can you please help me,
I am trying to copy all collections in a particular database into create new database and move that collection into it.But the following code does not work. and my colleciton name in the db contains two part ' mg2.data' ,'mg32.data' i want to create new database mg2 and copy collection name as data.
collection name mg2.data suppose to be in mg2 database and collection name data.
db.getCollectionNames().forEach(function( a ){
if(a!='system.indexes' ) {
var sp = a.split('.');
var dbName = sp[0];
var col = sp[1];
//print(dbName)
db[a].copyTo(db.getSiblingDB(dbName).getcCollection(col));
}
});
Here is my situation details.
I am having Db name Master and it contains about 60-70 collections its names like(mg1.data,mg2.data,mg3.data)
and i want it to be like
db name mg1 and collection name data
db name mg2 and collection name data and so on..
i am facing the problem that when in the first design write operation locks entire database(Master). i cannot go for sharding and all now.
I got this approach working for me.I dont know is this best aproach
db.getCollectionNames().forEach(function( a ){
if(a!='system.indexes' ) {
var sp = a.split('.');
var dbName = sp[0];
var col = sp[1];
print(dbName+'\n');
//db[a].copyTo(db.getSiblingDB(dbName).getcCollection(col));
db[a].find().forEach(function(d){ db.getSiblingDB(dbName)[col].insert(d); });
}
});
Related
I am new to Parse Server.
I am having an existing collection "users" in "employee" db in Mongodb.
I need to get the users data using Parse Server.
Below is the code:
var query = new Parse.Query(users);
query.find().then((data) => {
return data;
}).catch((error) => {
return error;
});
But I am getting the error "users" is not defined.
Need some valuable help.
if your Class really is called users (which is different to the built-in Parse Server Class called User), then use :
var query = new Parse.Query('users'); //note the quotation around 'users'
If you are in fact trying to query the built-in User class, use :
var query = new Parse.Query(Parse.User);
or
var query = new Parse.Query('_User');
I am new to the NoSQL world and since Ionic 2 by default supports simple key-value DB, I was to some help here.
My app has a very large form. How do I go about saving new records? How do I retrieve those particular records?
Currently, to save a new record, I am doing something like this:
save(data){
let newData = JSON.stringify(data);
this.storage.set('reports', newData);
}
The problem with this is it overwrites the record instead of inserting a new record.
I am retrieving records like this:
getData() {
return this.storage.get('reports');
}
How do I go about fetching a particular record using certain values in the stored JSON?
Thanks.
What you would have to do is make reports as an array and set it to the storage.
everytime you need to insert a new record, do a
function(newData){
var some_variable = storage.get('reports'); //get Existing Table
some_variable.push(newData); //Inserts the new record to array
storage.set('reports', some_variable); //Saves report with updated data
}
For getting a particular report alone, I hope you have some id or a unique attribute y which you can distinguish a report. Assuming you have the report json as below :
var report {id : "UniqueID", name : "A sample report json"}
Then to get the report,
function(reportId){
var reports = this.storage.get('reports');//fetches your reports Array
var wantedReport = {};//Variable to store the wanted report
reports.forEach(function(r){ //Looping the array.You can use a forloop as well
if(r.id === reportId){ //filtering for the wanted reportId
wantedReport = r; // storing the report to variable
}
})
return wantedReport; //Returning the report to the caller.
}
Alternatively, If you are used to Sql and want a Sql-like way of storing these data then you can install the Sqlite cordova plugin and store your data in a Sqlite DB.
I am getting db is not defined when trying to use mongodb's distinct in meteor.
Template.displayinbox.helpers({
inboxlistings: function() {
itemscount = db.Messages.distinct( "fromUsername" ).count;
return db.Messages.distinct( "fromUsername" );
}
});
I want to be able to return only distinct documents in my collection from the username field and count all those documents that is posted by the fromUsername. How would I go about doing this in Meteor?
When you're querying anything in the Meteor code itself, you don't need to write db first. You have to use the variable name that used to instantiate the Mongo Object. Let's say you defined your Mongo db like this.
example = new Mongo.Collection('Messages');
then within your helper you just use the typical query using this object.
Template.displayinbox.helpers({
inboxlistings: function() {
var items = example.find();
return _uniq(items,function(i){return i.fromUserName;});
}
});
I am creating an app for employees using Meteor and MongoDB. This app will be used by multiple organizations. So I will make a separate DB for each organization. I am facing an issue in Meteor about how to keep database name and collection name as variable. Database name will be decided on login. Then I will keep DB name in Session.
Collection name can also be a variable.
For example:
var dbName = Session.get("dbName"); //for eg dbName="redex"
var collectionName = Session.get("collectionName"); // for ex collectionName="employees"
Employees = new Mongo.Collection(collectionName);
How to manage the variables in this case?
You will have to create a server method that creates a given database according to dbName and collectionName parameters:
'newDatabase': function (dbName, collectionName) {
var d = new MongoInternals.RemoteCollectionDriver(process.env.MONGO_URL.replace("originDB", dbName));
Employees = new Mongo.Collection(collectionName, { _driver: d });
}
You will also have to declare that new collection on your client side:
Meteor.call('newDatabase', Session.get("dbName"), Session.get("collectionName"), function (err, res) {
if (!err)
Employees = new Mongo.Collection(Session.get("collectionName"));
});
I need to iterate through all of the collections in my MongoDB database and get the time when each of the collections was created (I understand that I could get the timestamp of each object in the collection, but I would rather not go that route if a simpler/faster method exists).
This should give you an idea of what I'm trying to do:
MongoDatabase _database;
// code elided
var result = _database.GetAllCollectionNames().Select(collectionName =>
{
_database.GetCollection( collectionName ) //.{GetCreatedDate())
});
As far as I know, MongoDB doesn't keep track of collection creation dates. However, it's really easy to do this yourself. Add a simple method, something like this, and use it whenever you create a new collection:
public static void CreateCollectionWithMetadata(string collectionName)
{
var result = _db.CreateCollection(collectionName);
if (result.Ok)
{
var collectionMetadata = _db.GetCollection("collectionMetadata");
collectionMetadata.Insert(new { Id = collectionName, Created = DateTime.Now });
}
}
Then whenever you need the information just query the collectionMetadata collection. Or, if you want to use an extension method like in your example, do something like this:
public static DateTime GetCreatedDate(this MongoCollection collection)
{
var collectionMetadata = _db.GetCollection("collectionMetadata");
var metadata = collectionMetadata.FindOneById(collection.Name);
var created = metadata["Created"].AsDateTime;
return created;
}
The "creation date" is not part of the collection's metadata. A collection does not "know" when it was created. Some indexes have an ObjectId() which implies a timestamp, but this is not consistent and not reliable.
Therefore, I don't believe this can be done.
Like Mr. Gates VP say, there is no way using the metadata... but you can get the oldest document in the collection and get it from the _id.
Moreover, you can insert an "empty" document in the collection for that purpose without recurring to maintain another collection.
And it's very easy get the oldest document:
old = db.collection.find({}, {_id}).sort({_id: 1}).limit(1)
dat = old._id.getTimestamp()
By default, all collection has an index over _id field, making the find efficient.
(I using MongoDb 3.6)
Seems like it's some necroposting but anyway: I tried to find an answer and got it:
Checked it in Mongo shell, don't know how to use in C#:
// db.payload_metadata.find().limit(1)
ObjectId("60379be2bec7a3c17e6b662b").getTimestamp()
ISODate("2021-02-25T12:45:22Z")