Use DBContext with Oracle

Question

I have searched the web and reviewed similar questions on Stack Overflow but I can not figure how to use the Oracle Managed Data Provider with a DbContext from a C# .Net 4.6 Console Application.

This works for Sql Express

class SqlDBContext1 : DbContext
{
    public SqlDBContext1() : base("SqlExpressDB")
    {
        using (var ctx = this)
        { var query = from c_codes in ctx.CountryCodes select c_codes; }
    }
    public DbSet<CountryCode> CountryCodes { get; set; }
}

And this works to connect to a remote Sql Server, using a connection string

class SqlDBContext2 : DbContext
{
    public SqlDBContext2() : base(SqlServerString())
    {
        using (var ctx = this)
        { var query = from c_codes in ctx.CountryCodes select c_codes; }
    }
    public DbSet<CountryCode> CountryCodes { get; set; }
    private static string SqlServerString()
    {
        return @"Data Source=192.168.0.1;" +
                "Initial Catalog=SqlDB1; " +
                "Persist Security Info=True; " +
                "User ID=USER1; " +
                "Password=PASS1";
    }
}

I can connect to Oracle from Visual Studio 2017 and I have verified the connection string using a standard OracleConnection, it opens and closes, no problem.

With this in the APP.CONFIG

  <oracle.manageddataaccess.client>
    <version number="*">
      <dataSources>
        <dataSource alias="ORCL1" descriptor="(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.0.1)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=ORCL1))) "/>
      </dataSources>
    </version>
  </oracle.manageddataaccess.client>
  <connectionStrings>
    <add name="ORCL1DB" providerName="Oracle.ManagedDataAccess.Client" connectionString="User Id=USER1;Password=PASS1;Data Source=ORCL1"/>
  </connectionStrings>

Can I use something like this? If so, what goes into the DbContext's base contructor?

class OraDBContext : DbContext
{
    public OraDBContext() : base("What goes here")
    {
        using (var ctx = this)
        { var query = from c_codes in ctx.CountryCodes select c_codes; }
    }
    public DbSet<CountryCode> CountryCodes { get; set; }
}

None of the examples I have found on Stack Overflow work, various errors of which 'Type Initializor threw an exception' being the most popular.

vscoder · Accepted Answer · 2019-02-28 22:51:06Z

Not sure what I did different but now it works, for future generations.

In APP.CONFIG I have this

  <oracle.manageddataaccess.client>
    <version number="*">
      <dataSources>
        <dataSource alias="ORCL1" descriptor="(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.0.1)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=ORCL1))) "/>
      </dataSources>
    </version>
  </oracle.manageddataaccess.client>
  <connectionStrings>
    <add name="ORCL1DB" providerName="Oracle.ManagedDataAccess.Client" connectionString="User Id=USER1;Password=PASS1;Data Source=ORCL1"/>
  </connectionStrings>

My class looks like this

class OraDBContext : DbContext
{
    public OraDBContext() : base(ORCL1COnnection(), true)
    {
        using (var ctx = this)
        {
            var query = from c_codes in ctx.CountryCodes select c_codes;
        }
    }

    public DbSet<CountryCode> CountryCodes { get; set; }

    public static OracleConnection ORCL1COnnection()
    {
        var c1 = ConfigurationManager.ConnectionStrings["ORCL1DB"];
        OracleConnection ora_con = new OracleConnection(c1.ConnectionString);
        return ora_con;
    }
}

This was failing before but is working now.

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