I'm working on an Angular2 project (Resource Management) which requires data from the database (mongoDB) in real time. The basic function of the application is to drag a resource from bench and drop it to a project. After which a button is clicked which saves these values to the database. The problem is once the database is hit with the values, the same is not showing up unless the page is refreshed. Is there a way where we can pull data from the database without manually refreshing the entire page or pulling the data from DB at regular intervals so that the services have the latest data. I'm attaching my code here: Resource Management (drag n drop)
Thank you!!
If you want to get the data periodically.You can use timer.
ngOnInit() {
this.timer = Observable.timer(2000,5000);
// subscribing to a observable returns a subscription object
this.sub = this.timer.subscribe(t => this.geData(t));
}
geData(t) {
console.log(t)
}
You Could use socket.io for real time update with angular2 and mongodb
Related
I'm developing a Xamarin.Forms app which uses an Azure app service with SQL database linked through EasyTables. I've run the samples and successfully tested querying tables etc on the server and enabled offline sync so as a localdb is created.
I've created the store, defined the table & sync'd it, however I want to be able to query it somehow with a where clause - is that possible? Can I add a where clause to the client.GetSyncTable line?
var store = new MobileServiceSQLiteStore("localstore.db");
store.DefineTable<Journey_Stages>();
client.SyncContext.InitializeAsync(store);
tbl_Stages = client.GetSyncTable<Journey_Stages>();
Some of the tables I'm pulling down will grow over time & are linked to individual user profiles, so I only want data which belongs to that user and I don't want to be bringing down masses of data each time, preferably let the server handle that and only bring down what I need on a user by user basis.
Thanks,
Steve
You should add this filtering logic on the server side, so that each user's data isn't exposed to all your other users. See for example this sample if you are using the Node.js backend -- line 17 adds a WHERE clause for the table read query. If you have the .Net backend, similar logic would go in your table controller.
// Configure specific code when the client does a request
// READ - only return records belonging to the authenticated user
table.read(function (context) {
context.query.where({ userId: context.user.id });
return context.execute();
});
I am new to Azure App Service.
I've created a view in Azure database to get data across several tables. Now I want to use the data from this view in my Cordova App using the Azure Mobile Service (MobileService.GetTable...). I found several articles in the web that describe how to do that in Classic Azure Portal. But I need a solution for the NEW Azure App Service with Node.js Backend.
What is the syntax to return data from a view as an Azure table?
var table = module.exports = require('azure-mobile-apps').table();
table.read(function (context) {
// *** Need code to return data from sql view ***
//return context.execute();
});
And it would be great to use a parameter to filter data in the view before returning.
Thanks,
Uwe
You are pretty much right there. You need to just create a table controller to access the view. Ensure you have the system columns defined (version, updatedAt, createdAt, deleted and id). Also, ensure the right thing happens when you update the view (e.g. with an INSERT, UPDATE, DELETE) as that will tell you what needs to be done with the controller (for example, if you can't insert/update/delete, then make it read-only).
Reference blog post for you: https://shellmonger.com/2016/04/15/30-days-of-zumo-v2-azure-mobile-apps-day-8-table-controller-basics/
Things can be so easy sometimes ;-)
All I need to do is to write the following lines to my table controller:
var table = require('azure-mobile-apps').table();
table.databaseTableName = 'ViewName';
module.exports = table;
Thanks for your help!
Had a similar issue but fixed it now, am using a .Net backend thou.
1. Log into azure portal and select the database you want to create the view in Then select the query Editor in the left pane.
2. Use the sql to create the query.
3.Create a table in the asp.net backend that matches your fields in your view.
4.Go to your asp.net backend and create a custom Api and write the following codes:
public class HelloCustomController : ApiController
{
MobileServiceContext context;
public HelloCustomController()
{
context = new MobileServiceContext();
}
[HttpGet]
public async Task<List<vwUser>> Get()
{
try
{
var users = context.Database.SqlQuery<vwUser>("Select * from
dbo.vwUser);
return await users.ToListAsync();
}
catch(Exception ex)
{
return new List<vwUser>()
{
new vwUser
{
UserName=ex.Message
}
};
}
}
4.You edit my codes to select from your view.
5. Create a similar class in your mobile app that matches what u created in your backend.
5. You can then access your view by calling it in your mobile app with the following codes:
var users= await client.InvokeApiAsync<vwUser>("HelloCustom",HttpMethod.Get,null);
Thanks Guys. This is my fisrt answer to this beautiful community that carried me from day 1 of programming till now that am a bit conversant.
I have a question about subscription/publication in meteor.
When you subscribe to a publication in meteor, is the client database updated or only a copy at one moment of the server database?
In fact, will Meteor update the local database after a subscription, or will it just be an image of the server's database at a T moment where T is the moment of subscription ? And can I get the last data when I call Collection.find() on client side ?
The quick answer is that as long as your subscription is still active, Meteor will keep the client in sync with the server per the rule you defined in the publish() method. It is not a copy at time T, it starts at time T and is amended as the server collection changes.
For example:
/server/publish/people.js:
Meteor.publish('people', function() {
return People.find();
}
/client/app.js:
Meteor.subscribe('people');
The publish()'s 'People.find()' will be monitored and any changes to the query will be replicated on the client. If you have reactive queries (People.find() in a template helper for example) on the client, those will be re-executed automatically and the template updated (see Tracker).
Good reference for you: https://www.discovermeteor.com/blog/understanding-meteor-publications-and-subscriptions/
After reading the documentation I was expecting that this field is automatically set by Azure Mobile Services. Apparently it isn't.
Should I configure something extra?
Other options that I see (to do for each table):
* add an axtra line to the node js update(item, user, request) function:
item.__updatedAt = new Date();
* create an update trigger in the database
Anybody experience with this?
Thx!
The __updatedAt column is updated by a trigger created in the underlying SQL Server database, so it should be updated any time a row is updated. Note that this requires a database operation to occur for it to be updated.
I have a Azure Cloud Service based HTTP API which is currently serving its data out of an Azure SQL database. We also have a in role cache at the WebRole side.
Generally this model is working fine for us but sometimes what happening is that we get a large number of requests for the same resource within a short period of time span and if that resource is not there in the cache, all the requests went directly to our DB which is a problem for us as many time DB is not able to take that much load.
By looking at the nature of the problem, it seems like it should be a pretty common problem which most of the people build API would face. I was thinking if somehow, I can send only 1st request to DB and hold all the remaining till the time when 1st one completes, to control the load going to DB but I did get any good of doing it. Is there any standard/recommended way of doing it in Azure/IIS?
The way we're handling this kind of scenario is by putting calls to the DB in a lock statement. That way only one caller will hit the DB. Here's pseudo code that you can try:
var cachedItem = ReadFromCache();
if (cachedItem != null)
{
return cachedItem;
}
lock(object)
{
cachedItem = ReadFromCache();
if (cachedItem != null)
{
return cachedItem;
}
var itemsFromDB = ReadFromDB();
putItemsInCache(itemsFromDB);
reurn itemsFromDB;
}