Using method parameter as reference in object

Question

I am returning a list of codes called AllCodes from a SQL database. Basic schema like:

id | countrycode | refprint | refscan | reffax 
1 . US . 123 . 234 . 345

I have a method which should needs to return a a value based on a matching countrycode and whatever column I need from that result.

Here is the method (not working offcourse) but not sure how to achieve this kind of thing with c#

  private string GetServiceCode(string cc, string name)
    {
        var code = AllCodes.Where(x => x.CountryCode == cc).FirstOrDefault();
        if (code != null)
        {
            // I want to return whatever {name} is, not code.name
            // so if name = "refprint" I want to return code.refprint
            return code.{name};
        }
    }

  // Example:
  GetServiceCode("US","refprint"); // Would return 123

you could look at Dynamic Linq - then it would be .Select(name) — user3559349
– user3559349, Commented Sep 12, 2016 at 12:58

Graham · Accepted Answer · 2017-09-29 17:24:19Z

2

You could achieve this with reflection:

if (code != null)
{
    PropertyInfo pi = code.GetType().GetProperty(name);
    if (pi == null) return string.Empty;
    object v = pi.GetValue(code);
    if (v == null) return string.Emtpy;
    return v.ToString();
}

With GetProperty() you can get a PropertyInfo for the property named name. Then you can use GetValue() to get the value of the property for a specific instance (code in your case).

In C#6 you could shorten the code to

return code.GetType().GetProperty(name)?.GetValue(code)?.ToString() ?? string.Empty;

edited Sep 29, 2017 at 17:24

Graham

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answered Sep 12, 2016 at 12:58

René Vogt

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Comments

Neil · Accepted Answer · 2016-09-12 13:07:20Z

0

How about using a lambda:

private string GetServiceCode<T>(string cc, Action<T> action)
{
    var code = AllCodes.Where(x => x.CountryCode == cc).FirstOrDefault();
    if (code != null)
    {
        return action(code);
    }
}

// Example:
GetServiceCode("US",(code)=> Console.WriteLine(code.refprint) );

answered Sep 12, 2016 at 13:07

Neil

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