How to use Iridium as a shared cross-platform database solution in Xamarin

[nologinatgit]

I have the following architecture:

• Xamarin.Android project
• Xamarin.iOS project
• .Net Standard 2.0 project (for shared code)

I intend to use Iridium as the database provider in the shared project. I added the Iridium NuGet package to the .Net Standard project and the Xamarin.Android project, and they compiled normally.

After reading the documentation, I added the Iridium.Db.SQLite package to both projects, and tried to create the context with the following code in the shared .Net Standard project:

 public class MyIridiumContext : SqliteContext
  {
    public MyIridiumContext () : base(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "myIridium.db"))
    {
    }

    public IDataSet<Family> Family { get; set; }
  }

Now, when I try to compile, I get the following error in the Xamarin Android project:

Exception while loading assemblies: System.IO.FileNotFoundException: Could not load assembly 'Iridium.DB.Sqlite.Win32, Version=2.2.0.0, Culture=neutral, PublicKeyToken='. Perhaps it doesn't exist in the Mono for Android profile? File name: 'Iridium.DB.Sqlite.Win32.dll' at Java.Interop.Tools.Cecil.DirectoryAssemblyResolver.Resolve(AssemblyNameReference reference, ReaderParameters parameters) at Xamarin.Android.Tasks.ResolveAssemblies.AddAssemblyReferences(DirectoryAssemblyResolver resolver, ICollection`1 assemblies, AssemblyDefinition assembly, Boolean topLevel) at Xamarin.Android.Tasks.ResolveAssemblies.Execute(DirectoryAssemblyResolver resolver)

I also get a warning about the targeted project:

Package 'iridium.db.sqlite 2.2.1.530' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.

Does this mean that I have to implement a context in each platform and lose the shared code? Can I create a really cross-platform solution with Iridium?

[spiff123]

I tried the same with a PCL instead of a .net standard shared project and this works. I guess the iridium nuget is missing .net standard support - would be nice if this can be added.

[activa]

It works the same in PCL and .NETStandard projects.

If you're using Iridium in a mobile app that has a shared library (like you would with Xamarin Forms for example), the Sqlite data provider should be instantiated in the platform-specific projects, not in the shared library. There are several ways this can then be done, but the easiest way is to use dependency injection.

In your platform-specific projects:

ServiceRepository.Register(new SqliteDataProvider(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "myIridium.db"));

In your shared project, you define the context like this:

public class MyIridiumContext : StorageContext
  {
    public MyIridiumContext (IDataProvider provider) : base(provider)
    {
    }

    public IDataSet<Family> Family { get; set; }
  }

To use the context:

var context = ServiceRepository.Get<MyIridiumContext>();

[spiff123]

So the point is the "new SqliteDataProvider" has to be placed in the platform specific project (iOS/Android) so that the correct sqlite dll is pulled (in the .net standard assembly it pulls alway the sqlite win32 dll...)

Shouldn't there be a register call for "MyIridiumContext" in the snippet above - and a Path.Combine as parameter to SqliteDataProvider.

It works - thanks for the hint!

There are still 2 warnings left:

xy.csproj: Warning NU1603: iridium.db.sqlite 2.2.1.530 depends on iridium (>= 2.2.1) but iridium 2.2.1 was not found. An approximate best match of iridium 2.2.1.530 was resolved. (NU1603)

xy.csproj: Warning NU1701: Package 'iridium.db.sqlite 2.2.1.530' was restored using '.NETFramework,Version=v4.6.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project. (NU1701)

The second one brought me to the question if the nuget can be repackaged..

[activa]

You can ignore the first warning. The 2nd warning is because you referenced iridium.db.sqlite in the shared project. It should only reference the iridium package.

As for your ServiceRepository comment: you're right. If you use ServiceRepository.Get<MyIridiumContext>(), you should register it first by calling ServiceRepository.Register<MyIridiumContext>(). If you call ServiceRepository.Create<MyIridiumContext>(), registering the class is not required but it will create a new context every time you call Create() instead of reusing a single instance.

[spiff123]

Changed the shared/.net standard dependency to iridium and both warnings are gone. Great - thanks!

[spiff123]

@nologinatgit sorry for capturing your issue

[activa]

See also http://iridiumdb.com/docs/iridium/multiplatform