StockSharp/Ecng.Datav1.0.423

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.NET 10.0.NET 6.0

Ecng system framework

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Published

Mar 3, 2026

Get Started

$ dotnet add package Ecng.Data

Readme

Ecng.Data

A lightweight library providing common abstractions for data access layers, including database connection management, caching, and provider abstractions.

Overview
Installation
Key Features
Core Components
Usage Examples
API Reference
Advanced Scenarios

Overview

Ecng.Data provides a simple yet powerful abstraction layer for managing database connections in .NET applications. It focuses on:

Reusable connection definitions - Define connections once, use them everywhere
Connection caching - Automatically manage and deduplicate connection configurations
Persistence - Save and load connection configurations
Provider abstraction - Work with multiple database providers through a unified interface
Event-driven architecture - React to connection lifecycle events

This library is designed to be database-agnostic and works seamlessly with various data access technologies, including Linq2Db, ADO.NET, and other ORMs.

Installation

Add a reference to the Ecng.Data project or NuGet package in your project:

<ItemGroup>
  <ProjectReference Include="..\Ecng\Data\Data.csproj" />
</ItemGroup>

For Linq2Db integration, also add:

<ItemGroup>
  <ProjectReference Include="..\Ecng\Data.Linq2db\Data.Linq2db.csproj" />
</ItemGroup>

Key Features

DatabaseConnectionPair - Encapsulates provider type and connection string
DatabaseConnectionCache - Thread-safe cache for managing connection definitions
IDatabaseProviderRegistry - Interface for provider discovery and connection verification
IPersistable - Built-in serialization support for saving/loading configurations
Event notifications - Track connection creation, deletion, and cache updates
Equality comparison - Case-insensitive comparison of connection pairs

Core Components

DatabaseConnectionPair

Represents a database connection configuration with a provider and connection string.

public class DatabaseConnectionPair : NotifiableObject, IPersistable
{
    public string Provider { get; set; }
    public string ConnectionString { get; set; }
    public string Title { get; }  // Read-only: "({Provider}) {ConnectionString}"
}

DatabaseConnectionCache

A thread-safe cache for managing database connection pairs with automatic deduplication.

public class DatabaseConnectionCache : IPersistable
{
    public IEnumerable<DatabaseConnectionPair> Connections { get; }
    public DatabaseConnectionPair GetOrAdd(string provider, string connectionString);
    public bool DeleteConnection(DatabaseConnectionPair connection);

    public event Action<DatabaseConnectionPair> ConnectionCreated;
    public event Action<DatabaseConnectionPair> ConnectionDeleted;
    public event Action Updated;
}

IDatabaseProviderRegistry

Interface for database provider management and connection verification.

public interface IDatabaseProviderRegistry
{
    string[] Providers { get; }
    void Verify(DatabaseConnectionPair connection);
}

Usage Examples

Basic Connection Management

Creating a Connection Pair

using Ecng.Data;

// Create a connection pair
var pair = new DatabaseConnectionPair
{
    Provider = "SqlServer",
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

// Display the connection
Console.WriteLine(pair.Title);
// Output: (SqlServer) Server=localhost;Database=MyDb;Trusted_Connection=True;

Using with Linq2Db

using Ecng.Data;
using LinqToDB;
using LinqToDB.Data;

// Create connection pair
var pair = new DatabaseConnectionPair
{
    Provider = ProviderName.SqlServer,
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

// Create and use a database connection
using (var connection = pair.CreateConnection())
{
    // Execute queries using Linq2Db
    var users = connection.GetTable<User>()
        .Where(u => u.IsActive)
        .ToList();

    // Execute SQL commands
    connection.Execute("UPDATE Users SET LastLogin = GETDATE() WHERE Id = @id",
        new { id = 123 });
}

Connection Caching

Basic Cache Operations

using Ecng.Data;
using LinqToDB;

// Create a connection cache
var cache = new DatabaseConnectionCache();

// Add connections to cache (or retrieve if already exists)
var sqlServerConn = cache.GetOrAdd(
    ProviderName.SqlServer,
    "Server=localhost;Database=MyDb;Trusted_Connection=True;"
);

var sqliteConn = cache.GetOrAdd(
    ProviderName.SQLite,
    "Data Source=mydb.sqlite;Version=3;"
);

var mysqlConn = cache.GetOrAdd(
    ProviderName.MySql,
    "Server=localhost;Database=MyDb;Uid=root;Pwd=password;"
);

// Retrieve all cached connections
foreach (var conn in cache.Connections)
{
    Console.WriteLine($"Cached: {conn.Title}");
}

// Remove a connection
cache.DeleteConnection(sqliteConn);

Automatic Deduplication

var cache = new DatabaseConnectionCache();

// Adding the same connection twice returns the same instance
var conn1 = cache.GetOrAdd("SqlServer", "Server=localhost;Database=MyDb");
var conn2 = cache.GetOrAdd("SqlServer", "Server=localhost;Database=MyDb");

