Question

So I am writing, strictly for personal learning, an ORM in C#. I am looping through a database, where the column names match the properties of a class. I am then looping through the properties of the class and assigning the corresponding database column values but i am running into issues casting the return value from the database column.

var PropCollection = type.GetProperties();
foreach (PropertyInfo Property in PropCollection)
{
    Property.SetValue(_t, DReader[Property.Name].ToString(),null);
}

I get the expected error:

Object of type ‘System.String’ cannot be converted to type
‘System.Int32’.

Where DReader is just an SQLDataReader returning a column value inside of a loop, say this value is an int, how do I cast it as such??

Property.GetType();

correctly knows the type I need but how do I use that to cast DReader[Property.Name]?

Answer 1

Convert.ChangeType can handle all straight conversions.

You should not use DReader[Property.Name].ToString() in your loop. Remove the ToString().

var PropCollection = type.GetProperties();
foreach (PropertyInfo Property in PropCollection)
{
    var value = DReader[Property.Name];
    if (!Property.GetType().IsAssignableFrom(value.GetType())
        value = Convert.ChangeType(value, Property.GetType());

    Property.SetValue(_t, value, null);
}