I am new to android app development I am creating an app which creates a database called couchbase.
If I close my app, data stored in database is lost.
how can I create the database so that data remains even after closing the app.
Also I cannot find the database file. please tell where it is saved
I followed this tutorial:
https://acadgild.com/blog/working-with-couchbase-database-in-android-apps/
Also I cannot find the database file. please tell where it is saved
Which version of Couchbase Lite are you using ?
In 1.4, you can use the getDirectory() method on CBLManager to get the location where the DB is stored
In 2.0, you can look up the Directory property on DatabaseConfiguration
And you may want to check sample Android apps on GitHub (https://github.com/couchbaselabs) on how to get started with Couchbase Lite.
As mentioned by others, without any code describing what you are attempting to do, it's not feasible to determine what may be going on.
Related
This is my first time working on a Xamarin App and I am new to the app development world so I need some help figuring out this process.
Currently I run a php web service that generates some SQL files that I run in DB Browser and I get a database file which I then put into my Assets and Resources Folder. Using each platform's API I copy the database into a writable folder and use that to run my queries.
I followed this really helpful tutorial and it worked perfectly fine.
https://medium.com/#hameedkunkanoor/creating-a-sqlite-databse-and-storing-your-data-in-your-android-and-ios-application-in-xamarin-2ebaa79cdff0 .
After the "initial" setup I store a timestamp in a local table and and the next time the user opens the app I pass that timestamp and retrieve data that is older than that timestamp. The I update that timestamp and continue the process. That data is sent back in JSON format and make the updates to the tables.
My only concern is if a new version were to come out where I add a new table or a new column which is not present in the current version of my Database, how should I take care of those update Web Service calls? Is there a way of monitoring my DB version? I read somewhere where I could just ignore the new data that is not present already, like table or columns, but I'm not really sure how to do that.
I also saw that if I call CreateTable on my current tables I could potentially update them?
Also for future reference each time I develop a new app would I need to regenerate a new database file to store in the assets/resources folder? Is there a more automated process for this? Along with monitoring the version of my database?
Any Help/Tutorials/Suggestions would be greatly appreciated.
You have to remember that CreateTable it's already doing the columns update for you, because internally it calls a method called MigrateTable which you can see here for further clarification: https://github.com/praeclarum/sqlite-net/blob/master/src/SQLite.cs#L562.
However you could have to handle more advanced modification to your database, like adding triggers or something similar.
In that case i suggest you to perform modifications manually.
In Xamarin Forms i've ended up with this:
https://gist.github.com/matpag/b2545cc22c8e22449cd7eaf6b4910396
Could not be the best strategy ever but seems to work for me.
Summarizing :
You have to save the database version in an internal flag of the SQlite database called user_version accessible with PRAGMA keyword.
Every time you get the database connection, you have to perform a check and see if the current database version is the same as the app last database version.
If not you need to perform a database update and set the new current version.
Reference here.
I'd like to receive some advice from all of you.
What is the best way for me to alert users on an update to my app? My app is a very knowledge-based & it works like a dictionary, so there will always be updates to it.
The database I have used is by DB Browser for SQLite, and they are all local database where it is uploaded into the assets folder in Android Studio.
Currently, the limitations are that:
1) it's obviously not real-time because it's stored locally;
2) every update I make to the database structure, I am required to upload the new database into the assets folder again, followed by uninstalling the old app on my phone, then run the app to install in my phone again so that the new database is overwritten.
I have read (How can I regularly update a database of content on an Android app?) & some others, and it seemed like I have to have a server, a cloud-based database & live app in market, to solve the limitations?
Is there really no way for me to overcome the limitations if I want to stick to a local database? At the same time, I kinda wish to avoid setting up a server because I am not intending to make the app live on market, and also this is just a school project I am working on and as such, I have very limited skill sets & knowledge about it and would like to make it on a school-project-based level.
Thanks in advance.
