I went thru the docs but couldn't find how can I perform specific operations when app is being installed or when app is being updated.
What I want to do is, create table when app is being installed and if in future, db schema changes, I want to perform those operations when app is being updated.
According to me .. the best place to do these changes are in the code. so whenever the application starts up first time after getting updated.. you do all the db schema changes.
This makes sure that your application is fully updated before you touch any database and secondly u do not have to write any special logic separately while installing / updating the application.
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I'd like to know if such a method exits, so when the user installs an app actualization the database gets properly actualized.
I've found a way that although it can't always work, I think in practice it will never fail, which is the following:
Check if database version of installed app is higher than the version in a hidden file in the previous app, if so, actualize the database.
Write that file with the database version of installed app.
This way, only if the user were to manually remove the file and not the database would cause my solution to fail in its purpose.
Even then it would be better if there was something that works like onUpgrade() from SQLite in Realm.
Is what I'm mentioning possible?
I am developing UWP application using vs studio 2017 version 15.9.6.
I want to use Windows local SQLite database. I want to run an SQL script named mySql.txt when the user first time install the application. I dont want to run it every time when the user run the app as it contain insert statement, which will cause duplicate rows insertion. So I want to run that script only once, preferably in the installation time.
How can I do that? I am very new to UWP and .NET. Please guide me step-by-step if possible.
You can make sure the initialization/seeding is done only once for the app. For that you may utilize ApplicationDate.Current.LocalSettings.
These allow you to write simple data for your application which are bound to your app. Once the user uninstalls the app, these data will be removed as well. This fits your scenario exactly.
Suppose your database initialization code is in the method InitializeDb(). You could use the following to make sure the initialization is done only once:
if (!ApplicationData.Current.LocalSettings.Values.ContainsKey("DbInitialized"))
{
InitializeDb();
ApplicationData.Current.LocalSettings.Values["DbInitialized"] = true;
}
This code first checks if we have initialized the db previously and if not, performs the initialization and stores a flag into app settings to make sure the next time the initialization is skipped.
You can run this code during app initialization, for example in OnLaunched method, or on when the database service is first required.
This is of course the simplest implementation, so you can (and should) add some exception handling, so that if the initialization fails, it can be retried and so on. Also you may want to handle app updates and DB updates - in which case you can use ApplicationData.Current.Version which allows you to track the version of application data and can be used to keep track of DB version as well so you can perform appropriate migrations between versions.
Finally, for even better user convenience, there is also a way to perform the app update steps during updates. See this article for more info.
I'm getting stock quotes which happen a few times a second. I'm using meteor to display those quotes. I don't think meteor can keep up with the database. What's the best way to keep meteor speedy?
Should I set my query to be non-reactive then somehow manually call when meteor should re-render the templates?
If you are updating your db directly (outside of meteor), than meteor will take 10 seconds to reload and recompute the data changes from the database.
If you are updating your db through a DDP connection, than those changes should reflect to your meteor UI almost instantaneously, certainly keeping up with a few updates per second.
Apart from this, your publish function should not expose all fields of a document in bulk. Instead, you should publish just what is necessary to populate your UI.
I understand that meteor automatically updates the view based on the underlying model, ie if there is a model change, then all the clients' views will be updated as well.
What happens if a 3rd party app updates the database directly. Will meteor pick up that model change and display it to the view, or is it only model changes done through the meteor stack that will be updated?
You mean if you have some other app updating the same MongoDB? Meteor will notice and show this change to the user!
If I for example update my MongoDB directly from the MongoHQ's console it's reflected in my app instantly.
Meteor polls MongoDB each ~10 seconds or so. You need to use ddp-client to update MongoDB through Meteor for your changes to affect the model immediately:
Using node ddp-client to insert into a meteor collection from Node
I try to build a database on Icenium with SQLite and the db does not persist - why? I think the structure of the database is not built on a physical level. Someone you ever had this problem?
I was able to use SQLite with Icenium on my project successfully. As I see, there is also an example that you can look up:
https://github.com/Icenium/sample-sqlite.git
You might also want to take a look at this post: Creating a Database from a SQL Dump, for using prepopulated SQLite database.
From my experience with Telerik AppBuilder (formerly called Icenium), each time you Run the project in a simulator, the simulator starts from scratch and it keeps no record of what happened in previous runs.
The solution I would use to 'persist' the database on a session basis and test your code is as below.
You must keep the simulator open (so don't close it) to keep database intact
and just press Reload button in simulator window to see how an existing database
would run on a real device every time the app is re-started on a real device,
because within a single Run of the simulator it remembers everything.
Even if you want to make changes to your code or html, leave the simulator open and make your code changes (and Save), and then click on Refresh button in simulator window to bring in your recent code changes without losing the database and its data. If you follow this approach you can easily test how a database would behave on real device where a database is naturally persisted.
So think, in terms of 'simulator session' when developing hybrid apps using Telerik AppBuilder.