Console.WriteLine(ReferenceEquals(conn1, conn2)); // True
Console.WriteLine(cache.Connections.Count()); // 1

// Case-insensitive comparison
var conn3 = cache.GetOrAdd("SQLSERVER", "server=localhost;database=mydb");
Console.WriteLine(ReferenceEquals(conn1, conn3)); // True

Event Handling

Monitoring Connection Lifecycle

var cache = new DatabaseConnectionCache();

// Subscribe to events
cache.ConnectionCreated += conn =>
{
    Console.WriteLine($"Connection created: {conn.Title}");
    // Log to file, notify UI, etc.
};

cache.ConnectionDeleted += conn =>
{
    Console.WriteLine($"Connection deleted: {conn.Title}");
    // Clean up resources, update UI, etc.
};

cache.Updated += () =>
{
    Console.WriteLine($"Cache updated. Total connections: {cache.Connections.Count()}");
    // Refresh UI, trigger backup, etc.
};

// Trigger events
var pair = cache.GetOrAdd("SqlServer", "Server=localhost");
// Output: Connection created: (SqlServer) Server=localhost
//         Cache updated. Total connections: 1

cache.DeleteConnection(pair);
// Output: Connection deleted: (SqlServer) Server=localhost
//         Cache updated. Total connections: 0

Building a Connection Manager UI

public class ConnectionManager
{
    private readonly DatabaseConnectionCache _cache;

    public ConnectionManager()
    {
        _cache = new DatabaseConnectionCache();

        // Wire up events to update UI
        _cache.ConnectionCreated += OnConnectionCreated;
        _cache.ConnectionDeleted += OnConnectionDeleted;
        _cache.Updated += OnCacheUpdated;
    }

    public void AddConnection(string provider, string connectionString)
    {
        _cache.GetOrAdd(provider, connectionString);
    }

    public void RemoveConnection(DatabaseConnectionPair connection)
    {
        _cache.DeleteConnection(connection);
    }

    public IEnumerable<DatabaseConnectionPair> GetAllConnections()
    {
        return _cache.Connections;
    }

    private void OnConnectionCreated(DatabaseConnectionPair conn)
    {
        // Update UI list
        // _listView.Items.Add(conn);
    }

    private void OnConnectionDeleted(DatabaseConnectionPair conn)
    {
        // Update UI list
        // _listView.Items.Remove(conn);
    }

    private void OnCacheUpdated()
    {
        // Refresh status bar
        // _statusLabel.Text = $"{_cache.Connections.Count()} connections";
    }
}

Persistence

Saving and Loading Connections

using Ecng.Data;
using Ecng.Serialization;
using LinqToDB;

// Create and populate cache
var cache = new DatabaseConnectionCache();
cache.GetOrAdd(ProviderName.SqlServer, "Server=localhost;Database=MyDb");
cache.GetOrAdd(ProviderName.SQLite, "Data Source=mydb.sqlite");

// Save to JSON
var serializer = new JsonSerializer<DatabaseConnectionCache>();
var json = serializer.Serialize(cache);
File.WriteAllText("connections.json", json);

// Load from JSON
var jsonContent = File.ReadAllText("connections.json");
var loadedCache = serializer.Deserialize(jsonContent);

// Verify loaded data
foreach (var conn in loadedCache.Connections)
{
    Console.WriteLine($"Loaded: {conn.Title}");
}

Custom Persistence Storage

using Ecng.Serialization;

// Save to custom storage
var cache = new DatabaseConnectionCache();
cache.GetOrAdd("SqlServer", "Server=localhost");

var storage = cache.Save();
// storage is a SettingsStorage object that can be serialized to various formats

// Load from custom storage
var newCache = new DatabaseConnectionCache();
newCache.Load(storage);

Application Settings Integration

public class AppSettings
{
    private readonly DatabaseConnectionCache _connectionCache = new();
    private readonly string _settingsFile = "appsettings.json";

    public DatabaseConnectionCache Connections => _connectionCache;

    public void Load()
    {
        if (File.Exists(_settingsFile))
        {
            var serializer = new JsonSerializer<SettingsStorage>();
            var storage = serializer.Deserialize(File.ReadAllText(_settingsFile));
            _connectionCache.Load(storage);
        }
    }

    public void Save()
    {
        var storage = new SettingsStorage();
        _connectionCache.Save(storage);

        var serializer = new JsonSerializer<SettingsStorage>();
        File.WriteAllText(_settingsFile, serializer.Serialize(storage));
    }
}

// Usage
var settings = new AppSettings();
settings.Load();

// Add connections
settings.Connections.GetOrAdd("SqlServer", "Server=localhost");

// Save changes
settings.Save();

