how to obtain an attribute value using attribute name as a string, like object["foo"]

Question

Can an object in C# return the value of one of its attributes if the name of the desired attribute is provided as a string at runtime?

myObject["price"]

Let's say we have this object:

public class Widget
{
     public Widget(){}
     public DateTime productionDate {get;set;}
     public decimal price {get;set;}
}

and this SqlCommand parameter definition:

 SqlCommand c = new SqlCommand();
 c.Parameters.Add(new SqlParameter("@price", SqlDbType.SmallMoney,0,"price"));

Elsewhere in the code in a different scope, the user has clicked on a [Save Record] button and now we need to bind the values in a widget object to the parameters of an update command. We have a reference to that SqlCommand in variable command:

foreach (SqlParameter p in command.Parameters)
{     
     // assume `parameter.SourceColumn` matches the widget attribute name

     string attributeName = p.SourceColumn;

     p.Value = widget[attributeName]      // ??
  }

I think you mean "property", not attribute which has its own meaning in c#. And yes, you can use Reflection to get a Property value by name. — Crowcoder
– Crowcoder, Commented May 13, 2017 at 12:12
To access a property exactly like you're referring to, you'd need some type of Dictionary<string, object> which lets you obtain a value through the key accessor public TValue this[TKey key] { get; set; } — Mark C.
– Mark C., Commented May 13, 2017 at 12:38

Danny · Accepted Answer · 2017-05-13 12:47:08Z

2

Addition to Crowcoder:

You can use reflection and call Type.GetProperty("nameOfProperty") to get a PropertyInfo on which you can call the GetMethod property.

The GetMethod property returns a MethodInfo on which you can call the Invoke method to retrieve the value of the property.

For instance:

var propertyInfo = myObject.GetType().GetProperty("price");
var getMethod = propertyInfo.GetMethod;
string value = getMethod.Invoke(myObject, null) as string

Edit:

After reading your question again, I realise, I didn't answer your question. You should/could combine my previous answer with an Indexer: https://learn.microsoft.com/en-us/dotnet/articles/csharp/programming-guide/indexers/index

edited May 13, 2017 at 12:47

answered May 13, 2017 at 12:38

Danny

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