I have two collections in MongoDB; users & challenges.
The structure of the users collection looks like this:
name: "John Doe"
email: "john#doe.com"
progress: [
{
_id : ObjectId("610be25ae20ce4872b814b24")
challenge: ObjectId("60f9629edd16a8943d2cab9b")
completed: true
date_completed: 2021-08-06T12:15:32.129+00:00
}
{
_id : ObjectId("611be24ae32ce4772b814b32")
challenge: ObjectId("60g6723efd44a6941l2cab81")
completed: true
date_completed: 2021-08-07T12:15:32.129+00:00
}
]
date: 2021-08-05T13:06:34.129+00:00
The structure of the challenges collection looks like this:
_id: ObjectId("610be25ae20ce4872b814b24")
section_no: 1
section_name: "Print Statements"
challenge_no: 1
challenge_name: "Hello World!"
default_code: "public class Main {public static void main(String[] args) {}}"
solution: "Hello World!"
What I want to be able to do is find the most recent entry in a particular user's 'progress' array within the users collection and based on that result I want to query the challenges collection to find the next challenge for that user.
So say the most recent challenge entry in that user's 'progress' array is...
{
_id : ObjectId("611be24ae32ce4772b814b32")
challenge: ObjectId("60g6723efd44a6941l2cab81")
completed: true
date_completed: 2021-08-07T12:15:32.129+00:00
}
...which is Section 1 Challenge 2. I want to be able to query the challenges collection to return Section 1 Challenge 3, and if that doesn't exist then return Section 2 Challenge 1.
Apologies if this is worded poorly, I am fairly new to MongoDb and unsure of how to create complex queries in it.
Thanks in advance!
One approach:
[
{ // Unwind all arrays
"$unwind":"$progress"
},
{ // Sort in descending order all documents
"$sort":{
"progress.date_completed":-1
}
},
{ // Group them together again but pick only the most recent array element
"$group":{
"_id":"$_id",
"latestProgress":{
"$first":"$progress"
}
}
},
{ // Join with other collection
"$lookup":{
"from":"challenges",
"localField":"latestProgress.challenge",
"foreignField":"challenge",
"as":"Progress"
}
},
{ // Only pick the first array element (since there will be just one)
"$set":{
"Progress":{
"$first":"$Progress"
}
}
}
]
I have provided a comment for each stage so that it would be easier to understand the idea. I'm not confident it's the best approach but it does work since I have tested.
Just a note that there could be a case where Progress field is missing. In that case there is no such challenge document.
Related
The ReThinkDB docs mention:
Documents can be filtered in a variety of ways—ranges, nested values, boolean conditions, and the results of anonymous functions.
Say I have:
{
name: 'Joe'
orders: [
{
id: 123456,
date: '2016-01-19T09:12:48.898000+00:00'
}
]
}
And I would like to retrieve users who have an order with id 123456 in their orders
Per the docs, I have tried using...
(long list of things cut out, now I've found the actual answer)
But I get no results.
This works too:
r.db('myapp').table('people').filter(function(person) {
return person('orders').map(function(order){
return order('id')
}).contains(123456)
})
Got it:
r.db('myapp').table('people').filter(function(person){
return person("orders").contains(function (order) {
return order('id').eq(123456);
})
})
mongoose scheme:
var restsSchema = new Schema({
name: String,
menu: mongoose.Schema.Types.Mixed
});
simplfied document:
{
name: "Dominos Pizza",
menu:{
"1":{
id: 1,
name: "Plain Pizza",
soldCounter: 0
},
"2":{
id: 2,
name: "Pizza with vegetables",
soldCounter: 0
}
}
}
I'm trying to update the soldCounter when given a single/array of "menu items" (such as "1" or "2" objects in the above document) as followed:
function(course, rest){
rest.markModified("menu.1");
db.model('rests').update({_id: rest._id},{$inc: {"menu.1.soldCounter":1}});
}
once this will work i obviously will want to make it more generic, something like: (this syntax is not working but demonstrate my needs)
function(course, rest){
rest.markModified("menu." + course.id);
db.model('rests').update({_id: rest._id},{$inc:{"menu.+"course.id"+.soldCounter":1}});
}
any one can help with this one?
I looked for an answer but couldn't find nothing regarding the 3rd level.
UPDATE:
Added id to the ducument's subDocument
I think you want add all ids into sub-document, one way you can do as following.
Rest.find({_id: rest._id}, function(err, o) {
// add all ids into sub-document...
Object.keys(o.menu).forEach(function(key) {
o.menu[key].id = key;
});
o.save(function(err){ ... });
});
It seems you want to operate the key in query, I am afraid you cannot do it in this way.
Please refer to the following questions.
Mongodb - regex match of keys for subobjects
MongoDB Query Help - query on values of any key in a sub-object
I use Node.js and MongoDB with monk.js and i want to do the logging in a minimal way with one document per hour like:
final doc:
{ time: YYYY-MM-DD-HH, log: [ {action: action1, count: 1 }, {action: action2, count: 27 }, {action: action3, count: 5 } ] }
the complete document should be created by incrementing one value.
e.g someone visits a webpage first this hour and the incrementation of action1 should create the following document with a query:
{ time: YYYY-MM-DD-HH, log: [ {action: action1, count: 1} ] }
an other user in this hour visits an other webpage and document should be exteded to:
{ time: YYYY-MM-DD-HH, log: [ {action: action1, count: 1}, {action: action2, count: 1} ] }
and the values in count should be incremented on visiting the different webpages.
