[c#] Get value of c# dynamic property via string

I'd like to access the value of a dynamic c# property with a string:

dynamic d = new { value1 = "some", value2 = "random", value3 = "value" };

How can I get the value of d.value2 ("random") if I only have "value2" as a string? In javascript, I could do d["value2"] to access the value ("random"), but I'm not sure how to do this with c# and reflection. The closest I've come is this:

d.GetType().GetProperty("value2") ... but I don't know how to get the actual value from that.

As always, thanks for your help!

To get properties from dynamic doc when .GetType() returns null, try this:

var keyValuePairs = ((System.Collections.Generic.IDictionary<string, object>)doc);
var val = keyValuePairs["propertyName"].ToObject<YourModel>;

Similar to the accepted answer, you can also try GetField instead of GetProperty.

d.GetType().GetField("value2").GetValue(d);

Depending on how the actual Type was implemented, this may work when GetProperty() doesn't and can even be faster.

d.GetType().GetProperty("value2")

returns a PropertyInfo object.

So then do

propertyInfo.GetValue(d)

The GetProperty/GetValue does not work for Json data, it always generate a null exception, however, you may try this approach:

Serialize your object using JsonConvert:

var z = Newtonsoft.Json.JsonConvert.DeserializeObject(Convert.ToString(request));

Then access it directly casting it back to string:

var pn = (string)z["DynamicFieldName"];

It may work straight applying the Convert.ToString(request)["DynamicFieldName"], however I haven't tested.

public static object GetProperty(object target, string name)
{
    var site = System.Runtime.CompilerServices.CallSite<Func<System.Runtime.CompilerServices.CallSite, object, object>>.Create(Microsoft.CSharp.RuntimeBinder.Binder.GetMember(0, name, target.GetType(), new[]{Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create(0,null)}));
    return site.Target(site, target);
}

Add reference to Microsoft.CSharp. Works also for dynamic types and private properties and fields.

Edit: While this approach works, there is almost 20× faster method from the Microsoft.VisualBasic.dll assembly:

public static object GetProperty(object target, string name)
{
    return Microsoft.VisualBasic.CompilerServices.Versioned.CallByName(target, name, CallType.Get);
}

This is the way i ve got the value of a property value of a dinamic:

    public dynamic Post(dynamic value)
    {            
        try
        {
            if (value != null)
            {
                var valorCampos = "";

                foreach (Newtonsoft.Json.Linq.JProperty item in value)
                {
                    if (item.Name == "valorCampo")//property name
                        valorCampos = item.Value.ToString();
                }                                           

            }
        }
        catch (Exception ex)
        {

        }


    }

In .Net core 3.1 you can try like this

d?.value2 , d?.value3

Much of the time when you ask for a dynamic object, you get an ExpandoObject (not in the question's anonymous-but-statically-typed example above, but you mention JavaScript and my chosen JSON parser JsonFx, for one, generates ExpandoObjects).

If your dynamic is in fact an ExpandoObject, you can avoid reflection by casting it to IDictionary, as described at http://msdn.microsoft.com/en-gb/library/system.dynamic.expandoobject.aspx.

Once you've cast to IDictionary, you have access to useful methods like .Item and .ContainsKey

The easiest method for obtaining both a setter and a getter for a property which works for any type including dynamic and ExpandoObject is to use FastMember which also happens to be the fastest method around (it uses Emit).

You can either get a TypeAccessor based on a given type or an ObjectAccessor based of an instance of a given type.

Example:

var staticData = new Test { Id = 1, Name = "France" };
var objAccessor = ObjectAccessor.Create(staticData);
objAccessor["Id"].Should().Be(1);
objAccessor["Name"].Should().Be("France");

var anonymous = new { Id = 2, Name = "Hilton" };
objAccessor = ObjectAccessor.Create(anonymous);
objAccessor["Id"].Should().Be(2);
objAccessor["Name"].Should().Be("Hilton");

dynamic expando = new ExpandoObject();
expando.Id = 3;
expando.Name = "Monica";
objAccessor = ObjectAccessor.Create(expando);
objAccessor["Id"].Should().Be(3);
objAccessor["Name"].Should().Be("Monica");

var typeAccessor = TypeAccessor.Create(staticData.GetType());
typeAccessor[staticData, "Id"].Should().Be(1);
typeAccessor[staticData, "Name"].Should().Be("France");

typeAccessor = TypeAccessor.Create(anonymous.GetType());
typeAccessor[anonymous, "Id"].Should().Be(2);
typeAccessor[anonymous, "Name"].Should().Be("Hilton");

typeAccessor = TypeAccessor.Create(expando.GetType());
((int)typeAccessor[expando, "Id"]).Should().Be(3);
((string)typeAccessor[expando, "Name"]).Should().Be("Monica");

Dynamitey is an open source .net std library, that let's you call it like the dynamic keyword, but using the a string for the property name rather than the compiler doing it for you, and it ends up being equal to reflection speedwise (which is not nearly as fast as using the dynamic keyword, but this is due to the extra overhead of caching dynamically, where the compiler caches statically).

Dynamic.InvokeGet(d,"value2");