I'm new to Flutter. I used nodejs and MongoDB as Backend API. How do I access DataModel with ObjectId references in Nested Database in Flutter?
You can simply use populate function with find method in mongodb: Ref
Let's assume that there is userDeatils model which is referenced withing user model like this :
var user = new Schema({
name:String,
userdetails:{
type:mongoose.types.ObjectId,
ref:'userDetails'
}
});
Then You can Find data using Query like :
db.user.find({name:"Ram"}).populate('userdetails')
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i am trying to create group chat system using mongoDB but in mongoose object type is supported how can i create model like this(inserting image below)? and also query this data? i've tried to create schema but didnt work
sample of model (dummy)
const chatSchema = new mongoose.Schema({ users: Array, texts:[{ user: String, text: String, time: Date, }] });
Try this schema. Users who will be in group chat will added in users field. The text will have author(user), text(text) and date(time).
I am new to MongoDB & working on a MEAN application.
In the mongo database(I am using mongoose), the collections are adding dynamically from third party API like schoolList1,schoolList2,schoolList3,schoolList4,....
I am facing problem to find a solution to get data from collections, Like If a user sends the argument from FrontEnd to find data from schoolList3.
The find function should apply on that collection only & return the data.
I am unable to solve it that how should I get data without passing schema and did not get any other way.
Set collection name option for your schema from user's input:
var collectionName = 'schoolList3'; // set value from the input
var dataSchema = new Schema({/** your schema here **/}, { collection: collectionName });
I am trying to convert a string to ObjectId using
var body={};
var objId="57b40595866fdab90268321e";
body.id=mongoose.Types.ObjectId(objId);
myModel.collection.insert(body,function(err,data){
//causing err;
});
the above code is working fine when mongoose 4.4.16 is used, but if i update my mongoose to latest version(4.6.0) then problem occurs.
Err
object [
{
"_bsontype":"ObjectID",
"id:{"0":87,"1":180,"2":5,"3":235,"4":134,"5":111,"6":218,"7":185,"8":2,"9":104,"10":50,"11":111}
}
]
is not a valid ObjectId
The right way to insert new document is-
var newDocument = new myModel({
_id: mongoose.Types.ObjectId("57b40595866fdab90268321e")
});
newDocument.save();
In you case-
It stops working because the differences between versions of mongoose and mongo native drivers.
although, you are able to perform this by the example above, or, if you still want to use insert, you can use the myModel.insertMany (by passing object instead of array)
look here
http://mongoosejs.com/docs/api.html#model_Model.insertMany
I don't have the time to spike it, but if I remember correctly id is a simple string and _id is the ObjectId, i.e. either
body.id="57b40595866fdab90268321e"
or
body._id=mongoose.Types.ObjectId("57b40595866fdab90268321e");
That said, does it have to be that specific id? If not, you can use new myModel() and an id will be automatically created.
I'm trying to build some sort of a social media app using node.js and mongoDB.
I have a mongoose schema for 'User', and when i render some user page on the app, it needs to also show all of his posts/images/list of friends and etc...
right now i have a mongoose schema for 'UserPost' and also for 'Image', and when i save an image for example, it has a field which keeps the username of the user who uploaded it, so when i render the user page it finds all of his images.
It is the first time i'm dealing with db's so i heard that i might have to use a reference data instead of embedded data.
can someone explain to how should i organize the data model for my app?
It's very handful to use mongoose population for handling db references
Define your schemas like these:
var mongoose = require('mongoose')
, Schema = mongoose.Schema
var userSchema = Schema({
name : String,
posts : [{ type: Schema.Types.ObjectId, ref: 'Post' }]
});
var postSchema = Schema({
title : String,
images : [{ url: String, filename: String }]
});
var User = mongoose.model('User', userSchema);
var Post = mongoose.model('Post', postSchema);
According to mongoose population docs, you can get all your data:
User.findOne().populate('posts').exec(function(error, user) {
console.log(user.posts) // there are populated posts objects inside array
})
Not sure, is it a good idea to use separated collection for image uploads, it's simpier to embed it inside Post (or User), but you may always add { type: Schema.Types.ObjectId, ref: 'Image' } for images
MongoDB is a NoSql DBMS. It means, you schould not create references between data fields, because the performance coming from NoSql will be killed: https://en.wikipedia.org/wiki/NoSQL
But, if you are really thinking you need references, checkout this: http://docs.mongodb.org/master/reference/database-references/
You can reference to a data document in the mongoDB by the _id ("Page"=>"createdBy" = "User"=>"_id" for example).
It depends of what kind of data you want to embed. MongoDB has object size limits according to the storage engine you use. Thus you should predict or estimate the the size of the object you want to embed.
See more about limits here: http://docs.mongodb.org/master/reference/limits/
See more about references here: http://docs.mongodb.org/master/reference/database-references/
I am working on a API.I am using mongo DB and mongoose as ORM tool with express. I want to use customer object id for my schema.
I want to implement CURD operation on the schema with customer id. The custom id can be anything for ex: 'someid' or a Number like 1.
The users can query the API using those Id's
I am using Model.create() method to insert and update() method to update and remove() method to delete and findById to find by id
The Schema is defined as
var mySchema = new Schema({
name : {type: String},
email: {type : String}
});
EDIT:
If the ID is not present then generate an auto id