xamarin forms ... cannot get parameter value from SqlCommand ... error "MarshalByRefObject" claims it is defined in 'mscorlib' .. could not be found

Question

I have a xamarin.forms project. In the PCL I have a class with these 3 lines of code ....

1) SqlCommand cmd = new SqlCommand(); .... (Note: this line of code works)

2) cmd.Parameters.Add(new SqlParameter("@UserID", SqlDbType.Char, 5)).Direction = ParameterDirection.Input; .... (Note: this line of code works)

3) var userid = cmd.Parameters["@UserID"].Value; .... (Note: this line of code DOES NOT work)

I am receiving this message ...

"Reference by type "MarshalByRefObject" claims it is defined in 'mscorlib', but could not be found

these 3 lines of code work in the Android specific project but not in the PCL class

I can ADD the parameters to the SqlCommand in the PCL class but CANNOT retrieve a value

thanks in advance for your help

Answer 1

The full namespace = System.Data.SqlClient.SqlCommand .... i referenced the System.Data.dll in ... C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\MonoAndroid\v1.0

The DLL you referenced is for Mono.Android project only, not for a PCL project. It can not be used in a PCL project. For explaination, please refer to this case.

If you want to use Native Android SQLite in PCL, please use Dependency Service:

1. In your PCL Project. Create an interface(ISQLDb) for your Dependency Service and use the Service with DependencyService.Get<ISQLDb>():

   public interface ISQLDb
   {
       void InitCmd();
   }
   
   private void btnClick_Clicked(object sender, EventArgs e)
   {
       //use the service any where in your PCL project
       ISQLDb db=DependencyService.Get<ISQLDb>();
       db.InitCmd();
   }
   

2. Create a class for Service Implementation in Mono.Android project and register it as Dependency Service:

   //register the Dependency Service
   [assembly:Xamarin.Forms.Dependency(typeof(SQLDbImpl))]
   namespace SQLCommandDemo.Droid
   {
       //implements the ISQLDb Interface
       public class SQLDbImpl : ISQLDb
       {
           public void InitCmd()
           {
               SqlCommand cmd = new SqlCommand();
               cmd.Parameters.Add(new SqlParameter("@UserID", SqlDbType.Char, 5)).Direction = ParameterDirection.Input;
               var userid = cmd.Parameters["@UserID"].Value;
           }
       }
   }