Given this class
class Foo
{
// Want to find _bar with reflection
[SomeAttribute]
private string _bar;
public string BigBar
{
get { return this._bar; }
}
}
I want to find the private item _bar that I will mark with a attribute. Is that possible?
I have done this with properties where I have looked for an attribute, but never a private member field.
What are the binding flags that I need to set to get the private fields?
Use BindingFlags.NonPublic and BindingFlags.Instance flags
FieldInfo[] fields = myType.GetFields(
BindingFlags.NonPublic |
BindingFlags.Instance);
You can do it just like with a property:
FieldInfo fi = typeof(Foo).GetField("_bar", BindingFlags.NonPublic | BindingFlags.Instance);
if (fi.GetCustomAttributes(typeof(SomeAttribute)) != null)
...
You can access any private field of an arbitrary type with code like this:
Foo foo = new Foo();
string c = foo.GetFieldValue<string>("_bar");
For that you need to define an extension method that will do the work for you:
public static class ReflectionExtensions {
public static T GetFieldValue<T>(this object obj, string name) {
// Set the flags so that private and public fields from instances will be found
var bindingFlags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
var field = obj.GetType().GetField(name, bindingFlags);
return (T)field?.GetValue(obj);
}
}
One thing that you need to be aware of when reflecting on private members is that if your application is running in medium trust (as, for instance, when you are running on a shared hosting environment), it won't find them -- the BindingFlags.NonPublic option will simply be ignored.
Yes, however you will need to set your Binding flags to search for private fields (if your looking for the member outside of the class instance).
The binding flag you will need is: System.Reflection.BindingFlags.NonPublic
If your .Net framework is greater than 4.5. You can use GetRuntimeFields method.
This method returns all fields that are defined on the specified type, including inherited, non-public, instance, and static fields.
var foo = new Foo();
var fooFields = foo.GetType().GetRuntimeFields()