : function(doc, idx){
var clone = _.clone(doc);
var refId = clone.user_id.oid; // showld search DBRefs
if (startup){
startupList.push(clone);
if (!_.contains(uniqArr, refId))
uniqArr.push(refId);
} else {
// Clients added logs
var deref = CC.Users.findOne({_id : refid});
clone.user = deref;
self.set('logsAndUsers', clone._id, clone);
self.flush();
}
},
removed : function(doc, idx){
self.unset('logsAndUsers', doc._id, _.keys(doc));
self.flush();
},
changed : function(new_document, idx, old_document){
var set = {};
_.each(new_document, function (v, k) {
if (!_.isEqual(v, old_document[k]))
set[k] = v;
});
self.set('logsAndUsers', new_document._id, set);
var dead_keys = _.difference(_.keys(old_document), _.keys(new_document));
self.unset('logsAndUsers', new_document._id, dead_keys);
self.flush();
},
moved : function(document, old_index, new_index){
// Not used
}
});
self.onStop(function(){
handle.stop();
});
// Deref on first Run
var derefs = CC.Users.find({_id : {$in : uniqArr} }).fetch();
_.forEach(startupList, function (item){
_.forEach(derefs, function(ditems){
if (item["user_id"].oid === ditems._id){
item.user = ditems;
return false;
}
});
self.set('logsAndUsers', item._id, item);
});
delete derefs; // Not needed anymore
startup = false;
self.complete();
self.flush();
});
For each added logs document it'll search the users collection and try to add to the logs collection the missing information.
The added function is called for each document in the logs collection in the first run I created a startupList and an array of unique users ids so for the first run it'll query the db only once. Its a good idea to put a paging mechanism to speed up things.
Client Side
On the client, subscribe to the logsAndUsers collection, if you want to make changes do it directly to the Logs collection.
LogsAndUsers = new Meteor.collection('logsAndUser');
Logs = new Meteor.colection('logs'); // Changes here are observed in the LogsAndUsers collection
Meteor.autosubscribe(function () {
var page = Session.get('page') || 1;
Meteor.subscribe('logsAndUsers', page);
});
Why not just also store the username in the logs collection as well?
Then you can query on them directly without needing any kind of "join"
If for some reason you need to be able to handle that username change, you just fetch the user object by name, then query on Logs with { user_id : user._id }