Provider Registry

Implementing a Provider Registry

using Ecng.Data;
using LinqToDB;

public class CustomDatabaseProviderRegistry : IDatabaseProviderRegistry
{
    public string[] Providers { get; } =
    [
        ProviderName.SqlServer,
        ProviderName.SQLite,
        ProviderName.MySql,
        ProviderName.PostgreSQL,
        ProviderName.Oracle
    ];

    public void Verify(DatabaseConnectionPair connection)
    {
        try
        {
            using var db = connection.CreateConnection();
            using var conn = db.DataProvider.CreateConnection(db.ConnectionString);
            conn.Open();
            Console.WriteLine($"Connection to {connection.Provider} verified successfully");
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException(
                $"Failed to verify connection to {connection.Provider}: {ex.Message}",
                ex
            );
        }
    }
}

Using the Provider Registry

var registry = new CustomDatabaseProviderRegistry();

// Display available providers
Console.WriteLine("Available providers:");
foreach (var provider in registry.Providers)
{
    Console.WriteLine($"  - {provider}");
}

// Verify a connection
var connection = new DatabaseConnectionPair
{
    Provider = ProviderName.SqlServer,
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

try
{
    registry.Verify(connection);
    Console.WriteLine("Connection is valid!");
}
catch (Exception ex)
{
    Console.WriteLine($"Connection verification failed: {ex.Message}");
}

API Reference

DatabaseConnectionPair

Member	Type	Description
`Provider`	`string`	The database provider type (e.g., "SqlServer", "SQLite", "MySql")
`ConnectionString`	`string`	The connection string for the database
`Title`	`string`	Read-only formatted string: "({Provider}) {ConnectionString}"
`Load(SettingsStorage)`	`void`	Loads the pair from settings storage
`Save(SettingsStorage)`	`void`	Saves the pair to settings storage
`Equals(object)`	`bool`	Compares pairs using case-insensitive comparison
`GetHashCode()`	`int`	Returns case-insensitive hash code

DatabaseConnectionCache

Member	Type	Description
`Connections`	`IEnumerable<DatabaseConnectionPair>`	Gets all cached connection pairs
`GetOrAdd(string, string)`	`DatabaseConnectionPair`	Gets existing or adds new connection pair
`DeleteConnection(DatabaseConnectionPair)`	`bool`	Removes connection from cache
`Load(SettingsStorage)`	`void`	Loads connections from storage
`Save(SettingsStorage)`	`void`	Saves connections to storage
`ConnectionCreated`	`event Action<DatabaseConnectionPair>`	Raised when a new connection is added
`ConnectionDeleted`	`event Action<DatabaseConnectionPair>`	Raised when a connection is removed
`Updated`	`event Action`	Raised when the cache is modified

IDatabaseProviderRegistry

Member	Type	Description
`Providers`	`string[]`	Gets the list of available database providers
`Verify(DatabaseConnectionPair)`	`void`	Verifies a connection by attempting to open it

Extension Methods (Linq2Db Integration)

Method	Return Type	Description
`CreateConnection(this DatabaseConnectionPair)`	`DataConnection`	Creates a Linq2Db DataConnection from the pair

Advanced Scenarios

Pooling Multiple Database Connections

public class MultiDatabaseService
{
    private readonly DatabaseConnectionCache _cache;

    public MultiDatabaseService()
    {
        _cache = new DatabaseConnectionCache();

        // Set up connections for different databases
        _cache.GetOrAdd(ProviderName.SqlServer, "Server=localhost;Database=MainDb;...");
        _cache.GetOrAdd(ProviderName.SQLite, "Data Source=cache.sqlite;...");
        _cache.GetOrAdd(ProviderName.MySql, "Server=localhost;Database=Analytics;...");
    }

    public void ExecuteOnAll(Action<DatabaseConnectionPair> action)
    {
        foreach (var connection in _cache.Connections)
        {
            action(connection);
        }
    }

    public T ExecuteQuery<T>(string provider, Func<DataConnection, T> query)
    {
        var pair = _cache.Connections.FirstOrDefault(c =>
            c.Provider.EqualsIgnoreCase(provider));

        if (pair == null)
            throw new InvalidOperationException($"Provider {provider} not found");

        using var connection = pair.CreateConnection();
        return query(connection);
    }
}

// Usage
var service = new MultiDatabaseService();

var sqlServerUsers = service.ExecuteQuery(ProviderName.SqlServer, db =>
    db.GetTable<User>().ToList()
);

service.ExecuteOnAll(pair =>
{
    using var conn = pair.CreateConnection();
    Console.WriteLine($"Testing {pair.Provider}...");
    conn.Execute("SELECT 1");
});

