如何在配置文件注册Firebird ADO.NET Provider解决EF6连接报错

这个问题我之前部署Firebird嵌入式应用时也踩过坑——未安装Firebird Net Provider的机器上，系统没法找到FirebirdSql.Data.FirebirdClient这个ADO.NET Provider的注册信息，所以才会抛出那个错误。要解决这个问题，你需要在app.config里显式注册该Provider，同时确保依赖的程序集随应用一起发布。

具体修改步骤 #

1. 添加<system.data>节点注册Provider #

在你的configuration根节点下，添加一个system.data节点，里面通过DbProviderFactories注册Firebird的ADO.NET Provider，告诉.NET框架这个Provider对应的程序集位置和版本信息：

<system.data>
  <DbProviderFactories>
    <remove invariant="FirebirdSql.Data.FirebirdClient" />
    <add 
      name="FirebirdClient Data Provider" 
      invariant="FirebirdSql.Data.FirebirdClient" 
      description=".NET Framework Data Provider for Firebird" 
      type="FirebirdSql.Data.FirebirdClient.FbProviderFactory, FirebirdSql.Data.FirebirdClient, Version=6.0.0.0, Culture=neutral, PublicKeyToken=3750abcc3150b00c" />
  </DbProviderFactories>
</system.data>

注意：这里的Version要和你实际使用的FirebirdSql.Data.FirebirdClient.dll版本一致，PublicKeyToken是固定的（3750abcc3150b00c），如果版本不对可能会导致加载失败。

2. 确保依赖程序集随应用发布 #

你需要把以下几个dll文件和你的应用程序exe放在同一目录下（未安装Provider的机器没有这些文件）：

• FirebirdSql.Data.FirebirdClient.dll
• EntityFramework.Firebird.dll
• fbclient.dll（就是你连接字符串里指定的嵌入式客户端库）

修改后的完整app.config示例 #

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <section name="ScheduleWorkbench.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
    </sectionGroup>
  </configSections>
  
  <!-- 新增的Provider注册节点 -->
  <system.data>
    <DbProviderFactories>
      <remove invariant="FirebirdSql.Data.FirebirdClient" />
      <add 
        name="FirebirdClient Data Provider" 
        invariant="FirebirdSql.Data.FirebirdClient" 
        description=".NET Framework Data Provider for Firebird" 
        type="FirebirdSql.Data.FirebirdClient.FbProviderFactory, FirebirdSql.Data.FirebirdClient, Version=6.0.0.0, Culture=neutral, PublicKeyToken=3750abcc3150b00c" />
    </DbProviderFactories>
  </system.data>

  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
  </startup>
  <entityFramework>
    <defaultConnectionFactory type="FirebirdSql.Data.EntityFramework6.FbConnectionFactory, EntityFramework.Firebird" />
    <providers>
      <provider invariantName="FirebirdSql.Data.FirebirdClient" type="FirebirdSql.Data.EntityFramework6.FbProviderServices, EntityFramework.Firebird" />
    </providers>
  </entityFramework>
  <connectionStrings>
    <add name="DbModel" connectionString="character set=UTF8;data source=localhost;initial catalog=H:\Projects\ScheduleWorkbench\ScheduleWorkbench\Firebird\SCHEDULE.FDB;user id=SYSDBA;password=masterkey;role=SYSDBA;server type=1;client library=H:\Projects\ScheduleWorkbench\ScheduleWorkbench\Firebird\fbclient.dll" providerName="FirebirdSql.Data.FirebirdClient" />
  </connectionStrings>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="Syncfusion.Shared.Wpf" publicKeyToken="3d67ed1f87d44c89" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-15.2451.0.40" newVersion="15.2451.0.40" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

原理说明 #

正常安装Firebird Net Provider时，它会在系统的machine.config文件中注册FirebirdSql.Data.FirebirdClient这个Provider，这样.NET框架就能找到对应的程序集。但在未安装Provider的机器上，machine.config里没有这个注册信息，所以必须在应用自己的app.config里手动添加，让.NET知道去哪里加载该Provider的程序集。

内容的提问来源于stack exchange，提问作者Nineor