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Auto generate sub database firestore

I have a firestore collection with a bunch of documents, each with plenty subfields. On a web page I need a list of a specific subfields from each document.
Currently I load the the entire database when you load the page and then loop through and get the wanted values. This uses way to many reads to get very little data.
Is there a way to solve this e.g. a autogenerated a collection that contains field from other collection in an array or something.
Many thanks in advance

Auto-creating such a subcollection with just the fields you need is a great way to reduce the bandwidth needed to load the data.
There is nothing built into Firestore to create those derived documents, but it's fairly easy to build something using Cloud Functions. Create a function that responds to a Firestore onWrite trigger, and write the subset of the data to its destination there. It's common to have a separate Cloud Function for each such use-case, and I regularly see projects with 100+ such functions.
I expect we'll also start seeing Firebase Extensions for this type of thing, but right now no-one seems to have built one.

Recommended way to populate a fresh MongoDB instance with data?

I have a local container created with Docker with MongoDB & an express node server
What is the recommended way to populate it with new data?
1) Use the cli
2) Using Mongoose
3) Use a GUI such as Compass
Thanks!

I don't know if there's a 'correct' way to do this, but I've run a couple of 'seeds' files for my projects:
https://github.com/rmgreenstreet/surfShop/blob/master/seeds.js
https://github.com/rmgreenstreet/yelpcamp/blob/master/seeds.js
https://github.com/rmgreenstreet/custom-forms/blob/master/seeds.js
I almost wish there was some kind of niche field/need/position for being able to generate fake data!
The point is that you'll need to set and understand the structure of your data and essentially go through a bunch of nested loops for any connected/dependent data types.
Now if you're working with a SQL database, I'm totally clueless. That's next on my "things to learn" once I feel more comfortable with Javascript/NoSQL.

This would possibly depend on the usecase here,
Answer would be:
MONGOOSE : If you are planning to deploy an application using express. As mongoose goes hand in hand with express. (https://medium.com/#SigniorGratiano/mongoose-and-express-68994fcfdeff) As in many stacks like MEAN, MERN.
GUI like Compass: When you have to visualise the data or do ONE TIME OPERATIONS.

How to use one relational(postGreSql) and one non-relational(MongoDb) database in single node.js application

I have to work on one Node Js project where I have to use two database in single application, One database is MongoDb and the other one is postgreSql. Till now I have only used only one dababase in one project. I just want to know that "Is it possible to use two different database as mentioned above in one Node Js project". If yes can you please provide me essential configs and plugin required to setup the project ?

yeah... NoSQL & another RDBMS together...because
NoSQL: fast and simple, but has little to none structure to enforce constraints on data.
RDBMS: satisfies all ACID properties, keeping your data safe and clean. But performance goes down rapidly as traffic and data set size grow.
for doing so ..
you can use an ODM (Object Document Mapper) like mongoose to deal with mongoDB
& an ORM (Object Relational Mapper) like sequalize to deal with mysql , postgre
As provided in the docs.. you got to install both
npm i -s mongoose sequelize

How can I switch from orchestrate.io db to mongodb

I recently followed a tutorial to create a node.js server connecting to orchestrate.io database. The problem is I now want to point the server at a mongodb hosted on mongolab - currently I am declaring a variable:
var db = require('orchestrate')(APIKEY);
which allows me to retrieve data using something like:
db.get('collection', key)
.then(function(result){
console.log(result.body);
});
My question is - Is there any way I can switch the value of 'db' to point at a mongolab database without changing the structure of the get request?

I work at Orchestrate and we do not believe in data lock-in. I hope you'll reconsider using our service, but here's some advice if you choose to leave...
It sounds like your code is fairly minimal, so you may be best off recreating your Node server with another tutorial specific to Mongo.
That said, if you are using simple key-value storage, it should be as easy as rewriting the db.get Orchestrate lines to be db.find functions from MongoDB. If you've loaded a lot of data you could export it from Orchestrate, then import into Mongo (either manually, or using another tool).
If you're using some advanced, built-in Orchestrate features, such as full-text search, relation graphing, time-series data, and geographic look-ups, it may take some more effort (and MongoDB experience) to switch. If you'd like these features in a highly scalable database-as-a-service that you don't have to maintain, you know where to find us.

Meteor mongo insert unique document

I have a simple Tags Collection in Meteor. Currently in order to ensure that a user cannot create a duplicate Tag document I do this:
var existingTag = Tags.findOne({name: "userInput"})
If existingTag is undefined then I can go ahead and do the insert.
Is there a better/correct way of doing this utilizing meteor mongodb syntax? Cant seem to find any documentation on this.
Thanks.

A good solution is to create Mongo index at the unique field. That way you'll have the uniqueness validation at Mongo level, as well as performance increase for searches on that field.
Meteor currently doesn't support index creation directly, so you need to manually log in to your database and add your index from there. The command for this is:
db.tags.ensureIndex({name: 1}, {unique: true})
Here and here you can find more information.