Connection Testing and Health Checks

public class ConnectionHealthChecker
{
    private readonly DatabaseConnectionCache _cache;
    private readonly IDatabaseProviderRegistry _registry;

    public ConnectionHealthChecker(
        DatabaseConnectionCache cache,
        IDatabaseProviderRegistry registry)
    {
        _cache = cache;
        _registry = registry;
    }

    public Dictionary<DatabaseConnectionPair, bool> CheckAllConnections()
    {
        var results = new Dictionary<DatabaseConnectionPair, bool>();

        foreach (var connection in _cache.Connections)
        {
            try
            {
                _registry.Verify(connection);
                results[connection] = true;
                Console.WriteLine($"✓ {connection.Title}");
            }
            catch (Exception ex)
            {
                results[connection] = false;
                Console.WriteLine($"✗ {connection.Title}: {ex.Message}");
            }
        }

        return results;
    }

    public async Task<bool> MonitorConnectionAsync(
        DatabaseConnectionPair connection,
        TimeSpan interval,
        CancellationToken cancellationToken)
    {
        while (!cancellationToken.IsCancellationRequested)
        {
            try
            {
                _registry.Verify(connection);
                await Task.Delay(interval, cancellationToken);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Connection lost: {ex.Message}");
                return false;
            }
        }

        return true;
    }
}

Dynamic Configuration Management

public class DynamicConnectionManager
{
    private readonly DatabaseConnectionCache _cache;
    private readonly IConfiguration _configuration;

    public DynamicConnectionManager(IConfiguration configuration)
    {
        _configuration = configuration;
        _cache = new DatabaseConnectionCache();
        LoadFromConfiguration();
    }

    private void LoadFromConfiguration()
    {
        var connections = _configuration
            .GetSection("DatabaseConnections")
            .GetChildren();

        foreach (var connConfig in connections)
        {
            var provider = connConfig["Provider"];
            var connectionString = connConfig["ConnectionString"];

            if (!string.IsNullOrEmpty(provider) &&
                !string.IsNullOrEmpty(connectionString))
            {
                _cache.GetOrAdd(provider, connectionString);
            }
        }
    }

    public void ReloadConfiguration()
    {
        // Clear and reload
        foreach (var conn in _cache.Connections.ToList())
        {
            _cache.DeleteConnection(conn);
        }

        LoadFromConfiguration();
    }

    public DatabaseConnectionPair GetConnection(string name)
    {
        return _cache.Connections.FirstOrDefault(c =>
            c.Title.Contains(name, StringComparison.OrdinalIgnoreCase)
        );
    }
}

// appsettings.json example:
// {
//   "DatabaseConnections": [
//     {
//       "Provider": "SqlServer",
//       "ConnectionString": "Server=localhost;Database=MyDb;..."
//     },
//     {
//       "Provider": "SQLite",
//       "ConnectionString": "Data Source=mydb.sqlite"
//     }
//   ]
// }

Thread-Safe Operations

public class ConcurrentConnectionManager
{
    private readonly DatabaseConnectionCache _cache;
    private readonly object _lock = new();

    public ConcurrentConnectionManager()
    {
        _cache = new DatabaseConnectionCache();
    }

    public DatabaseConnectionPair SafeGetOrAdd(string provider, string connectionString)
    {
        lock (_lock)
        {
            return _cache.GetOrAdd(provider, connectionString);
        }
    }

    public async Task<List<TResult>> ExecuteInParallel<TResult>(
        Func<DatabaseConnectionPair, TResult> operation)
    {
        var tasks = _cache.Connections
            .Select(conn => Task.Run(() => operation(conn)))
            .ToList();

        return (await Task.WhenAll(tasks)).ToList();
    }
}

// Usage
var manager = new ConcurrentConnectionManager();

// Execute queries in parallel across all databases
var results = await manager.ExecuteInParallel(pair =>
{
    using var conn = pair.CreateConnection();
    return conn.GetTable<User>().Count();
});

Console.WriteLine($"Total users across all databases: {results.Sum()}");

Best Practices

Always dispose connections: Use using statements when creating connections
Validate connection strings: Verify connections before using them in production
Use caching: Leverage DatabaseConnectionCache to avoid duplicate connection definitions
Handle events: Subscribe to cache events for logging and monitoring
Persist configurations: Save connection cache to disk for application state management
Thread safety: The cache is thread-safe, but always consider synchronization in multi-threaded scenarios
Security: Never hard-code connection strings; use configuration files or secure storage
Provider names: Use constants from LinqToDB.ProviderName for consistency

License

Part of the StockSharp project. See the main repository for license information.

Related Projects

Ecng.ComponentModel - Base component model and notification support
Ecng.Serialization - Serialization infrastructure used by this library
Ecng.Data.Linq2db - Linq2Db integration extensions

Total Downloads

617.7K

Compatibility

.NET 10.0

.NET 6.0

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1.0.423Latest

Mar 3, 2026

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Ecng.Data

A lightweight library providing common abstractions for data access layers, including database connection management, caching, and provider abstractions.

Overview
Installation
Key Features
Core Components
Usage Examples
API Reference
Advanced Scenarios

Overview

Ecng.Data provides a simple yet powerful abstraction layer for managing database connections in .NET applications. It focuses on:

Reusable connection definitions - Define connections once, use them everywhere
Connection caching - Automatically manage and deduplicate connection configurations
Persistence - Save and load connection configurations
Provider abstraction - Work with multiple database providers through a unified interface
Event-driven architecture - React to connection lifecycle events

This library is designed to be database-agnostic and works seamlessly with various data access technologies, including Linq2Db, ADO.NET, and other ORMs.

