如何在 Jonathan Oliver 的 EventStore 中获取使用连接字符串配置的 SqlPersistence 实例？答案

【问题标题】：How to get SqlPersistence instance configured with connection string in Jonathan Oliver's EventStore?如何在 Jonathan Oliver 的 EventStore 中获取使用连接字符串配置的 SqlPersistence 实例？
【发布时间】：2020-10-27 18:22:30
【问题描述】：

下面的代码将为命名连接创建事件存储。

var es = Wireup.Init()                                
    .UsingSqlPersistence("DB")
    .Build();

我需要类似的东西：

var es = Wireup.Init()                                
    .UsingSqlPersistence("Data Source=TEST;Initial Catalog=App")
    .Build();

我发现最简单的方法是创建自定义 IConnectionFactory，但这看起来不正确。有什么建议吗？

【问题讨论】：

标签： c# event-sourcing neventstore

【解决方案1】：

我没有找到使用任何内置类的方法，但是您提到的接口或多或少易于使用。

使用 joliver 的代码，我实现了一个连接字符串工厂，如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Common;
using System.Configuration;
using System.Data;
using EventStore.Persistence.SqlPersistence;
using EventStore.Persistence;

namespace Project.Factories
{
    public class ConnectionStringConnectionFactory : IConnectionFactory
    {
        private static readonly IDictionary<string, DbProviderFactory> CachedFactories =
            new Dictionary<string, DbProviderFactory>();

        private string m_connectionString;
        private string m_providerName;

        private string m_replicaConnectionString;
        private string m_replicaProviderName;

        public ConnectionStringConnectionFactory(string connectionString, string providerName)
            : this(connectionString, providerName, connectionString, providerName)
        {

        }

        public ConnectionStringConnectionFactory(
            string connectionString,
            string providerName,
            string replicaConnectionString,
            string replicaProviderName)
        {
            m_connectionString = connectionString;
            m_providerName = providerName;
            m_replicaConnectionString = replicaConnectionString;
            m_replicaProviderName = replicaProviderName;
        }


        public virtual IDbConnection OpenMaster(Guid streamId)
        {
            return this.Open(streamId, m_connectionString, m_providerName);
        }

        public virtual IDbConnection OpenReplica(Guid streamId)
        {
            return this.Open(streamId, m_replicaConnectionString, m_replicaProviderName);
        }

        protected virtual IDbConnection Open(Guid streamId, string connectionString, string providerName)
        {
            return new ConnectionScope(connectionString, () => this.Open(connectionString, providerName));
        }

        protected virtual IDbConnection Open(string connectionString, string providerName)
        {
            var factory = this.GetFactory(providerName);
            var connection = factory.CreateConnection();
            if (connection == null)
                throw new ConfigurationErrorsException("Invalid provider name");

            connection.ConnectionString = connectionString;

            try
            {
                connection.Open();
            }
            catch (Exception e)
            {
                throw new StorageUnavailableException(e.Message, e);
            }

            return connection;
        }

        protected virtual DbProviderFactory GetFactory(string providerName)
        {
            lock (CachedFactories)
            {
                DbProviderFactory factory;
                if (CachedFactories.TryGetValue(providerName, out factory))
                    return factory;

                factory = DbProviderFactories.GetFactory(providerName);
                return CachedFactories[providerName] = factory;
            }
        }

        public ConnectionStringSettings Settings
        {
            get { return new ConnectionStringSettings("Default", m_connectionString, m_providerName); }
        }
    }
}

要使用它，只需传入一个工厂：

var fac = new ConnectionStringConnectionFactory(
          "Your Connection String",
          "System.Data.SqlClient");

Wireup.Init().UsingSqlPersistence(fac)

如果您愿意，可以将其包装在扩展方法中：

Wireup.Init().UsingSqlPersistenceWithConnectionString("")

【讨论】：

【解决方案2】：

创建了一个拉取请求以支持带有连接字符串的配置。

https://github.com/NEventStore/NEventStore/pull/358

如果不接受，您仍然可以在自己的项目中使用该代码启用连接字符串配置，只需几行代码。

更新： 拉取请求被接受，并且从 NEventstore 的 5.1 版开始可用。现在可以在 nuget 上使用。

【讨论】：