How do I share a sqlite database between a Xamarin app and Java Android app

2
votes

As the title says I am wanting to share a Sqlite database between an Android app written in Java and one written in C# using Xamarin. I can successfully share a database between two Java apps (With the help of this question) but when I try the same thing in Xamarin I am getting the following error:

Android.Database.Sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database

I think I have two problems.

  1. I am not correctly setting the Shared UserId. Currently I am placing the following attribute above my main activity.

    [Register("my.user.id")]

    I tried using the android:sharedUserId="my.user.id" in the Manifest file but that was throwing errors and wouldn't deploy to my device.

  2. I don't know how the whole signing of the app works. So maybe my device sees the two apps as coming from a different publisher for each device and is not allowing the two to share context.

EDIT :
Just wanted to add how I signed both applications with the same certificate for future refrence.

The Android cert is noramlly "C:\Users\userName\.android\debug.keystore" and the Xamarin cert is noramlly in "C:\Users\userName\AppData\Local\Xamarin\Mono for Android\debug.keystore". I built the Xamarin app first so I copied the debug.keystore file from the xamarin folder to the android one. (I'm sure it would work the other way around but haven't tested it)

1
c#androidsqlitexamarinxamarin.android

1 Answers

2
votes

Xamarin.Android does not support SharedUserId via an ApplicationAttribute. (I guess no one every filed an issue about it)

Ref: Android.App.ApplicationAttribute

Add your shared user id via the manifest and it will work fine:

Example:

<application android:allowBackup="true" android:sharedUserId="com.sushihangover" android:icon="@mipmap/icon" android:label="@string/app_name"></application>

Note: Make sure that you manually uninstall both apps, add the sharedUserId, rebuild and reinstall both apps.

Note: Make sure that you are using the same signing certificate for both your Java and Xamarin apps.