c# DynamicObject class dynamic properties from loop

Question

So I've created a class that inherits DynamicObject

public class MyDynamicObject : DynamicObject{
private Dictionary<string, object> Fields = new Dictionary<string, object>();

public override bool TryGetMember(GetMemberBinder binder, out object result)
{
    return Fields.TryGetValue(binder.Name, out result);
}

public override bool TrySetMember(SetMemberBinder binder, object value)
{
    Fields[binder.Name] = value;
    return true;
}
}

And call this class here

public class Program
{
public static void Main()
{
    dynamic person = new MyDynamicObject();
    person.firstname = "Hello";
    Console.WriteLine(person.firstname);
 }
}

Of course this will work. But I need to create properties from a string array like

string[] fields = new string[]{"taxid","newcol","addrs","gender"};
dynamic person = new MyDynamicObject();
foreach(var f in fields)
{
  person.f = "hello";
}

So the output will be person.taxi, person.newcol, person.addrs, person.gender

Is this possible?

Take a look at the built-in ExpandoObject; Essentially you'll have to expose a method for adding fields to the dictionary. — user6144226
– user6144226, Commented Sep 8, 2017 at 11:50
I think your question might be answered at stackoverflow.com/a/4938442/1462295 — BurnsBA
– BurnsBA, Commented Sep 8, 2017 at 11:57
Regarding what the first commenter said, why not just have a dictionary do this? person[f] ="hello" — Kevin Hirst
– Kevin Hirst, Commented Sep 8, 2017 at 12:08
I already did it using ExpandoObject and its working, but my requirement is to create a class that will have a dynamic properties and can be instantiated, I dont know if its possible — etcz0ne
– etcz0ne, Commented Sep 8, 2017 at 12:21

Jon Hanna · Accepted Answer · 2017-09-08 12:52:43Z

1

Expose the Fields dictionary in some way, or (better) a method that allows one to explicitly set a property by name.

Note that ExpandoObject already does this, as it can be cast to IDictionary<string, object> and then you

ExpandoObject eo = new ExpandoObject();
IDictionary<string, object> dict = eo;
dynamic d = eo;
dict["MyProperty"] = 42;
Console.WriteLine(d.MyProperty); // 42

If you can't just use ExpandoObject itself, you can copy its approach.

answered Sep 8, 2017 at 12:52

Jon Hanna

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Comments

etcz0ne · Accepted Answer · 2017-09-12 08:16:08Z

Okay so based on the suggestion of @Jon Hanna, I came up with a solution that fits my requirements. I created a new Add method which accept a name. Below is the updated code I used.

public class DynamicFormData : DynamicObject
{
    private Dictionary<string, object> Fields = new Dictionary<string, object>();

    public int Count { get { return Fields.Keys.Count; } }

    public void Add(string name, string val = null)
    {
        if (!Fields.ContainsKey(name))
        {
            Fields.Add(name, val);
        }
        else
        {
            Fields[name] = val;
        }
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        if (Fields.ContainsKey(binder.Name))
        {
            result = Fields[binder.Name];
            return true;
        }
        return base.TryGetMember(binder, out result); 
    }

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        if (!Fields.ContainsKey(binder.Name))
        {
            Fields.Add(binder.Name, value);
        }
        else
        {
            Fields[binder.Name] = value;
        }
        return true;
    }

    public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)
    {
        if (Fields.ContainsKey(binder.Name) &&
            Fields[binder.Name] is Delegate)
        {
            Delegate del = Fields[binder.Name] as Delegate;
            result = del.DynamicInvoke(args);
            return true;
        }
        return base.TryInvokeMember(binder, args, out result);
    }
}

Then I just call it like this.

string[] fields = new string[]{"taxid","newcol","addrs","gender"};
dynamic formData = new DynamicFormData();

foreach(string field in fields)
{
    formData.Add(field, null);
}

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