Question: Unity Support

[rdcm]

Hi!

Could the SQLite-net be used in Unity projects?

In the official description Unity not mentioned.

SQLite-net is an open source, minimal library to allow .NET, .NET Core, and Mono applications to store data in SQLite 3 databases. It was first designed to work with Xamarin.iOS, but has since grown up to work on all the platforms (Xamarin.*, .NET, UWP, Azure, etc.).

But I see a merged fix for IL2CPP:
#993

[shiena]

@rdcm

• mac/iOS : just copy SQLite.cs to your project
• Windows: just copy SQLite.cs and the official sqlite3.dll to your project.
• Android: copy SQLite.cs and the official sqlite-android-*.aar to your project and change the LibraryPath of SQLite.cs.

diff --git a/src/SQLite.cs b/src/SQLite.cs
--- a/src/SQLite.cs	(date 1618732310971)
+++ b/src/SQLite.cs	(date 1618732310971)
@@ -4356,7 +4356,11 @@
 			Serialized = 3
 		}
 
+#if UNITY_ANDROID && !UNITY_EDITOR
+		const string LibraryPath = "sqliteX";
+#else
 		const string LibraryPath = "sqlite3";
+#endif
 
 #if !USE_CSHARP_SQLITE && !USE_WP8_NATIVE_SQLITE && !USE_SQLITEPCL_RAW
 		[DllImport(LibraryPath, EntryPoint = "sqlite3_threadsafe", CallingConvention=CallingConvention.Cdecl)]

[gindemit]

Hey @shiena, can you please explain, or send some information how SQLite works on Mac/iOS? Why the native library is not necessary?

[shiena]

@khindemit
Mac/iOS includes sqlite3 so it works without adding native libraries.
On my macOS Catalina, /usr/lib/libsqlite3.dylib exists.

[wiverson]

Just to add a comment after doing some research - on macOS, if the library asked for in sqlite-net is "sqlite3" macOS will automatically look for a library with libsqlite3.dylib, which is included in the library lookup path by default. The lib prefix and .dylib are magic strings added to the lookup.

[wiverson]

Even more magic - I just checked my macOS Monterey 12.0.1 M1 install, and it's now /usr/lib/sqlite3 alone. Interesting.

[shiena]

I forgot that DllImport should be __Internal in iOS.
So the patch is as follows, along with the one for Android.
https://docs.unity3d.com/2022.1/Documentation/Manual/NativePlugins.html

diff --git a/src/SQLite.cs b/src/SQLite.cs
index e5712f3..dc9e0d4 100644
--- a/src/SQLite.cs
+++ b/src/SQLite.cs
@@ -4468,7 +4468,13 @@ namespace SQLite
 			Serialized = 3
 		}
 
+#if UNITY_IOS && !UNITY_EDITOR
+		const string LibraryPath = "__Internal";
+#elif UNITY_ANDROID && !UNITY_EDITOR
+		const string LibraryPath = "sqliteX";
+#else
 		const string LibraryPath = "sqlite3";
+#endif
 
 #if !USE_CSHARP_SQLITE && !USE_WP8_NATIVE_SQLITE && !USE_SQLITEPCL_RAW
 		[DllImport(LibraryPath, EntryPoint = "sqlite3_threadsafe", CallingConvention=CallingConvention.Cdecl)]

[heshuimu]

@shiena
For iOS, If the intent is using the system-provided libsqlite3, LibraryPath should be kept as sqlite3.
__Internal is only for linking extern methods with statically-linked native functions in Unity IL2CPP. Unity's documentation was not updated to include the fact that dynamic linking was supported since iOS 8.
However, if the Unity project integrates SQLite using static library or source code, then LibraryPath should be kept as __Internal for all platforms, including Android.