I have an issue of saving app data internally on device, Well this go like below:
App is service based. We send a request a for particular home project and it will respond with an image of the project and a list of operations. And they want every link to be clickable and on click of that show more links with some text and images. Means lot of data to be handle.
The data which store internally should also get updates. So what could be the better option of saving it. Download files, download more files when update is required or go with SQLite database, which will update the existing db only.
Till now I am finding to create sqlite db as a better option, but still I want to know which could be the better option. I know this would create a memory issue, but this is what client want.
Related
About Single Sources of Truth Google document said:
Using this model, the database serves as the single source of truth, and other parts of the app access it using our UserRepository. Regardless of whether you use a disk cache, we recommend that your repository designate a data source as the single source of truth for the rest of your app
https://developer.android.com/jetpack/guide?gclid=CjwKCAjwo4mIBhBsEiwAKgzXOH1Pq--Ws1PLzUiSP4RmDE6ByKfEi6mdXu5g86btqveIdJvvrgYuxBoCz8wQAvD_BwE&gclsrc=aw.ds#connect-viewmodel-repository
According to the document I save all data when I fected data from remote server and I only get data from room When I need to use in acitivty(In fact I collect flow which is defined in viewmodel).
It seems so good! It avoids the different data sources mix up together! But actually I found some strange question gradually:
In my App, I have a list that the server may change it(Because we have data manager website that admin can update or delete data). So in order to get the newest list data from server, I must clear all data stored in room and fect data again from remote server. This operation seems redundant: "why could I get data directly from remote server", I mean, I only get data from remote source is also a single sources truth. And also it cause a promble: my app will flash a moment because clear data make list empty and fect data from server make list full!
The most important thing is that it seems like the local data is not necessary because I must stay the newest list from remote server.
Some people may say that save data into room can make us app available offlice. I agree that, But in this place, my item of list is represent a image url, and after click the item, the app will jump to a new activity and display a ImageView base on the url we get from the list. If app offlice, the ImageView couldn't load the url also.
I am so confused I couldn't load all image url(use base64-url to avoid load invalid) in a moment also, because the data is so much. And if I say I need a search function in this list and I need load so much unbelievable data into my room, It seems so unreal and event fantasy!
In brief：
Room is a nessary? Couldnt just fect data from remote?
If room is nessary, how to solve problem I met, do my incorrect useage cause the problem?
Hi #psycongroo as I Understood your problem, and I want to share my experience:
You can handle any error with loading URL with placeholder I mean if you got an error with no Internet connection user will see placeholder, but in general libs like Picasso or Glide can cache images when it`s load one time, so the user will see the Image.
The question about why we need to use room instead of fetch data from remote directly. So from your question I don`t understand why you need to drop your local changes even they are completely new, user can have a low internet connection so he will see an empty list instead of previous data with for example progress indicator. And also if the user doesn't have the internet at all you can show some dialog to explain what the problem but old data is still present. If you are using, for example, RecyclerView you can update data with Paging 3 from google, and they update the only necessary items from your list.
P.S. let me know if that help, or you have another question.
So the app is for a Parrot Rescue. It will contain profiles for each of the birds that we currently have for adoption. So a picture of the bird, and then basic info about the bird. It needs to be regularly updated as the birds are adopted out and new ones come in. What route should I go? My main concern is that I want it to be relatively easy to update so that some of the less technically inclined could use it, as I won't always be available to help them.
Instead of loading a new version of the application every time, you should implement a database on a parrot information server. Then the application (the client) will ask the server to receive parrot information.
Just implement a mySQL database and a PHP page that returns the information in JSON format. Then through the application you will make a request to the server using the volley library or okHTTP and enter the information into a list.
As there are also pictures, use the glide library to download the images.
Also remember to upload small images to the server.
This way the app is always up to date
The easiest way is to update the app on the play store with the newest db, and let auto-update update the app with the new db.
