mongodb/learnmongodbthehardway

Mahendra Sure

@MahendraSure

i can do update the document upto two levels deep using $push operator

is any other way to update the document of this kind

jatin goel

@jatingoel018_twitter

I have a question. Mongo 3.6 provides document level locking. And it uses multiple granularity locks. Now if update request comes in, it will try to get IX lock on db ,then IX lock on Collection and then it will search for all the matching docs and will acquire X lock on them but if it fails it will go to queue and retry. But this problem can come again and again

How it is handled ?

Akshay Iyer

@AkshayIyer12

I had a doubt!

I was exploring $group.

I wanted to match the data by a specific customer and then group by status and then group by priority on each status ( And retain the data from 1st grouping as well).

Tanmay Verma

@tanmay.cs_gitlab

Helllooo

my product collection is like:

db.product.insert({
    name: "shirt",
    translations: [
          {
              language: "fr",
              name: "chemise"
          },
          {
              language: "es",
              name: "camisa"
          }
   ]
});

I need a query so that I will get: { name: camisa }

if the language is "es"

Juha Lindstedt

@pakastin

{ ’translations.language’: ’es’, ’translations.name’: ’camisa’ } 😉

Christian Amor Kvalheim

@christkv

if you want to pull up only the spanish field one possible way (might be others) is to do

db.t.aggregate([{$match: {name: "shirt"}}, {$unwind: "$translations"}, {$match: {"translations.language": "es"}}, {$project: {"name": "$translations.name"}}]).pretty()

that returns a document with the field name in it

that is the spanish translation

Tanmay Verma

@tanmay.cs_gitlab

Thank you so much!! :)

Bexanderthebex

@Bexanderthebex

I am currently facing a problem in mongodb wherein, I can successfully insert a document based on a model from mongoose repeatedly despite the contraints. I am using docker to contain the mongodb image

Additionally, when I connect to the mongo shell of the said docker image, wehn I query the inserted document, there seems to be no result but I can see the db and the collection established

xpol

@xpol

http://learnmongodbthehardway.com/schema/schemabasics/ In the last paragraph of Embedding session, it says:

The third problem is exposed when one tries to perform pagination of the comments. There is no way to limit the comments returned from the Blog Post using normal finds so we will have to retrieve the whole blog document and filter the comments in our application.

But there is $slice for that: db.posts.find( {}, { comments: { $slice: [ 20, 10 ] } } ). Am I wrong?

Jordi Pinyana

@jordipainan

Hello !! Has anyone worked with mongo Rust driver ? Or if u know another room related, i need to ask something related to save() method on the mongodb rust crate

thank you

nsharma098

@nsharma098

    "_id" : 137,
    "name" : "Tamika Schildgen",
    "scores" : [
        {
            "type" : "exam",
            "score" : 4.433956226109692
        },
        {
            "type" : "quiz",
            "score" : 65.50313785402548
        },
        {
            "type" : "homework",
            "score" : 89.5950384993947
        }
    ]
}

How can i remove lowest score of type homework

flurt

@flurt

I'm trying to write mongodb schema for a CMS i'm working on, and i have a User model/schema that contains the password of the user and email etc, i wonder if i should separate an Author model for his/her authentication model?

s/for/from

scientronic92

@scientronic92

Hi guys,

I just have an issue with installing mongodb compass community on ubuntu 18.04, I downloaded several versions but when I open it, it start loading then disappear

If it will not work forever, do you suggest using pycharm with pymongo or NoSQLBooster for mongodb?

Christian Amor Kvalheim

@christkv

Just posted a new article http://learnmongodbthehardway.com/article/transactions/

Shanon Jackson

@ShanonJackson

Mmmmmmm trying to learn MongoDB on a side project wondering if any expert can lend some advice on how to structure this data.

My user has some listings stored on his document -> the listings are a listing of an "Item"
Items are part of a Category i.e Item "Hammer" category: "Tool"

i don't think i want to nest items under their category I.E
Category : {
items: [Item, iTem, Item, Item]
name: "XYZ"
}
because then how will my Listing reference a specific item?

Tirdea Mihai

@Melcus

@ShanonJackson disclaimer : I'm no mongo expert by a long shot. Why not separate Categories and Items ( products?) in 2 different collections ? This example might be relevant - http://learnmongodbthehardway.com/schema/categoryhierarchy/

Christian Amor Kvalheim

@christkv

@ShanonJackson I second @Melcus on the suggestion. Sometimes normalisation is in order.

Jaymin Limbachiya

@jaymin_TFMC_gitlab

Hello

$findRes = $collection->find(
    array('N_NAME'=>' عبدالوهاب علي سليمان')
);

I am trying to run this query to find Arabic records

Jaymin Limbachiya

@jaymin_TFMC_gitlab

record is exist but return array is null

can u please help me to fix lang. issue

Christian Amor Kvalheim

@christkv

you have a white space at the start of your string maybe that is the issue. Mongodb supports utf8 only so you also need to make sure your string is utf8. Not sure what language you are using but you might need to check how you ensure a string is utf8 if the default for the language is not.

puli peter

@peterpuli_twitter

How to fetch the data from mongodb to nodejs and generate the text file or json file

Lakshman

@lakshmankashyap

anybody gave me any link for implement sharding and replica in nodejs

Luis Dasta

@lando786

Can you run commands like .aggregate() on result from a .aggregate()?
such as:
db.collection.aggregate(//logic).aggregate(second aggregation)

najitaleb

@najitaleb

Hi. Is it possible to implement a changestream that only triggers when a document is created, and not deleted?

najitaleb

@najitaleb

never mind i figured it out. I just have to put a conditional for the operationType

Kateryna

@ekaterina1368

Hi!
Does anyone know, what can cause huge schema lock wait time (WT_STAT_SESSION_LOCK_SCHEMA_WAIT)? When that type of lock is used? Thanks!

Arooj

@aroojahmad

Unhandled rejection MongoError: not authorized on admin to execute command { listIndexes: "sessions", cursor: { } }
at Function.MongoError.create (/Users/Arooj/Desktop/projects/ahmadinc/node_modules/mongodb-core/lib/error.js:31:11)
any ideas how to fix this , using atlas mongodb (previously mlab)

Burak Bayrakdar

@buraequete

Why & how would a simple db.col.find() query need a "schema lock"? On a collection without any schema validation etc.

Arooj

@aroojahmad

Issue connecting session to MongoDB:
https://github.com/jdesboeufs/connect-mongo/issues/333#issuecomment-533927541

Evgen Koshmaryk

@koshmaryk

Hello! Can anyone help? Suppose we have replica_set of 3 members. If one member gone down. After come back and finally getting the ‘SECONDARY’ state by this member is it guaranty of full sync with primary?

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