Develop Reference

how to check if value exists in realtime database firebase

I have created a realtime database on firebase and having no issues adding and removing data in tables etc.
I currently have it setup like this:
So my goal is to check if a given value is inside my database currently.
for example, I would like to check if 'max' is currently a username in my database.
var data = db.ref('loginInfo/');
data.on('value', function(snapshot) {
_this.users = snapshot.val()
});
That is how I get all the values, it is saved into _this.users
(How do i check if a value is inside this object, i am making a login program)
if i console.log the object, this is what I see:
image

If you want to check if a child node exists under loginInfo where the username property has a value of max, you can use the following query for that:
var ref = db.ref('loginInfo/');
var query = ref.orderByChild('username').equalTo('max');
query.once('value', function(snapshot) {
console.log(snapshot.exists());
});
I'd also recommend reading the Firebase documentation on queries, as there are many more options.

Node mssql: return id after SQL insertion

I am working on an integration between Mongodb and SQL Server, inserting and updating registers from MongoDb to SQL Server database with a scheduled process, using the mssql package to achieve this.
Each time a new register is inserted, I want the new row id to be retrieved back, because I need it to perform another insertions of subregisters.
I tried the following, expecting to have some information retrieved in the result of the query. The query actually inserts the row, but result is returned as undefined:
var sql = require('mssql');
var connectionConfig = 'xxxxxxxxxxxx';
var insertionQuery = 'xxxxxxxxxxxx';
sql.connect(connectionConfig).then(pool => {
pool
.request()
.query(insertionQuery);
}).then(result => {
//I expect 'result' to have information of the inserted row, but it comes undefined instead
cosole.log(result);
}).catch(err => {
console.err(err);
});
I think using stored procedures may work around this, but I just want to avoid using a stored procedure for simple inserts.
Does anyone knows how to have the new row id back after insertion?
EDIT
I did include OUTPUT SCOPE_IDENTITY() in my SQL statement - my query now looks like:
INSERT INTO TABLE (columns...)
OUTPUT SCOPE_IDENTITY()
VALUES (values...)
If I run the query in my SQL Server Management Studio, it works just fine and I got my new row id returned, but when running the query through the mssql package's query method, result is returned like this:
[ { '': null } ]

I quote from node-mssql insert returning undefined recordset:
INSERT statement doesn't return a recordset so recordset is
undefined. Please see this section of the docs to learn more
about how to get number of affected rows.
An option to solve this is to add a SELECT statement after your INSERT and ask for SCOPE_IDENTITY() or ##IDENTITY. That will get you the ID of the last inserted objects, i.e.:INSERT INTO table (...) VALUES (...); SELECT SCOPE_IDENTITY() AS id;

If anyone comes having problems with GUID, since you cannot set it as an Identity column, you must do something like:
const result = await pool
.request()
.input('orgName', sql.VarChar, orgName)
.input('tier', sql.Int, tier)
.input('status', sql.Int, status)
.input('createDate', sql.Date, new Date())
.input('statusChangeDate', sql.Date, new Date())
.query(`INSERT INTO app.Organizations (OrgName,
Tier, Status, CreateDate, StatusChangeDate)
OUTPUT inserted.OrgID
VALUES (#orgName, #tier, #status, #createDate, #statusChangeDate);
`)
Where the orgID is the auto generated GUID. Also don't follow my new Date() example as it inserts the date as tomorrow... I need to fix that.

Mongo DB - Why my Users.findOne is Undefined?

I'm working on Meteor, trying to find some values from Mongodb collection.
here is the code:
var sameLogins = Users.findOne({login: 'a'});
console.log(sameLogins);
But it's returning and "undefined".
But record exists in collection:
So, can anybody tell what I'm missing?
Also, in mongo console - everything is working fine:
I was looking in Publish/Subsribe stuff, but i'm using autopublish module yet.
Thank you!