At the moment i create vor each action a doc:
tracking.update({
time: moment().format('YYYY-MM-DD_HH'),
action: action,
info: info
}, { $inc: {count: 1} }, { upsert: true }, function (err){}
Is this possible with monk.js / mongodb?
EDIT:
Thank you. Your solution looks clean and elegant, but it looks like my server can't handle it, or i am to nooby to make it work.
i wrote a extremly dirty solution with the action-name as key:
tracking.update({ time: time, ts: ts}, JSON.parse('{ "$inc":
{"'+action+'": 1}}') , { upsert: true }, function (err) {});
Yes it is very possible and a well considered question. The only variation I would make on the approach is to rather calculate the "time" value as a real Date object ( Quite useful in MongoDB, and manipulative as well ) but simply "round" the values with basic date math. You could use "moment.js" for the same result, but I find the math simple.
The other main consideration here is that mixing array "push" actions with possible "updsert" document actions can be a real problem, so it is best to handle this with "multiple" update statements, where only the condition you want is going to change anything.
The best way to do that, is with MongoDB Bulk Operations.
Consider that your data comes in something like this:
{ "timestamp": 1439381722531, "action": "action1" }
Where the "timestamp" is an epoch timestamp value acurate to the millisecond. So the handling of this looks like:
// Just adding for the listing, assuming already defined otherwise
var payload = { "timestamp": 1439381722531, "action": "action1" };
// Round to hour
var hour = new Date(
payload.timestamp - ( payload.timestamp % ( 1000 * 60 * 60 ) )
);
// Init transaction
var bulk = db.collection.initializeOrderedBulkOp();
// Try to increment where array element exists in document
bulk.find({
"time": hour,
"log.action": payload.action
}).updateOne({
"$inc": { "log.$.count": 1 }
});
// Try to upsert where document does not exist
bulk.find({ "time": hour }).upsert().updateOne({
"$setOnInsert": {
"log": [{ "action": payload.action, "count": 1 }]
}
});
// Try to "push" where array element does not exist in matched document
bulk.find({
"time": hour,
"log.action": { "$ne": payload.action }
}).updateOne({
"$push": { "log": { "action": payload.action, "count": 1 } }
});
bulk.execute();
So if you look through the logic there, then you will see that it is only ever possible for "one" of those statements to be true for any given state of the document either existing or not. Technically speaking, the statment with the "upsert" can actually match a document when it exists, however the $setOnInsert operation used makes sure that no changes are made, unless the action actually "inserts" a new document.
Since all operations are fired in "Bulk", then the only time the server is contacted is on the .execute() call. So there is only "one" request to the server and only "one" response, despite the multiple operations. It is actually "one" request.
In this way the conditions are all met:
Create a new document for the current period where one does not exist and insert initial data to the array.
Add a new item to the array where the current "action" classification does not exist and add an initial count.
Increment the count property of the specified action within the array upon execution of the statement.
All in all, yes posssible, and also a great idea for storage as long as the action classifications do not grow too large within a period ( 500 array elements should be used as a maximum guide ) and the updating is very efficient and self contained within a single document for each time sample.
The structure is also nice and well suited to other query and possible addtional aggregation purposes as well.
I want to implement search for e-shop. User enters text, and API returns products AND categories which matches search phrase.
How do I get products and categories in one request ?
I'm aware I could do
return Ember.RSVP.hash( {
products: this.store.find("product", {searchTerm: "banana"})
categories: this.store.find("category", {searchTerm: "banana"})
} );
but isn't there a way to do it in a single request in order to have a better performance ?
If you can modify you backend just create a new method for search this.store.find("searchResult", {searchTerm: "banana"})
Where searchresult would be something like
{ searchResult { products: [ ... ], categories: [ ... ] } }
first, a comment. The collection described is simplified, for this question. I'm interesting in understanding how to manipulate a mongo db and get statistics of my data.
Let's say I have a collection with test results. The schema is:
Results {
_id: ObjectId
TestNumber: int
result: String // this contains "pass" or "fail"
// additional data
}
For each test can be many reports, so most likely each TestNumber appears in more than one document.
How can I perform a query which returns this info on the entire collection:
TestNumber | count of result == "pass" | count of result == "fail"
You can use the below aggregation operations pipelined together:
Group all the documents based on their testNumber and the type of
result together, so for every testNumber, we would have two
groups each, one for fail and another for pass, with the count of
documents in each group.
Project a variable "pass" for the group containing the result as
pass, and fail for the other group.
Group together the documents again based on the testNumber, and
push the pass and fail documents into an array.
Project the fields as required.
The Code:
Results.aggregate([
{$group:{"_id":{"testNumber":"$testNumber","result":"$result"},
"count":{$sum:1}}},
{$project:{"_id":0,
"testNumber":"$_id.testNumber",
"result":{$cond:[{$eq:["$_id.result","pass"]},
{"pass":"$count"},
{"fail":"$count"}]}}},
{$group:{"_id":"$testNumber",
"result":{$push:"$result"}}},
{$project:{"testNumber":"$_id","result":1,"_id":0}}
],function(a,b){
// post process
})
Sample Data:
db.collection.insert([
{
"_id":1,
"testNumber":1,
"result":"pass"
},
{
"_id":2,
"testNumber":1,
"result":"pass"
},
{
"_id":3,
"testNumber":1,
"result":"fail"
},
{
"_id":4,
"testNumber":2,
"result":"pass"
}])
Sample o/p:
{ "result" : [ { "pass" : 1 } ], "testNumber" : 2 }
{ "result" : [ { "fail" : 1 }, { "pass" : 2 } ], "testNumber" : 1 }
iterating doc.result will give you the pass count and the number of failed tests for the testNumber.