Type switching on string type

Question

I have a class that parses stringified data into native data types (properties on itself). It iterates through the class properties and uses a switch statement that matches on the property type:

using System.Reflection;

…

class DataParser
{
    public int i { get; set; }
    public bool b { get; set; }
    public string s { get; set; }
    public DateTime d { get; set; }
    public Decimal e { get; set; }

    public DataParser()
    {
        PropertyInfo[] properties = this.GetType().GetProperties();
        foreach (PropertyInfo property in properties)
        {
            object currentValue = property.GetValue(this);
            switch (currentValue)
            {
                case Int32 _:
                    …
                    break;
                case DateTime _:
                    …
                    break;
                case Decimal _:
                    …
                    break;
                case Boolean _:
                    …
                    break;
                case string _:
                    …
                    break;
                default:
                    throw new Exception($"Could not find type for {property.PropertyType}");
            }
        }
    }
}

Type matching works for all types except string, which throws with:

Exception: Could not find type for System.String

Perhaps it's not matching because string is a reference type? I've substituted the string case for String and System.String, same result.

UPDATE

As some folks suggested, the value of the string property was null. Setting a default value

public string s { get; set; } = "";

caused it to match.

I strongly suspect it's because the value is null. Null values don't match type patterns. — Jon Skeet, Nov 07 '18 at 11:26
You probably ought to switch on `property.PropertyType`, not the concrete type of the value (which, as Jon points out, may not exist). — Jeroen Mostert, Nov 07 '18 at 11:29
@Romain No, OP isn’t switching on a *type*, they’re switching on a *value* using C#’s new pattern matching syntax. — Konrad Rudolph, Nov 07 '18 at 11:30
You can also use the [TypeCode](https://learn.microsoft.com/en-us/dotnet/api/system.typecode?view=netframework-4.7.2) enum as `case TypeCode.String:` — ikerbera, Nov 07 '18 at 11:30
your `property.GetValue(this)` returns `null`. `null` is **not** a string. — vasily.sib, Nov 07 '18 at 11:47
https://stackoverflow.com/questions/43080505/c-sharp-7-0-switch-on-system-type — Hary, Nov 07 '18 at 12:01

Type switching on string type

0 Answers0