I will leave the answer for this issue for new users having the same problem.
If you're using autopublish package then you should be aware that it's publishing the result of .find() for every collection.
But, Meteor.users.find(), be default, will return only _id and profile fields, so documents in your Meteor.users client collection will have these two fields only.
The most easy workaround for this would be to create your own publication (allUsers, for example) and in it to return those fields you need:
Server:
Meteor.publish('allUsers', () => {
// check for Meteor.userId() is omitted, put it here, if needed
return Meteor.users.find({}, { fields: { ... } });
});
Don't forget to subscribe to it:
Client:
Meteor.subscribe('allUsers');

Update for Meteor:
Right now you are storing a cursor in your variable sameLogins. In order to retrieve the results you want, you must actually execute this query by either calling fetch(). What is returned from findOne without fetch is essentially an object that you could use to iterate over and find mongoDB documents - (called a collection cursor). The cursor is not your result itself.
Calling fetch would like something like:
Users.findOne({login: 'a'}).fetch()

How to prevent RethinkDB from creating test database

When you launch a rethinkdb instance, it will automatically create a database called 'test'. When you run multiple instances and cluster them using rethinkdb proxy this leads to the issue:
Database name conflict: test is the name of more than one database
If you try to delete the databases i.e using
r.dbDrop('test').run(conn, function(result) {
console.log(result) // Will result in error
});
This will produce the following error:
ReqlOpFailedError: Database 'test' is ambiguous; there are multiple databases with that name in r.dbDrop("test")
So how to prevent RethinkDB from creating the 'test' database automatically? Or how to remove a database if you run into name conflict?

If you use rethinkdb create to create a data directory, no test database will be created.
For example, if rethinkdb_data doesn't exist, this will create it with no test database:
rethinkdb create
rethinkdb
This will do the same, but uses -d to specify the location of the data directory:
rethinkdb create -d /var/lib/rethinkdb/data
rethinkdb -d /var/lib/rethinkdb/data

After digging for a while I didn't find any good options to prevent RethinkDB from trying to create the default test database on startup. The problem above only occurs when the cluster nodes use different data directories. Otherwise they will not try to create extra test databases as the other nodes will simply recognise it already exists (created by the first node that launched).
I ended up solving this in my backend software by enumerating all database named test during startup from the db_config table in rethinkdb database.
Example:
// Read from the database 'rethinkdb' that holds information about other databases
r.db("rethinkdb")
// Table db_config contains database id, name information
.table("db_config")
// Filter by name 'test'
.filter({name: "test"})
.run(conn, function(err, cursor) {
// Get results from cursor by id and rename
cursor.each(function(err, result){
r.db("rethinkdb")
.get(result.id)
.update({name: "other_name"})
.run(conn, function(err, result) {
console.log(result.replaced);
});
});
});

Cloud code not working

i am new at parse..trying code..trying to run a trigger required in my project.but not able to track not even i am getting any error.
i am using cloud code i.e triggers...
what i want to do is, after update or save i want to run a trigger which will a column in a class with value of 200.
Parse.initialize('APPLICATION_ID', 'JAVASCRIPT_KEY');
Parse.Cloud.afterSave("match_status", function(request)
{
var query = new Parse.Query('Wallet');
query.set("wallet_coines_number", 200);
query.equalTo("objectId", "FrbLo6v5ux");
query.save();
});
i am using afterSave trigger in which match_status is my trigger name. after that i making a object called query of Wallet class. This object will set column 'wallet_coines_number' with the value 200 where objectId is FrbLo6v5ux. after that i used save function which will execute query.
Please guide me if i am wrong, or following wrong approach.
Thank You !

Have you read the Parse documentation on Cloud Code ?
The first line of your code is only relevant when you are initialising Parse JavaScript SDK in a web page, you do not need to initialise anything in Parse cloud code in the main.js file. Also you cannot use a query to save/update an object. A query is for searching/finding objects, when you want to save or update an object you need to create a Parse.Object and save that.
So you code should become something like:
Parse.Cloud.afterSave("match_status", function(request) {
var wallet = new Parse.Object('Wallet');
wallet.set("wallet_coines_number", 200);
wallet.set("objectId", "FrbLo6v5ux");
wallet.save();
});