首先，这是我的意图：
- 在 SQLite 上创建 DbContext
- 从/向它读取和写入
- 关闭上下文
- 将文件移动到另一个位置
第1-3点工作完美。当我尝试移动数据库时，问题就开始了。我收到一条错误消息，指出：
'The process cannot access the file because it is being used by another process.'
我该如何解决这个问题？
首先，我创建一个上下文。我必须在几种方法中使用它，并且我不想每次需要它时都创建它。所以我将它存储为成员。
_sqliteContext = new SqlLiteContext(sqliteContextName);
然后我想访问一个名为sync并获取其最新条目的表。
var sync = _sqliteContext.Syncs.OrderByDescending(s => s.Date);
_lastSync = sync.Any() ? sync.First().Date : new DateTime(0);
而已。然后我关闭上下文。
_sqliteContext.Dispose();
并尝试移动文件。
File.Move(sqliteUploadLocation, sqliteDownloadLocation);
这是我得到异常的地方。
当我用插入替换选择时，如下所示：
var sync = new Sync { Id = Guid.NewGuid().ToString(), Date = DateTime.Now };
_sqliteContext.Syncs.Add(sync);
_sqliteContext.SaveChanges();
这行得通，我可以移动数据库。任何想法为什么我的选择不释放其锁定？
更新
// Start synchronisation.
new SyncManager(mssqlString, sqliteUploadLocation).Start();
// Move file from upload to download location.
try
{
File.Move(sqliteUploadLocation, sqliteDownloadLocation);
}
catch (Exception ex)
{
Console.WriteLine("Moving failed!");
Console.WriteLine(ex.Message);
}
public void Start()
{
// Create connection string for the sqlite database.
const string sqliteContextName = "SqLiteContext";
var sqliteConnStringSettings = new ConnectionStringSettings
{
Name = sqliteContextName,
ConnectionString = "Data Source=" + _sqliteUploadLocation + ";Version=3;BinaryGUID=False;",
ProviderName = "System.Data.SQLite"
};
// Read configuration, delete available connection strings and add ours.
var conf = ConfigurationManager.OpenMachineConfiguration();
var connStrings = conf.ConnectionStrings;
connStrings.ConnectionStrings.Remove(sqliteContextName);
connStrings.ConnectionStrings.Add(sqliteConnStringSettings);
try
{
conf.Save(ConfigurationSaveMode.Minimal);
}
catch (Exception)
{
// Insufficient rights to save.
return;
}
ConfigurationManager.RefreshSection("connectionStrings");
// Create connection to the sqlite database.
_sqliteContext = new SqlLiteContext(sqliteContextName);
// Create connection to the mssql database.
_mssqlContext = new MsSqlContext(_mssqlConnString);
// Read last sync date.
var sync = _sqliteContext.Syncs.OrderByDescending(s => s.Date);
_lastSync = sync.Any() ? sync.First().Date : new DateTime(0);
// Synchronize tables.
//SyncTablePerson();
//SyncTableAddressAllocation();
// Creates an entry for this synchronisation.
CreateSyncEntry();
// Release resources.
_sqliteContext.Dispose();
_mssqlContext.Dispose();
}
private void CreateSyncEntry()
{
var sync = new Sync { Id = Guid.NewGuid().ToString(), Date = DateTime.Now };
_sqliteContext.Syncs.Add(sync);
_sqliteContext.SaveChanges();
}
更新 2
public class SqlLiteContext : Context
{
public DbSet<Sync> Syncs { get; set; }
public SqlLiteContext(string connectionString)
: base(connectionString)
{
Database.SetInitializer(new NoOperationStrategy<SqlLiteContext>());
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new PersonConfig());
modelBuilder.Configurations.Add(new AddressAllocationConfig());
modelBuilder.Configurations.Add(new AddressConfig());
modelBuilder.Configurations.Add(new SyncConfig());
}
}
public class NoOperationStrategy<T> : IDatabaseInitializer<T> where T : DbContext
{
public void InitializeDatabase(T context)
{
}
}
public abstract class Context : DbContext
{
public DbSet<Person> Persons { get; set; }
public DbSet<AddressAllocation> AddressAllocations { get; set; }
public DbSet<Address> Addresses { get; set; }
protected Context(string connectionString)
: base(connectionString)
{
}
}
使用重构
using (var sqliteContext = new SqlLiteContext(_sqliteContextName))
{
// Read last sync date.
var sync = sqliteContext.Syncs.Select(s => s).OrderByDescending(s => s.Date);
var lastSync = sync.Any() ? sync.First().Date : new DateTime(1900, 1, 1);
using (var mssqlContext = new MsSqlContext(_mssqlConnString))
{
SyncTablePerson(sqliteContext, mssqlContext, lastSync);
SyncTableAddressAllocation(sqliteContext, mssqlContext, lastSync);
// Save server changes.
mssqlContext.SaveChanges();
}
// Creates an entry for this synchronisation.
sqliteContext.Syncs.Add(new Sync { Id = Guid.NewGuid().ToString(), Date = DateTime.Now });
// Save local changes.
sqliteContext.SaveChanges();
}