One way to do it is to connect to your local DB through local network instead of assets folder. Therefore, you can update the information by querying the local DB.
As for syncing the information between DB and your application, you should create a trigger or watcher that notify your application when the DB is updated. Therefore, your application can know when to query the DB for the updates. Another way is to just query the database periodically.
Bonus: you could move your database to a cloud-based database. Usually there are several providers that provide free database hosting up to a certain size, which should be enough for your project.
New to Android app building. I built our company website using php/mysql and my boss had an android app built previously with, I assume SQLlite, or something. Anyway, he wants me to change the database that it's currently linked with to our mysql db. For the life of me I cannot find anything even resembling a connection string or a query in the file system? In my attached screenshot where would I find this information? Or is it not held in this tree at all?
I would assume the data/model folders, but I've searched every single file in those folders. I really need some help.
SQLite is a local db. There would be no connection string, its literally accessed as part of your process.
You should NOT directly connect to a remote db. Doing so is completely insecure, as it would be putting the password for your db into the app. You need to run a web service, and hit that to get your data. The web service then connects to the db.
You should also probably figure out what the actual project is. With SQLite, you would work offline, based off a copy of the data stored locally. With a remote db, offline use is impossible. Being told to replace SQLite with a remote db and your level of understanding of that in this question shows that one or both of you don't understand what the scope of that change is, and you should make sure you're on the same page and what the best way to achieve the actual goal of your project is.
In my app I have a SQLite DB want to backup to server but what I want is one to one synchronization for off-line backup (e.g. standalone SQLite file instead of a centralized MySQL server, mainly performance reason and I don't need real time query)
Ideally I don't want to upload the database everytime when I need to sync, prefer only sync the changes?
Are there any existing solution for this? (I can consider using other file DB as currently I mainly use SQLite as Key-Value database)
Thanks.
As you are willing to consider using a different DB, take a look at TouchDB-Android. This syncs a database on an Android device to a CouchDB server. There is a related project SyncPoint, that automates setting up a database for each user.
We are using TouchDb-iOS for our product at the moment are planning work on an Android version using TouchDB-Android soon.
The development community is active. Check out the user group.
I'm developing an Android app as a "proof of concept" for our company. If they like it and think it's worth investing, then we'll move on to bigger things. I'm trying to figure out the best/most practical approach for this.....the basics of the app will connect to our DB and display information regarding a specific customer. For now, let's say we will only pull data from 3-4 tables (but there could be 10+ in the future). If the app doesn't have an internet connection then it should use the local DB. What is the best approach for this? Here's what I was thinking and would like some input/suggestions if possible:
1.) app runs checks internet connection. If exists, check db version (how, through a web service?)..if server db is newer, get latest data. If no internet, use local db.
2.) app parses data and displays it.
If this is correct, then there could be no modifications to the web service that would add fields to a result without changing the app as well. Is there a way for an app to parse fields regardless of how many fields there are?
I've read and walked through the tutorial on google with databases and such (Notepad tutorial) but it seems like the column names are all hard-coded in the parsing class, which I was hoping to avoid.
Sorry if this is confusing but I know I need my app to use a local db to read data, I also know that the app must get data from the server when it can (via onCreate or a refresh button) and copy it locally....Copying it locally is the part I'm having trouble understanding I guess....is there no way of saying "go out and get this result and display it", knowing that those results could mean 5 fields the first time or 1 the next.
Any help/guidance is greatly appreciated!
You probably want to use a SQLLite DB to store your data locally, a ContentProvider to provide CRUD access to the db, and a SyncAdapter to sync with your server when possible. The Sync Adapter also writes to the DB via the ContentProvider. See the SampleSyncAdapter sample in the SDK for an example of how this works. You will be implementing your own ContentProvider, but the sample just uses Android's supplied Contacts ContentProvider.
http://developer.android.com/resources/samples/SampleSyncAdapter/index.html