What I've understood, sails binds collection with its Models. Is there a way i can create a collection on runtime. What i want to do is create a different collection for each user. something like (user_12345, unique for every user).
I've tried waterline and sails-mongo, They allow me to query collections for CRUD operation. but I couldn't understand how to create a new collection using sails-mongo or waterline library. Please help.
Waterline doesn't provide a way to create arbitrary collections in Mongo. The ORM's job is to map the logical models in your app to collections (or tables, or whatever) in your database. It's not clear what you're trying to accomplish by giving each user their own collection, but if it's truly necessary you can still achieve it by just making the raw Mongodb driver a dependency in your project:
npm install --save mongodb
and following the documentation for connecting and creating collections. You won't be able to use Waterline to work with those collections, though; you'll have to use native operations for all inserting, querying, etc.
Related
Can I use mongoengine or djongo for ODM and pymongo for interaction with the db?
I've read these two about something related to my question:
Insert data by pymongo using mongoengine ORM in pyramid
Use MongoEngine and PyMongo together
But, I couldn't find what I'm looking for (I guess).
So here's what I'm trying to find:
¿Does this practice affect the performance of my application?
¿How well recommended is it?
So, if it is recommended, and everything is right, ¿Do I need to put an extra layer of security or something?, because, I want to build an API using the serializations for models that django-rest-framework-mongoengine offers, and then do what I have to do in the view of the API endpoint.
It could be djongo or something like it, what I want is just an ODM for serializing, define a structure for the API and so on, use pymongo for queries, cause according to what I've been reading, mongoengine could make slower the interaction with the db
The term "ORM" does not apply to MongoDB since MongoDB is non-relational. The proper term is "ODM" - object-document mapper.
Generally, a MongoDB ODM is built on top of a MongoDB driver. The functionalities of the ODM and the driver are complementary - the driver provides low-level database access and the ODM provides high-level features like schema, associations, callbacks.
If you want to use the high-level features, it makes sense to use an ODM. If you don't need any of those features and just want to perform basic CRUD operations, using a driver directly is more efficient. Some applications use both of these strategies depending on the operation that needs to be performed.
I want to use the collections as DBs!.. make a connection from nodejs where you can use a collection as a normal database.??
The purpose of this is that I'm going to create two totally different apps, with different collections and documents, but there are data that I need to relate between the two apps. And if the two apps are using the same database, it would be much easier for me.
Well.. MongoDB doesnt do that, what can you do is something like give a prefix name to your collections, "projectA_Users , projectB_Users" and to relate data use the $lookup Aggregate operator to get your relationship. I see something like that on FireBase that you can create a collection inside a document and use find, update, remove on it (here)
Is there a way to switch off the ability of mongo to sporadically create dbs and collections as soon as it sees one in a query. I run queries on the mongo console all the time and mistype a db or collection name, causing mongo to just create one. There should be a switch to have mongo only explicitly create dbs and collections. I can't find one on the docs.
To be clear, MongoDB does not auto create collections or databases on queries. For collections, they are auto created when you actually save data to them. You can test this yourself, run a query on a previously unknown collection in a database like this:
use unknowndb
db.unknowncollection.find()
show collections
No collection named "unknowncollection" shows up until you insert or save into it.
Databases are a bit more complex. A simple "use unknowndb" will not auto create the database. However, if after you do that you run something like "show collections" it will create the empty database.
I agree, an option to control this behavior would be great. Happy to vote for it if you open a Jira ticket at mongoDB.
No, implicit creation of collections and DBs is a feature of the console and may not be disabled. You might take a look at the security/authorization/role features of 2.6 and see if anything might help (although there's not something that exactly matches your request as far as I know).
I'd suggest looking through the MongoDB issues/bug/requests database system here to and optionally add the feature request if it doesn't already exist.
For people who are using Mongoose, a new database will get created automatically if your Mongoose Schema contains any form of index. This is because Mongo needs to create a database before it can insert said index.
Is there a way to switch off the ability of mongo to sporadically create dbs and collections as soon as it sees one in a query. I run queries on the mongo console all the time and mistype a db or collection name, causing mongo to just create one. There should be a switch to have mongo only explicitly create dbs and collections. I can't find one on the docs.
To be clear, MongoDB does not auto create collections or databases on queries. For collections, they are auto created when you actually save data to them. You can test this yourself, run a query on a previously unknown collection in a database like this:
use unknowndb
db.unknowncollection.find()
show collections
No collection named "unknowncollection" shows up until you insert or save into it.
Databases are a bit more complex. A simple "use unknowndb" will not auto create the database. However, if after you do that you run something like "show collections" it will create the empty database.
I agree, an option to control this behavior would be great. Happy to vote for it if you open a Jira ticket at mongoDB.
No, implicit creation of collections and DBs is a feature of the console and may not be disabled. You might take a look at the security/authorization/role features of 2.6 and see if anything might help (although there's not something that exactly matches your request as far as I know).
I'd suggest looking through the MongoDB issues/bug/requests database system here to and optionally add the feature request if it doesn't already exist.
For people who are using Mongoose, a new database will get created automatically if your Mongoose Schema contains any form of index. This is because Mongo needs to create a database before it can insert said index.
I am currently evaluating mongodb for a project I have started but I can't find any information on what the equivalent of an SQL view in mongodb would be. What I need, that an SQL view provides, is to lump together data from different tables (collections) into a single collection.
I want nothing more than to clump some documents together and label them as a single document. Here's an example:
I have the following documents:
cc_address
us_address
billing_address
shipping_address
But in my application, I'd like to see all of my addresses and be able to manage them in a single document.
In other cases, I may just want a couple of fields from collections:
I have the following documents:
fb_contact
twitter_contact
google_contact
reddit_contact
each of these documents have fields that align, like firstname lastname and email, but they also have fields that don't align. I'd like to be able to compile them into a single document that only contains the fields that align.
This can be accomplished by Views in SQL correct? Can I accomplish this kind of functionality in MongoDb?
The question is quite old already. However, since mongodb v3.2 you can use $lookup in order to join data of different collections together as long as the collections are unsharded.
Since mongodb v3.4 you can also create read-only views.
There are no "joins" in MongoDB. As said by JonnyHK, you can either enormalize your data or you use embedded documents or you perform multiple queries
However, you could also use Map-Reduce.
or if you're prepared to use the development branch, you could test the new aggregation framework though maybe it's too much? This new framework will be in the soon-to-be-released 2.2, which is production-ready unlike 2.1.x.
Here's the SQL-Mongo chart also, which may be of some help in your learning.
Update: Based on your re-edit, you don't need Map-Reduce or the Aggregation Framework because you're just querying.
You're essentially doing joins, querying multiple documents and merging the results. The place to do this is within your application on the client-side.
MongoDB queries never span more than a single collection as there is no support for joins. So if you have related data you need available in the results of a query you must either add that related data to the collection you're querying (i.e. denormalize your data), or make a separate query for it from another collection.
I am currently evaluating mongodb for a project I have started but I
can't find any information on what the equivalent of an SQL view in
mongodb would be
In addition to this answer, mongodb now has on-demand materialized views. In a nutshell, this feature allows you to use aggregate and $merge (in 4.2) to create/update a quick view collection that you can query from faster. The strategy is used to update the quick view collection whenever the main collection has a record change. This has the side effect unlike SQL of increasing your data storage size. But the benefits can be huge depending on your querying needs.