I come from MySQL world so mongo queries are a bit difficult to make considering I can't really make sense of mongo style queries. I am trying to make a query for finding a string. The problem is from my very primitive knowledge about mongodb queries, the query I made isn't working. I tried it in mongoose as well in mongo shell.
Schema:
mongoose.Schema({
doctorID : String,
patientIDList : Array // array of strings
});
Query Objective:
I want to find a doctor with doctorID and then look inside the patientIDList for an ID xxx. If the patientIDList doesn't contains xxx then add xxx in the list otherwise just add nothing.
Query:
The 2 queries I tried
MyModel.findOne({'doctorID':newAppointment.doctorID}, {'patientIDList' : newAppointment.patientID}, function(err){...});
MyModel.findOne({'doctorID': newAppointment.doctorID, 'patientIDList': newAppointment.patientID}, function(err){...});
What am I doing wrong? How can I make a query?
It's always a bit of challenge to switch from a SQL to NoSQL DB and other way around. What you are trying to do is check if a value exists in an array. If the array is a string array you can simply query for the value in array.
MyModel.findOne({doctorID : newAppointment.doctorID}, {patientIDList :newAppointment.doctorID}, function(err, res){
console.log(err, res);
})
Further read: https://docs.mongodb.com/manual/tutorial/query-documents/#match-an-array-element
Relevant Question: Find document with array that contains a specific value
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I am trying to query an old mongoDB collection in node.js with the native driver.
It uses Legacy UUID as its _id field.
In my code I am using Binary values such as: "2u0kLwUZuEWQvjqOjgQU4g=="
and I want to query the collection with find() operation.
When trying to test it directly with mongoDB I am able to use the following query:
db.getCollection('myCollection').find({_id: BinData(3, "2u0kLwUZuEWQvjqOjgQU4g==")})
to find my item.
But what I need to do is to find multiple items.
So I need to use something like this:
db.getCollection('myCollection').find({_ids: { $in: [BinData(3, "2u0kLwUZuEWQvjqOjgQU4g=="), BinData(3, "3u0kLwUZuEWQvjqOjgQU4g==")...]}})
but it does not seem to work and always returns zero records.
I am not sure why? and what might be the correct way to query multiple Legacy UUIDs?
sorry for the noob question.
I'm trying to write the CRUD endpoints for a Friendship model, which holds two users' IDs.
To create a Friendship the first thing I want to do is check if there is already an instance of that model, which would hold both IDs in any given order, so I wrote:
Friendship.findOne.all({users: [user1.id, user2.id]})
.then(.....
But the server responds with a 500 error: Friendship.findOne.all is not a function
What would be the proper way to do this?
I am assuming that you want to check if both id records/documents are present in your collection or not so for that you use $in operator like this
Friendship.find({id: {$in : [user1.id, user2.id]} })
.then(.....
This will return an array of records if any of id records will be present. And it will return empty array if non of the id records will present in your db
I'm using an ajax request from the front end to load more comments to a post from the back-end which uses NodeJS and mongoose. I won't bore you with the front-end code and the route code, but here's the query code:
Post.findById(req.params.postId).populate({
path: type, //type will either contain "comments" or "answers"
populate: {
path: 'author',
model: 'User'
},
options: {
sort: sortBy, //sortyBy contains either "-date" or "-votes"
skip: parseInt(req.params.numberLoaded), //how many are already shown
limit: 25 //i only load this many new comments at a time.
}
}).exec(function(err, foundPost){
console.log("query executed"); //code takes too long to get to this line
if (err){
res.send("database error, please try again later");
} else {
res.send(foundPost[type]);
}
});
As was mentioned in the title, everything works fine, my problem is just that this is too slow, the request is taking about 1.5-2.5 seconds. surely mongoose has a method of doing this that takes less to load. I poked around the mongoose docs and stackoverflow, but didn't really find anything useful.
Using skip-and-limit approach with mongodb is slow in its nature because it normally needs to retrieve all documents, then sort them, and after that return the desired segment of the results.
What you need to do to make it faster is to define indexes on your collections.
According to MongoDB's official documents:
Indexes support the efficient execution of queries in MongoDB. Without indexes, MongoDB must perform a collection scan, i.e. scan every document in a collection, to select those documents that match the query statement. If an appropriate index exists for a query, MongoDB can use the index to limit the number of documents it must inspect.
-- https://docs.mongodb.com/manual/indexes/
Using indexes may cause increased collection size but they improve the efficiency a lot.
Indexes are commonly defined on fields which are frequently used in queries. In this case, you may want to define indexes on date and/or vote fields.
Read mongoose documentation to find out how to define indexes in your schemas:
http://mongoosejs.com/docs/guide.html#indexes
Is there a way to tell the native MongoDB driver for NodeJS to automatically convert the contents of an _id field into an ObjectID?
Say, in this situation:
db.collection("collection").updateOne({_id: data._id}, data)
It's not that data._id = ObjectID(data.id) is hard, but it's another thing to miss each and every time.
There is no way to do that natively. You can make some function for wrapping your mongo queries where you will check params and if it's "_id" parse it to ObjectId.
I'm trying to do a 'findOne' operation in a model that has an array property and filter the results to only list the item if the string im searching is in that array.
Example:
var AppUser = server.loopback.getModel('AppUser');
AppUser.create({
"name":"juan"
"favoriteLetters":["a","b","c"]
},function(){
AppUser.findOne({where:{favoriteLetters:'a'}},function(error,appUser){
console.log(error,appUser);
});
});
So in this case i want to find a 'appUser' that has a favorite letter 'a'.
Thanks.
As far as I understood, possibility of such kind of a query depends on the underlying datasource and is not supported yet for relational DBs. But should be fine with memory storage or mongodb. More details and syntax for query is here: https://groups.google.com/d/msg/loopbackjs/8c8kw8EMiPU/yev3lsmrTFUJ
For anyone else who lands here, that query in your model is correct (for Mongo anyways).
{where:{favoriteLetters:'a'}
Reference:
Find document with array that contains a specific value