C#: How to perform a null-check on a dynamic object

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How do I perform a null-check on a dynamic object?

Pseudo code:

public void Main() {
    dynamic dynamicObject = 33;
    if(true) { // Arbitrary logic
        dynamicObject = null;
    }
    Method(dynamicObject);
}

public void Method(dynamic param) {
    // TODO: check if the content of 'param' is equal to null
}

Are you worried about the possibility the dynamic object will have a custom equality operator that will change the way the null is interpreted? If so just use Object.ReferenceEquals

if (Object.ReferenceEquals(null, param)) {
  .......
}

How to check for null/empty strings on dynamic objects?, String object. This makes it impossible to do regular "admin.PasswordHash == DBNull.Value" check, as that will fail whenever the field has  In-that situation you have to write explicit null-ability check of the object before invoking method or property. To address the run-time null reference exception issue and to reduce the duplicate code for each null check , C#6.0 introduced null-conditional operator (?.) .

You can always just make the param of type object, that's what the compiler is doing. When you type a parameter dynamic it just means within that method only it is using dynamic invoke for all uses of param, but outside it's just a signature of type object. A more powerful usage of your dynamicObject would be to have overloads of the method you are calling, so if you keep your example the same and just have two overloads it would call one of the two methods based on the runtime type, and you can always add more for more types.

public void Main() {
    dynamic dynamicObject = 33;
    if(true) { // Arbitrary logic
        dynamicObject = null;
    }
    Method(dynamicObject);
}
public void Method(int param) {
  //don't have to check check null
  //only called if dynamicObject is an int
}
public void Method(object param) {
// will be called if dynamicObject is not an int or null
}

Generic Null/Empty check for each property of a class, You do not need to declare a local variable for result , simply return its value You do not need to use to dynamic , when casting you have the right type at  I'm looping through a property on a dynamic object looking for a field, except I can't figure out how to safely evaluate if it exists or not without throwing an exception. foreach (dynamic item in routes_list["mychoices"]) { // these fields may or may not exist int strProductId = item["selectedProductId"]; string strProductId = item

Fast way might be:

if (_owner is null)
{

}

Programming Languages and Systems: 9th European Symposium on , A;C;FI-,v(v1,,v,,) I-S:C 4.1 Non-linear Constraints and Dynamic Type Tests can use weak constraints to perform a dynamic type test on a particular object and name p with null and the tosum v, T instruction injects the value v (a location  Dynamic behind the scenes is just object. That is, a "dynamic" variable is an "object" variable with a hint to the compiler that says "generate dynamic operations on this variable when it is used." There is no such thing as a boxed nullable. When you box an int? to object you get either a null object reference or a boxed int.

You can use simplicity:

var s = data.servicePhoneNumber is null ? "" : data.servicePhoneNumber.Value;

Object Oriented Programming Using C++: An Introduction, Note that we cannot do this as part of the object class definition. to initialise the array of pointers so that each element has a value of NULL. The purpose of the destructor is to ensure that any memory allocated for dynamic objects (this is  You reference a dynamic object by using late binding. In C#, you specify the type of a late-bound object as dynamic. In Visual Basic, you specify the type of a late-bound object as Object. For more information, see dynamic and Early and Late Binding. You can create custom dynamic objects by using the classes in the System.Dynamic namespace.

Ada: Concurrent Programming, The value returned by new must be used to reference the dynamic object. All access type objects are by default initialized to the the null value. a record, then the record component c is referenced asp. c. Inaccessible objects may be automatically deallocated if the Ada implementation performs “garbage” collection. I know this is really old post but here is a simple solution to work with dynamic type in c#. can use simple reflection to enumerate direct properties. or can use the object extention method. or use GetAsOrDefault<int> method to get a new strongly typed object with value if exists or default if not exists.

Working with the Dynamic Type in C#, Dynamic objects let you work with structures such as JSON documents of the Dynamic Language Runtime (DLR), what does this say about C#? . Let's take a closer look at the dynamic keyword and explore what it can do. Note that I safely cast serializer results into a dynamic type with null checks. This works for anonymous types, ExpandoObject, Nancy.DynamicDictionary or anything else that can be cast to IDictionary<string, object>. public static bool PropertyExists(dynamic obj, string name) { if (obj == null) return false; if (obj is IDictionary<string, object> dict) { return dict.ContainsKey(name); } return obj.GetType().GetProperty(name) != null; }

Using type dynamic, https://docs.microsoft.com › Docs › .NET › C# guide › Language reference Given a dynamic type: dynamic dynVar; Type type; A merely declared, uninitialized dynamic variable dynVar will throw an exception of Type Microsoft.CSharp.RuntimeBinder.RuntimeBinderException as you are performing runtime binding on a null reference, when performing Type-Reflection via dynVar.GetType().

Comments
  • @Ani not sure what' your getting at there.
  • You could just write ReferenceEquals(null, param). I can't believe from the ~5 questions on this topic at SO didn't solve it this simply.
  • @JaredPar: Since all C# types that can contain method definitions extend System.Object (AFAIK), it isn't necessary to qualify. (Not all that important really.)
  • @JaredPar: Fair enough. Of course, the containing type could contain a member called Object with an instance method called ReferenceEquals with different behaviour too..
  • @Ani definitely. For me that borders on being evil and virtually every code sample can be defeated by someone being evil.