Next easiest is to have a nightly (or whatever frequency) service download a new db and replace the old one from your servers
If you want it to be as easy as possible to update for everyone I would recommend a little app that has two main activities. One for displaying the entries of the database (and maybe also giving the ability to delete the entry) and another with a template to fill with all information and the image.
Then like Raffaele D'Arco explained use a little server. You could also delay the updates to be in a 5 minute routine or the like so that you put as little stress as possible on the server.
There are multiple good ways to update the interface without updating the app constantly.
Use a database which the app will download after a fixed amount of time which will be located on the server.
Secondly, if you have a website you can convert the web pages to XML or JSON or something like that and can update the app UI as per the data downloaded from the website.
I would recommend the second option as it is quite easy than the first one...
Context
I have a news activity which contains a ListView . Each item in the list contains some text and one image. Now every time the user opens the activity, the application makes a request to the server for getting data. Unfortunately if the user doesn't have an active internet connection, I simply put a Toast saying "Please check your internet connection"
Requirements
I would like to show news article from the last session if the user doesn't have an active internet connection. I define session as the time when user launches the activity and exits it by pressing back button.
Libraries used
I am using Retrofit Library for making Http Requests and Picasso for loading images.
What I have tried so far
While exploring Retrofit, I found out that retrofit by default caches the response for some time. So without any internet connection also I am able to get the data. In Picasso also, I found that we can save the image to any location on the device.
How to go for its Implementation ?
Since it will be a big change in my application, I wanted to know what is the best way to enable offline reading using the above two libraries? How do other applications manage to do so? Also if I can get some references or some blogs regarding this implementation, then it would be great.
Use the internal storage of the application.
Parse the image to a byteArray and the text to a single String so you can easily convert this also to a byteArray.
Name the files so you can easily retrieve them and link them back together.
You can storage the last updated data on local, with SharedPreferences or json file.
Instead of show toast, you can load the last updated data from local.
Picasso is a good choice for images, it saves images locally and reuse it automatically later.
For your items, I suggest to use a small local DataBase : in Android, we use SQLiteDataBase. here is a small tutorial : http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/
So, I suggest you this pattern
user opens activity
system retrieves data from database
in parallel, system starts to download the new items.
When new items have been downloaded, you should notice user like 9gag or Facebook apps do.
I have an external database on Azure that holds large amounts of information. My app needs to be able to synchronize a selection of this data and store it locally on the app's database. I currently use web services to make calls to the database. When the app starts for the first time, it will have a large amount of data that would need to be downloaded. What's the most efficient way of downloading a large number of rows from the external database? I was thinking an XML file might be the best way, but I'm not sure. There could be thousands of rows that need downloading so I'm not sure which method would be the most appropriate.
There isn't 300 ways to download data, so you'll basically have to call your API and get the data. For obvious performance reasons, I would avoid XML and prefere JSON instead. So once you've got your JSON file, you parse it and put it in the locale database. I also would suggest you to use service as it won't be interupt, and don't forget to warn the user that you gonna download massive data ;)
If you wan't to minimize the amount of data downloaded, you can store a JSON file for example in the assets that will contains all the things "static" that won't change online.
I would offload the work to some sort of service. Services have the benefit of running in the background without interacting with the application. You would still need to create another thread to do the work. When the download is finished, it will simply destroy itself.
Data should be downloaded anyway whatever method you use, maybe you may prepare the initial data as XML file, download it the first time and store the data in the database showing a progress bar to the user
I have made an application which is about pets, at first I had kept the database local to the phone, however as new features arrive I want to make it a network based application with remote database. However I have around 500 downloads on the play store and I dont want my previous users to lose data. I came up with an idea of rolling out an update in which I copy all the databases to the SD card and then mail them back to me and update them in the remote database. I wonder if there is a better way to go around this. Help will be highly appreciated.
A better way would be to write a webservice to which you can send the database row by row. The webservice will then update your Server database(s).
This not only prevents duplication of your database between internal and external memory, but it also allows automation and more flexibility in the update process. You can also pause the transfer, and pick up from whichever row was last sent easily.