问题 无法从未打开的数据库创建命令

你正在进行同步阻塞调用 .Wait() 和 .Result 与异步API混合时可能会导致死锁。

SQLiteAsyncConnection 本来是用来异步使用的。

一个常见的工作是创建事件处理程序，以允许进行异步非阻塞调用。

例如，在打电话时 CreateTableAsync 在存储库中

public class Repository<T> : IRepository<T> where T : Entity, new() {
     private readonly SQLiteAsyncConnection _db;

    public Repository(string dbPath) {
        _db = new SQLiteAsyncConnection(dbPath);
        createTable += onCreateTable; //Subscribe to event
        createTable(this, EventArgs.Empty); //Raise event
    }

    private event EventHandler createTable = delegate { };
    private async void onCreateTable(object sender, EventArgs args) {
        createTable -= onCreateTable; //Unsubscribe from event
        await _db.CreateTableAsync<T>(); //async non blocking call
    }

    //...
}

存储库抽象似乎具有异步API，但存在同步调用。

再次，这可能会导致死锁，不建议。

如果意图是具有响应式UI或使用，则需要将代码重构为异步 SQLite.Net非同步版本，用于进行同步调用。

将URL活动重构为异步将按照与上面相同的格式进行重构。

protected override void OnCreate(Bundle bundle) {
    base.OnCreate(bundle);
    creating += onCreateCore; //subscribe to event
    creating(this, EventArgs.Empty); //raise event
}

private event EventHandler creating = delegate { };
private async void onCreateCore(object sender, EventArgs args) {
    creating -= onCreateCore; //unsubscribe to event
    var url = Intent.Data.ToString();
    var split = url.Split(new[] { "ombi://", "_" }, StringSplitOptions.RemoveEmptyEntries);
    if (split.Length > 1) {
        var dbLocation = new FileHelper().GetLocalFilePath("ombi.db3");
        var repo = new Repository<OmbiMobile.Models.Entities.Settings>(dbLocation);
        var settings = await repo.Get();
        foreach (var s in settings) {
            var i = await repo.Delete(s);
        }
        repo.Save(new Settings {
            AccessToken = split[1],
            OmbiUrl = split[0]
        });
    }

    Intent startup = new Intent(this, typeof(MainActivity));
    StartActivity(startup);
    Finish();
}

UPDATE

同样从设计的角度来看，连接的初始化应该从存储库中反转出来并在外部进行管理（SRP）。

public interface ISQLiteAsyncProvider {
    SQLiteAsyncConnection GetConnection();
}

public class DefaultSQLiteAsyncProvider : ISQLiteAsyncProvider {
    private readonly Lazy<SQLiteAsyncConnection> connection;

    public DefaultSQLiteAsyncProvider(string path) {
        connection = new Lazy<SQLiteAsyncConnection>(() => new SQLiteAsyncConnection(path));
    }

    public SQLiteAsyncConnection GetConnection() {
        return connection.Value;
    }
}

使用的连接的异步延迟初始化的想法

/// <summary>
/// Provides support for asynchronous lazy initialization.
/// </summary>
/// <typeparam name="T"></typeparam>
public class LazyAsync<T> : Lazy<Task<T>> {
    /// <summary>
    ///  Initializes a new instance of the LazyAsync`1 class. When lazy initialization
    ///  occurs, the specified initialization function is used.
    /// </summary>
    /// <param name="valueFactory">The delegate that is invoked to produce the lazily initialized Task when it is needed.</param>
    public LazyAsync(Func<Task<T>> valueFactory) :
        base(() => Task.Run(valueFactory)) { }
}

这使得现在可以重构存储库以使用延迟初始化，这允许删除存储库中的事件处理程序

public class Repository<T> : IRepository<T> where T : Entity, new() {

    public Repository(ISQLiteAsyncProvider provider) {
        this.connection = new LazyAsync<SQLiteAsyncConnection>(await () => {
            var db = provider.GetConnection();
            await db.CreateTableAsync<T>();
            return db;
        });
    }

    private readonly LazyAsync<SQLiteAsyncConnection> connection;

    public async Task<List<T>> Get() {
        var _db = await connection.Value;
        return await _db.Table<T>().ToListAsync();
    }

    public async Task<T> Get(int id) {
        var _db = await connection.Value;
        return await _db.Table<T>().Where(x => x.Id == id).FirstOrDefaultAsync();
    }

    public async Task<int> Save(T entity) {
        var _db = await connection.Value;
        return entity.Id == 0 
            ? await _db.InsertAsync(entity) 
            : await_db.UpdateAsync(entity);
    }

    public async Task<int> Delete(T entity) {
        var _db = await connection.Value;
        return await _db.DeleteAsync(entity);
    }

    public void Dispose() {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing) {
        if (disposing) {
            // get rid of managed resources
        }
        // get rid of unmanaged resources
    }
}

并注册了

// same instance should be used for other repositories
var provider = new DefaultSQLiteAsyncProvider(dbPath); 
var settingsRepository = new Repository<Settings>(provider);
FreshIOC.Container.Register<IRepository<Settings>>(settingsRepository);