C# use string as a class field name

Question

Sorry if the tile is misleading. What i would like to do is to use a string to get the values from a class. What i have:

class foo
{
    public string field1 {get;set;}
    public string field2 {get;set;}
}

public void run()
{
    //Get all fields in class
    List<string> AllRecordFields = new List<string>();
    Type t = typeof(foo);
    foreach (MemberInfo m in t.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
    {
        AllRecordFields.Add(m.Name);
    }

    foo f = new foo();
    foreach(var field in AllRecordFields)
    { 
        //field is a string with the name of the real field in class
        f.field = "foobar";
    }
}

This a really simple example, so the problem is on the line f.field = "foobar"; The field is a string with a name of the real class field what i want to assignt the value to.

Do you want to set the value of foo.field1 or do you want to change the name of foo.field1 to e.g. foo.bar1? — PVitt
– PVitt, Commented Nov 18, 2011 at 8:56
In this example i want to set all the class foo field values to "foobar". — hs2d
– hs2d, Commented Nov 18, 2011 at 8:58
You also have FieldInfo.GetValue not sure as what are you looking out for ? — V4Vendetta
– V4Vendetta, Commented Nov 18, 2011 at 9:01
if you want to set field values of class to "foobar" then it is simple right, what is the problem i didn't get. just make your field public — FosterZ
– FosterZ, Commented Nov 18, 2011 at 9:04

H-Man2 · Accepted Answer · 2011-11-18 09:23:05Z

3

Use PropertyInfo instead of MemberInfo and then SetValue.

public void run()
{
  foo f = new foo();
  Type t = typeof(foo);

  foreach (PropertyInfo info in t.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic))
  {
     info.SetValue(f, "foobar", new object[0]);
  }
}

edited Nov 18, 2011 at 9:23

answered Nov 18, 2011 at 9:01

H-Man2

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1 Comment

Ray Over a year ago

FYI The question was changed, you need PropertyInfo and GetProperties now

MBen · Accepted Answer · 2011-11-18 08:59:04Z

0

First of all, it is better to use Properties instead of fields. Second your fields are private, can't be accessed from outside foo. You need to declare them as public.

answered Nov 18, 2011 at 8:59

MBen

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5 Comments

H-Man2 Over a year ago

Using reflection you can access a private field. Sure it is not a good practice in common, but some applications and libraries like ORM need this kind of access.

MBen Over a year ago

Hi @H-Man2 when do ORM need to access your internal implementation? fields should be hidden, if they need to access your inner core something is wrong.

H-Man2 Over a year ago

No there is nothing wrong, shure it breaks encapsulating. You need this access for generic algorithms, like (de-)serialization (as used in .NET itself).

MBen Over a year ago

Thanks for the explanation, some resources about that?

H-Man2 Over a year ago

I found two possibly interesting links: 1 2

Fischermaen · Accepted Answer · 2011-11-18 09:02:18Z

0

For your example you have to use reflection to access those files. But that is slow and it is not very good style. You better use the class directly (with property setter) or us an interface.

answered Nov 18, 2011 at 9:02

Fischermaen

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Comments

ArekBee · Accepted Answer · 2011-11-18 10:06:31Z

Add method into foo class to change all properties

   class foo
    {
        public string field1 {get;set;}
        public string field2 { get; set; }

        public void SetValueForAllString( string value)
        {
            var vProperties = this.GetType().GetProperties();
            foreach (var vPropertie in vProperties)
            {
                if (vPropertie.CanWrite 
                    && vPropertie.PropertyType.IsPublic 
                    && vPropertie.PropertyType == typeof(String))
                {
                    vPropertie.SetValue(this, value, null);
                }
            }

        }
    }

    foo f = new foo() { field1 = "field1", field2 = "field2" };
                f.SetValueForAllString("foobar");
                var field1Value = f.field1; //"foobar"

             var field2Value = f.field2; //"foobar"

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