c# - 如何将完整的 Sqlite 连接字符串传递给 DbContext

Question

我试图将完整的连接字符串作为参数传递给 DbContext 构造函数，但出现此错误:

Unable to complete operation. The supplied SqlConnection does not specify an initial catalog or AttachDBFileName.

这是我尝试过的:

public DatabaseContext() :base(@"Data Source=|DataDirectory|ComponentDatabase.sqlite") {}

---

问题除了连接字符串之外别无其他，因为我能够使用 App.config 中的连接字符串连接我的数据库，如下所示:

App.config

<?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" />
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
  </configSections>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
  </startup>
  <entityFramework>
    <providers>
      <provider invariantName="System.Data.SQLite" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
    </providers>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
  <connectionStrings>
    <!-- use AppDomain.SetData to set the DataDirectory -->
    <add name="MapDbConnectionStr" connectionString="Data Source=|DataDirectory|ComponentDatabase.sqlite" providerName="System.Data.SQLite" />
  </connectionStrings>
  <system.data>
    <DbProviderFactories>
      <remove invariant="System.Data.SQLite.EF6" />
      <add name="SQLite Data Provider (Entity Framework 6)" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite (Entity Framework 6)" type="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6" />
    <remove invariant="System.Data.SQLite" /><add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".NET Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" /></DbProviderFactories>
  </system.data>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Data.SQLite" publicKeyToken="db937bc2d44ff139" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-1.0.105.2" newVersion="1.0.105.2" />
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="System.Data.SQLite.EF6" publicKeyToken="db937bc2d44ff139" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-1.0.105.2" newVersion="1.0.105.2" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

数据库上下文

public DatabaseContext() :base("MapDbConnectionStr") {}

附言我知道 App.config 有很多不必要的行，是的。

Answer 1

据我所知，您尝试连接的数据库类型没有连接工厂。

您可以编写自己的连接工厂:

public class MySqlLiteConnectionFactory : IDbConnectionFactory
{
    public DbConnection CreateConnection(string connectionString)
    {
        return new SQLiteConnection(connectionString);
    }
}

现在在 app.config 中找到 defaulConnectionfactory 条目并替换指定类型的行。目前这将是这样的:

<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">

改成这样:

<defaultConnectionFactory type="MyNamespace.MySQLiteConnectionFactory, MyAssemblyHere" />

您现在应该能够正确使用 Context ctor (string connectionString)。

还有一个方法是在不依赖应用程序设置的情况下执行此操作，EF 6 及更高版本支持基于代码的配置。

所以你可以用看起来有点像这样的配置来做一些事情:

DbConfiguration.Loaded += (_, a) => 
   { 
       a.ReplaceService<DbProviderServices>((s, k) => new MyProviderServices(s)); 
       a.ReplaceService<IDbConnectionFactory>((s, k) => new MyConnectionFactory(s)); 
   };

详细信息已记录在案 here at microsoft :