Installation

Add a reference to the Ecng.Data project or NuGet package in your project:

<ItemGroup>
  <ProjectReference Include="..\Ecng\Data\Data.csproj" />
</ItemGroup>

For Linq2Db integration, also add:

<ItemGroup>
  <ProjectReference Include="..\Ecng\Data.Linq2db\Data.Linq2db.csproj" />
</ItemGroup>

Key Features

DatabaseConnectionPair - Encapsulates provider type and connection string
DatabaseConnectionCache - Thread-safe cache for managing connection definitions
IDatabaseProviderRegistry - Interface for provider discovery and connection verification
IPersistable - Built-in serialization support for saving/loading configurations
Event notifications - Track connection creation, deletion, and cache updates
Equality comparison - Case-insensitive comparison of connection pairs

Core Components

DatabaseConnectionPair

Represents a database connection configuration with a provider and connection string.

public class DatabaseConnectionPair : NotifiableObject, IPersistable
{
    public string Provider { get; set; }
    public string ConnectionString { get; set; }
    public string Title { get; }  // Read-only: "({Provider}) {ConnectionString}"
}

DatabaseConnectionCache

A thread-safe cache for managing database connection pairs with automatic deduplication.

public class DatabaseConnectionCache : IPersistable
{
    public IEnumerable<DatabaseConnectionPair> Connections { get; }
    public DatabaseConnectionPair GetOrAdd(string provider, string connectionString);
    public bool DeleteConnection(DatabaseConnectionPair connection);

    public event Action<DatabaseConnectionPair> ConnectionCreated;
    public event Action<DatabaseConnectionPair> ConnectionDeleted;
    public event Action Updated;
}

IDatabaseProviderRegistry

Interface for database provider management and connection verification.

public interface IDatabaseProviderRegistry
{
    string[] Providers { get; }
    void Verify(DatabaseConnectionPair connection);
}

Usage Examples

Basic Connection Management

Creating a Connection Pair

using Ecng.Data;

// Create a connection pair
var pair = new DatabaseConnectionPair
{
    Provider = "SqlServer",
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

// Display the connection
Console.WriteLine(pair.Title);
// Output: (SqlServer) Server=localhost;Database=MyDb;Trusted_Connection=True;

Using with Linq2Db

using Ecng.Data;
using LinqToDB;
using LinqToDB.Data;

// Create connection pair
var pair = new DatabaseConnectionPair
{
    Provider = ProviderName.SqlServer,
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

// Create and use a database connection
using (var connection = pair.CreateConnection())
{
    // Execute queries using Linq2Db
    var users = connection.GetTable<User>()
        .Where(u => u.IsActive)
        .ToList();

    // Execute SQL commands
    connection.Execute("UPDATE Users SET LastLogin = GETDATE() WHERE Id = @id",
        new { id = 123 });
}

Connection Caching

Basic Cache Operations

using Ecng.Data;
using LinqToDB;

// Create a connection cache
var cache = new DatabaseConnectionCache();

// Add connections to cache (or retrieve if already exists)
var sqlServerConn = cache.GetOrAdd(
    ProviderName.SqlServer,
    "Server=localhost;Database=MyDb;Trusted_Connection=True;"
);

var sqliteConn = cache.GetOrAdd(
    ProviderName.SQLite,
    "Data Source=mydb.sqlite;Version=3;"
);

var mysqlConn = cache.GetOrAdd(
    ProviderName.MySql,
    "Server=localhost;Database=MyDb;Uid=root;Pwd=password;"
);

// Retrieve all cached connections
foreach (var conn in cache.Connections)
{
    Console.WriteLine($"Cached: {conn.Title}");
}

// Remove a connection
cache.DeleteConnection(sqliteConn);

Automatic Deduplication

var cache = new DatabaseConnectionCache();

// Adding the same connection twice returns the same instance
var conn1 = cache.GetOrAdd("SqlServer", "Server=localhost;Database=MyDb");
var conn2 = cache.GetOrAdd("SqlServer", "Server=localhost;Database=MyDb");

Console.WriteLine(ReferenceEquals(conn1, conn2)); // True
Console.WriteLine(cache.Connections.Count()); // 1

// Case-insensitive comparison
var conn3 = cache.GetOrAdd("SQLSERVER", "server=localhost;database=mydb");
Console.WriteLine(ReferenceEquals(conn1, conn3)); // True

Event Handling

Monitoring Connection Lifecycle

var cache = new DatabaseConnectionCache();

// Subscribe to events
cache.ConnectionCreated += conn =>
{
    Console.WriteLine($"Connection created: {conn.Title}");
    // Log to file, notify UI, etc.
};

cache.ConnectionDeleted += conn =>
{
    Console.WriteLine($"Connection deleted: {conn.Title}");
    // Clean up resources, update UI, etc.
};

cache.Updated += () =>
{
    Console.WriteLine($"Cache updated. Total connections: {cache.Connections.Count()}");
    // Refresh UI, trigger backup, etc.
};

