In EF7, SqLite unable to load spatialite using the NetTopologySuite Package

[woodmeister]

Hi,

In EF 7 I using the Microsoft.EntityFrameworkCore.Sqlite.NetTopologySuite package a simple example does not seem to be able to load the spatialite library

I get "Microsoft.Data.Sqlite.SqliteException: 'SQLite Error 1: ''.'" implying sqlite has returned an error code, but not given any more information about it.

This was all working fine in EF 6

Stacktrace:-

 	 	Microsoft.Data.Sqlite.dll!Microsoft.Data.Sqlite.SqliteConnection.LoadExtensionCore(string file, string proc)	Unknown
 	Microsoft.Data.Sqlite.dll!Microsoft.Data.Sqlite.SqliteConnection.LoadExtension(string file, string proc)	Unknown
 	Microsoft.EntityFrameworkCore.Sqlite.dll!Microsoft.EntityFrameworkCore.Infrastructure.SpatialiteLoader.Load(System.Data.Common.DbConnection connection)	Unknown
 	Microsoft.EntityFrameworkCore.Sqlite.dll!Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal.SqliteRelationalConnection.InitializeDbConnection(System.Data.Common.DbConnection connection)	Unknown
 	Microsoft.EntityFrameworkCore.Sqlite.dll!Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal.SqliteRelationalConnection.SqliteRelationalConnection(Microsoft.EntityFrameworkCore.Storage.RelationalConnectionDependencies dependencies, Microsoft.EntityFrameworkCore.Storage.IRawSqlCommandBuilder rawSqlCommandBuilder, Microsoft.EntityFrameworkCore.Diagnostics.IDiagnosticsLogger<Microsoft.EntityFrameworkCore.DbLoggerCategory.Infrastructure> logger)	Unknown

Example code:-

var sqliteConnection = new SqliteConnection($"DataSource=c:\\temp\\testdb.db");
var _connection = sqliteConnection;
_connection.Open();

var optionsBuilder = new DbContextOptionsBuilder<DbContext>();
optionsBuilder.UseSqlite(_connection, arg => arg.UseNetTopologySuite());

[ajcvickers]

See https://learn.microsoft.com/en-us/ef/core/providers/sqlite/spatial#installing-spatialite

[woodmeister]

This on windows, so it should be pulled in by nuget? The spatialite binaries appear to be present in the runtimes folder as they were in the old version.

[woodmeister]

Further update,

This is my project file:-

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net7.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
	  <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="7.0.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.NetTopologySuite" Version="7.0.0" />
  </ItemGroup>

</Project>

If I change to net6.0 and 6.0.0 for the packages then it works, with net7.0 I get the error above.

[stefanlenselink]

I faced the same issue and came up with the following work-a-round, which is working for me (.net 7 / EF Core 7 / Windows):

In my database context in the OnConfiguring call:

protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
      base.OnConfiguring(options);

      options.UseSqlite($"Data Source={m_SQLiteDBPath}",
      o =>
      {
        o.UseNetTopologySuite();
        var infrastructure = (IDbContextOptionsBuilderInfrastructure)options;
#pragma warning disable EF1001
        var sqliteExtension = options.Options.FindExtension<SqliteOptionsExtension>() ?? new SqliteOptionsExtension();

        //We need to disable LoadSpatialite but it's not provided as an option externally we need to dig into the internals...
        infrastructure.AddOrUpdateExtension(sqliteExtension.WithLoadSpatialite(false));
#pragma warning restore EF1001
      });
    }

I use a IDbContextFactory to create / load a new database context. I have p/invoke definition inside the class:

[DllImport("mod_spatialite", CallingConvention = CallingConvention.Cdecl)]
static extern IntPtr spatialite_version();

In the the CreateDbContext() call I have:

          //Prime the spationlite module, trigger a 'useless' call to trigger the load of the module in mem.
          spatialite_version();
          var connection = m_DatabaseContext.Database.GetDbConnection();
          if (connection is SqliteConnection sqliteConnection)
          {
            //We trigger an open and keep the connection open so we load the module
            sqliteConnection.Open();
            //We need to enable extensions otherwise we receive an unathorized exception
            sqliteConnection.EnableExtensions(true);
            var sqliteCommand = new SqliteCommand(@"SELECT load_extension('mod_spatialite');", sqliteConnection);
            sqliteCommand.ExecuteReader(); //We don't read anything..we don't care but it's a Select so we need to perform a Reader.
          }

Probably this can be simplified, but I noticed the p/invoke call to spatialite_version triggers the load of the module in mem, and the dynamic load of the mod_spatialite module did the trick (see https://www.gaia-gis.it/fossil/libspatialite/wiki?name=mod_spatialite).

EF Core internally use the sqlite function call to load an extension that seem to fail without any (reasonable) reason.

btw; same PackageReferences as @woodmeister

[woodmeister]

Workaround good for me too.

I needed to put the sqlitecommand in a using so it get's disposed, otherwise there are problems with the machinery later on.

[BartjeD]

We also encountered this issue with the topology suite and SQLITE in EF Core 7.

We altered the above work around to use:

[LibraryImport("mod_spatialite")]
[UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
private static partial IntPtr spatialite_version();

Which I can't take credit for - it's a suggestion by Visual Studio.

[bricelam]

Hmm... It looks like our change from using sqlite3_enable_load_extension() to sqlite3_db_config(SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION) broke SpatiaLite. I wonder if it loads additional extensions using SELECT load_extension().

Calling connection.EnableExtensions() before passing it to UseSqlite might work around the issue.

I'll keep investigating.