CODEWITHSUNDEEP
c#generics
Ron
Ron

Reputation: 2503

GetProperty in Generic class returns null

In a project I'm working has a class defined like this:

class DataImport<T> : DataBaseClass where T : IDataEntity, new()
{
}

The IDataEntity has fields like this:

string tableName { get; }
string Id { get; }
int TypeId { get;  }

In a class that implements this interface there is this:

string IDataEntity.Id { get { return myobject_id.ToString(); } }        
int IDataEntity.TypeId { get { return 10; } }
string IDataEntity.tableName { get { return "tblObjects"; } }

For example.

In the DataImport object I would like to do this:

string x = (T).tableName;

etc. But of course I can't do that. I've tried declaring them as public but it's not allowed.

How would I access the tableName, Id and TypeId properties? I've looked at typeof(T).GetProperties() but they are null; in GetFields() also.

Upvotes: 0

Views: 467

Answers (1)

Ren&#233; Vogt
Ren&#233; Vogt

Reputation: 43876

There are two issues:

  1. You need an instance of T to access the non-static property tableName, in your example you call (T).tableName on the type instead of an instance.
  2. Since your class implements the interface explicitly (string IDataEntity.tableName) you will need to cast the instance of T into an IDataEntity explicitly.

So your DataImport implementation should look like this:

class DataImport<T> : DataBaseClass where T : IDataEntity, new()
{
    public void WriteTableName(T arg)
    {
        string x = ((IDataEntity)arg).tableName;
        Console.WriteLine(x);
    }
}

Upvotes: 4

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