// Trigger events
var pair = cache.GetOrAdd("SqlServer", "Server=localhost");
// Output: Connection created: (SqlServer) Server=localhost
//         Cache updated. Total connections: 1

cache.DeleteConnection(pair);
// Output: Connection deleted: (SqlServer) Server=localhost
//         Cache updated. Total connections: 0

Building a Connection Manager UI

public class ConnectionManager
{
    private readonly DatabaseConnectionCache _cache;

    public ConnectionManager()
    {
        _cache = new DatabaseConnectionCache();

        // Wire up events to update UI
        _cache.ConnectionCreated += OnConnectionCreated;
        _cache.ConnectionDeleted += OnConnectionDeleted;
        _cache.Updated += OnCacheUpdated;
    }

    public void AddConnection(string provider, string connectionString)
    {
        _cache.GetOrAdd(provider, connectionString);
    }

    public void RemoveConnection(DatabaseConnectionPair connection)
    {
        _cache.DeleteConnection(connection);
    }

    public IEnumerable<DatabaseConnectionPair> GetAllConnections()
    {
        return _cache.Connections;
    }

    private void OnConnectionCreated(DatabaseConnectionPair conn)
    {
        // Update UI list
        // _listView.Items.Add(conn);
    }

    private void OnConnectionDeleted(DatabaseConnectionPair conn)
    {
        // Update UI list
        // _listView.Items.Remove(conn);
    }

    private void OnCacheUpdated()
    {
        // Refresh status bar
        // _statusLabel.Text = $"{_cache.Connections.Count()} connections";
    }
}

Persistence

Saving and Loading Connections

using Ecng.Data;
using Ecng.Serialization;
using LinqToDB;

// Create and populate cache
var cache = new DatabaseConnectionCache();
cache.GetOrAdd(ProviderName.SqlServer, "Server=localhost;Database=MyDb");
cache.GetOrAdd(ProviderName.SQLite, "Data Source=mydb.sqlite");

// Save to JSON
var serializer = new JsonSerializer<DatabaseConnectionCache>();
var json = serializer.Serialize(cache);
File.WriteAllText("connections.json", json);

// Load from JSON
var jsonContent = File.ReadAllText("connections.json");
var loadedCache = serializer.Deserialize(jsonContent);

// Verify loaded data
foreach (var conn in loadedCache.Connections)
{
    Console.WriteLine($"Loaded: {conn.Title}");
}

Custom Persistence Storage

using Ecng.Serialization;

// Save to custom storage
var cache = new DatabaseConnectionCache();
cache.GetOrAdd("SqlServer", "Server=localhost");

var storage = cache.Save();
// storage is a SettingsStorage object that can be serialized to various formats

// Load from custom storage
var newCache = new DatabaseConnectionCache();
newCache.Load(storage);

Application Settings Integration

public class AppSettings
{
    private readonly DatabaseConnectionCache _connectionCache = new();
    private readonly string _settingsFile = "appsettings.json";

    public DatabaseConnectionCache Connections => _connectionCache;

    public void Load()
    {
        if (File.Exists(_settingsFile))
        {
            var serializer = new JsonSerializer<SettingsStorage>();
            var storage = serializer.Deserialize(File.ReadAllText(_settingsFile));
            _connectionCache.Load(storage);
        }
    }

    public void Save()
    {
        var storage = new SettingsStorage();
        _connectionCache.Save(storage);

        var serializer = new JsonSerializer<SettingsStorage>();
        File.WriteAllText(_settingsFile, serializer.Serialize(storage));
    }
}

// Usage
var settings = new AppSettings();
settings.Load();

// Add connections
settings.Connections.GetOrAdd("SqlServer", "Server=localhost");

// Save changes
settings.Save();

Provider Registry

Implementing a Provider Registry

using Ecng.Data;
using LinqToDB;

public class CustomDatabaseProviderRegistry : IDatabaseProviderRegistry
{
    public string[] Providers { get; } =
    [
        ProviderName.SqlServer,
        ProviderName.SQLite,
        ProviderName.MySql,
        ProviderName.PostgreSQL,
        ProviderName.Oracle
    ];

    public void Verify(DatabaseConnectionPair connection)
    {
        try
        {
            using var db = connection.CreateConnection();
            using var conn = db.DataProvider.CreateConnection(db.ConnectionString);
            conn.Open();
            Console.WriteLine($"Connection to {connection.Provider} verified successfully");
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException(
                $"Failed to verify connection to {connection.Provider}: {ex.Message}",
                ex
            );
        }
    }
}

Using the Provider Registry

var registry = new CustomDatabaseProviderRegistry();

// Display available providers
Console.WriteLine("Available providers:");
foreach (var provider in registry.Providers)
{
    Console.WriteLine($"  - {provider}");
}

// Verify a connection
var connection = new DatabaseConnectionPair
{
    Provider = ProviderName.SqlServer,
    ConnectionString = "Server=localhost;Database=MyDb;Trusted_Connection=True;"
};

try
{
    registry.Verify(connection);
    Console.WriteLine("Connection is valid!");
}
catch (Exception ex)
{
    Console.WriteLine($"Connection verification failed: {ex.Message}");
}

