写入数据库时出现 NLog 异常
NLog exception when writing to a database
我将 NLog 4.2.3 配置为使用以下配置写入数据库和文本文件：
<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" autoReload="true" internalLogLevel="Error" internalLogFile="C:/tmp/NLog.txt">
<targets>
<target name="database" xsi:type="Database" dbProvider="Npgsql.NpgsqlFactory,Npgsql,Version=2.0.12.00,Culture=neutral,PublicKeyToken=5d8b90d52f46fda7" connectionString="Server=xxx.xxx.xxx.xxx;Port=5432;User Id=userid;Password=password;Database=testdb;">
<commandText>INSERT INTO invoice_log (message, level, logger) VALUES (@msg, @level, @logger)</commandText>
<parameter name="@msg" layout="${message}" />
<parameter name="@level" layout="${level}" />
<parameter name="@logger" layout="${logger}" />
</target>
<target name="log" xsi:type="File" layout="${longdate} | ${logger} | ${level:uppercase=true}: ${message}" fileName="${basedir}/Logs.txt" keepFileOpen="false" encoding="iso-8859-2" />
</targets>
<rules>
<logger name="*" minlevel="Trace" writeTo="database" />
<logger name="*" minlevel="Trace" writeTo="log" />
</rules>
</nlog>
我正在尝试记录一条简单的 Info 消息。它正确地记录到文本文件，但它对数据库失败，我在 NLog 内部日志文件中收到以下错误：
Error Error when writing to database System.MissingMethodException: No parameterless constructor defined for this object.
at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
at System.Activator.CreateInstance(Type type, Boolean nonPublic)
at System.Activator.CreateInstance(Type type)
at NLog.Targets.DatabaseTarget.OpenConnection(String connectionString)
at NLog.Targets.DatabaseTarget.EnsureConnectionOpen(String connectionString)
at NLog.Targets.DatabaseTarget.WriteEventToDatabase(LogEventInfo logEvent)
at NLog.Targets.DatabaseTarget.Write(LogEventInfo logEvent)
我查看了其他类似问题 (NLog is not writing to database table, NLog to PostgreSQL connection) 的配置，但我看不出我缺少什么？
根据 nlog docs，dbProvider 是在配置文件中注册的工厂的不变名称，或者是实现 IDbConnection 的类型的完全限定名称。 Npgsql.NpgsqlConnection 实现了所需的接口并具有无参数构造函数。 NpgsqlFactory 没有而且它没有无参数的构造函数（错误的原因）。
我将 NLog 4.2.3 配置为使用以下配置写入数据库和文本文件：
<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" autoReload="true" internalLogLevel="Error" internalLogFile="C:/tmp/NLog.txt">
<targets>
<target name="database" xsi:type="Database" dbProvider="Npgsql.NpgsqlFactory,Npgsql,Version=2.0.12.00,Culture=neutral,PublicKeyToken=5d8b90d52f46fda7" connectionString="Server=xxx.xxx.xxx.xxx;Port=5432;User Id=userid;Password=password;Database=testdb;">
<commandText>INSERT INTO invoice_log (message, level, logger) VALUES (@msg, @level, @logger)</commandText>
<parameter name="@msg" layout="${message}" />
<parameter name="@level" layout="${level}" />
<parameter name="@logger" layout="${logger}" />
</target>
<target name="log" xsi:type="File" layout="${longdate} | ${logger} | ${level:uppercase=true}: ${message}" fileName="${basedir}/Logs.txt" keepFileOpen="false" encoding="iso-8859-2" />
</targets>
<rules>
<logger name="*" minlevel="Trace" writeTo="database" />
<logger name="*" minlevel="Trace" writeTo="log" />
</rules>
</nlog>
我正在尝试记录一条简单的 Info 消息。它正确地记录到文本文件，但它对数据库失败，我在 NLog 内部日志文件中收到以下错误：
Error Error when writing to database System.MissingMethodException: No parameterless constructor defined for this object.
at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
at System.Activator.CreateInstance(Type type, Boolean nonPublic)
at System.Activator.CreateInstance(Type type)
at NLog.Targets.DatabaseTarget.OpenConnection(String connectionString)
at NLog.Targets.DatabaseTarget.EnsureConnectionOpen(String connectionString)
at NLog.Targets.DatabaseTarget.WriteEventToDatabase(LogEventInfo logEvent)
at NLog.Targets.DatabaseTarget.Write(LogEventInfo logEvent)
我查看了其他类似问题 (NLog is not writing to database table, NLog to PostgreSQL connection) 的配置，但我看不出我缺少什么？
根据 nlog docs，dbProvider 是在配置文件中注册的工厂的不变名称，或者是实现 IDbConnection 的类型的完全限定名称。 Npgsql.NpgsqlConnection 实现了所需的接口并具有无参数构造函数。 NpgsqlFactory 没有而且它没有无参数的构造函数（错误的原因）。