API Reference

DatabaseConnectionPair

Member	Type	Description
`Provider`	`string`	The database provider type (e.g., "SqlServer", "SQLite", "MySql")
`ConnectionString`	`string`	The connection string for the database
`Title`	`string`	Read-only formatted string: "({Provider}) {ConnectionString}"
`Load(SettingsStorage)`	`void`	Loads the pair from settings storage
`Save(SettingsStorage)`	`void`	Saves the pair to settings storage
`Equals(object)`	`bool`	Compares pairs using case-insensitive comparison
`GetHashCode()`	`int`	Returns case-insensitive hash code

DatabaseConnectionCache

Member	Type	Description
`Connections`	`IEnumerable<DatabaseConnectionPair>`	Gets all cached connection pairs
`GetOrAdd(string, string)`	`DatabaseConnectionPair`	Gets existing or adds new connection pair
`DeleteConnection(DatabaseConnectionPair)`	`bool`	Removes connection from cache
`Load(SettingsStorage)`	`void`	Loads connections from storage
`Save(SettingsStorage)`	`void`	Saves connections to storage
`ConnectionCreated`	`event Action<DatabaseConnectionPair>`	Raised when a new connection is added
`ConnectionDeleted`	`event Action<DatabaseConnectionPair>`	Raised when a connection is removed
`Updated`	`event Action`	Raised when the cache is modified

IDatabaseProviderRegistry

Member	Type	Description
`Providers`	`string[]`	Gets the list of available database providers
`Verify(DatabaseConnectionPair)`	`void`	Verifies a connection by attempting to open it

Extension Methods (Linq2Db Integration)

Method	Return Type	Description
`CreateConnection(this DatabaseConnectionPair)`	`DataConnection`	Creates a Linq2Db DataConnection from the pair

Advanced Scenarios

Pooling Multiple Database Connections

public class MultiDatabaseService
{
    private readonly DatabaseConnectionCache _cache;

    public MultiDatabaseService()
    {
        _cache = new DatabaseConnectionCache();

        // Set up connections for different databases
        _cache.GetOrAdd(ProviderName.SqlServer, "Server=localhost;Database=MainDb;...");
        _cache.GetOrAdd(ProviderName.SQLite, "Data Source=cache.sqlite;...");
        _cache.GetOrAdd(ProviderName.MySql, "Server=localhost;Database=Analytics;...");
    }

    public void ExecuteOnAll(Action<DatabaseConnectionPair> action)
    {
        foreach (var connection in _cache.Connections)
        {
            action(connection);
        }
    }

    public T ExecuteQuery<T>(string provider, Func<DataConnection, T> query)
    {
        var pair = _cache.Connections.FirstOrDefault(c =>
            c.Provider.EqualsIgnoreCase(provider));

        if (pair == null)
            throw new InvalidOperationException($"Provider {provider} not found");

        using var connection = pair.CreateConnection();
        return query(connection);
    }
}

// Usage
var service = new MultiDatabaseService();

var sqlServerUsers = service.ExecuteQuery(ProviderName.SqlServer, db =>
    db.GetTable<User>().ToList()
);

service.ExecuteOnAll(pair =>
{
    using var conn = pair.CreateConnection();
    Console.WriteLine($"Testing {pair.Provider}...");
    conn.Execute("SELECT 1");
});

Connection Testing and Health Checks

public class ConnectionHealthChecker
{
    private readonly DatabaseConnectionCache _cache;
    private readonly IDatabaseProviderRegistry _registry;

    public ConnectionHealthChecker(
        DatabaseConnectionCache cache,
        IDatabaseProviderRegistry registry)
    {
        _cache = cache;
        _registry = registry;
    }

    public Dictionary<DatabaseConnectionPair, bool> CheckAllConnections()
    {
        var results = new Dictionary<DatabaseConnectionPair, bool>();

        foreach (var connection in _cache.Connections)
        {
            try
            {
                _registry.Verify(connection);
                results[connection] = true;
                Console.WriteLine($"✓ {connection.Title}");
            }
            catch (Exception ex)
            {
                results[connection] = false;
                Console.WriteLine($"✗ {connection.Title}: {ex.Message}");
            }
        }

        return results;
    }

    public async Task<bool> MonitorConnectionAsync(
        DatabaseConnectionPair connection,
        TimeSpan interval,
        CancellationToken cancellationToken)
    {
        while (!cancellationToken.IsCancellationRequested)
        {
            try
            {
                _registry.Verify(connection);
                await Task.Delay(interval, cancellationToken);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Connection lost: {ex.Message}");
                return false;
            }
        }

        return true;
    }
}

Dynamic Configuration Management

public class DynamicConnectionManager
{
    private readonly DatabaseConnectionCache _cache;
    private readonly IConfiguration _configuration;

    public DynamicConnectionManager(IConfiguration configuration)
    {
        _configuration = configuration;
        _cache = new DatabaseConnectionCache();
        LoadFromConfiguration();
    }

    private void LoadFromConfiguration()
    {
        var connections = _configuration
            .GetSection("DatabaseConnections")
            .GetChildren();

        foreach (var connConfig in connections)
        {
            var provider = connConfig["Provider"];
            var connectionString = connConfig["ConnectionString"];

            if (!string.IsNullOrEmpty(provider) &&
                !string.IsNullOrEmpty(connectionString))
            {
                _cache.GetOrAdd(provider, connectionString);
            }
        }
    }

    public void ReloadConfiguration()
    {
        // Clear and reload
        foreach (var conn in _cache.Connections.ToList())
        {
            _cache.DeleteConnection(conn);
        }

        LoadFromConfiguration();
    }

    public DatabaseConnectionPair GetConnection(string name)
    {
        return _cache.Connections.FirstOrDefault(c =>
            c.Title.Contains(name, StringComparison.OrdinalIgnoreCase)
        );
    }
}

// appsettings.json example:
// {
//   "DatabaseConnections": [
//     {
//       "Provider": "SqlServer",
//       "ConnectionString": "Server=localhost;Database=MyDb;..."
//     },
//     {
//       "Provider": "SQLite",
//       "ConnectionString": "Data Source=mydb.sqlite"
//     }
//   ]
// }

Thread-Safe Operations

public class ConcurrentConnectionManager
{
    private readonly DatabaseConnectionCache _cache;
    private readonly object _lock = new();

    public ConcurrentConnectionManager()
    {
        _cache = new DatabaseConnectionCache();
    }

    public DatabaseConnectionPair SafeGetOrAdd(string provider, string connectionString)
    {
        lock (_lock)
        {
            return _cache.GetOrAdd(provider, connectionString);
        }
    }

    public async Task<List<TResult>> ExecuteInParallel<TResult>(
        Func<DatabaseConnectionPair, TResult> operation)
    {
        var tasks = _cache.Connections
            .Select(conn => Task.Run(() => operation(conn)))
            .ToList();

        return (await Task.WhenAll(tasks)).ToList();
    }
}

// Usage
var manager = new ConcurrentConnectionManager();

// Execute queries in parallel across all databases
var results = await manager.ExecuteInParallel(pair =>
{
    using var conn = pair.CreateConnection();
    return conn.GetTable<User>().Count();
});

Console.WriteLine($"Total users across all databases: {results.Sum()}");

Best Practices

Always dispose connections: Use using statements when creating connections
Validate connection strings: Verify connections before using them in production
Use caching: Leverage DatabaseConnectionCache to avoid duplicate connection definitions
Handle events: Subscribe to cache events for logging and monitoring
Persist configurations: Save connection cache to disk for application state management
Thread safety: The cache is thread-safe, but always consider synchronization in multi-threaded scenarios
Security: Never hard-code connection strings; use configuration files or secure storage
Provider names: Use constants from LinqToDB.ProviderName for consistency

License

Part of the StockSharp project. See the main repository for license information.

Related Projects

Ecng.ComponentModel - Base component model and notification support
Ecng.Serialization - Serialization infrastructure used by this library
Ecng.Data.Linq2db - Linq2Db integration extensions

StockSharp/Ecng.Datav1.0.423

Get Started

Readme

Ecng.Data

Table of Contents

Overview

Installation

Key Features

Core Components

DatabaseConnectionPair

DatabaseConnectionCache

IDatabaseProviderRegistry

Usage Examples

Basic Connection Management

Creating a Connection Pair

Using with Linq2Db

Connection Caching

Basic Cache Operations

Automatic Deduplication

Event Handling

Monitoring Connection Lifecycle

Building a Connection Manager UI

Persistence

Saving and Loading Connections

Custom Persistence Storage

Application Settings Integration

Provider Registry

Implementing a Provider Registry

Using the Provider Registry

API Reference

DatabaseConnectionPair

DatabaseConnectionCache

IDatabaseProviderRegistry

Extension Methods (Linq2Db Integration)

Advanced Scenarios

Pooling Multiple Database Connections

Connection Testing and Health Checks

Dynamic Configuration Management

Thread-Safe Operations

Best Practices

License

Related Projects

StockSharp/Ecng.Datav1.0.423

Get Started

Readme

Ecng.Data

Table of Contents

Overview

Installation

Key Features

Core Components

DatabaseConnectionPair

DatabaseConnectionCache

IDatabaseProviderRegistry

Usage Examples

Basic Connection Management

Creating a Connection Pair

Using with Linq2Db

Connection Caching

Basic Cache Operations

Automatic Deduplication

Event Handling

Monitoring Connection Lifecycle

Building a Connection Manager UI

Persistence

Saving and Loading Connections

Custom Persistence Storage

Application Settings Integration

Provider Registry

Implementing a Provider Registry

Using the Provider Registry

API Reference

DatabaseConnectionPair

DatabaseConnectionCache

IDatabaseProviderRegistry

Extension Methods (Linq2Db Integration)

Advanced Scenarios

Pooling Multiple Database Connections

Connection Testing and Health Checks

Dynamic Configuration Management