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Check if method/property in AppDelegate exists


Check if method/property in AppDelegate exists

By : Elena Fragasso
Date : November 19 2020, 03:54 PM
Any of those help I try to find out if the AppDelegate contains a certain property/method. For this I found Check if a property exist in a class and How to check whether an object has certain method/property?, but the AppDelegate seems to be different. , Finally I found a solution. First you need two extension methods:
code :
public static class GeneralExtensions
{
    public static bool HasProperty(this object obj, string propertyName)
    {
        return obj.GetType().GetProperty(propertyName) != null;
    }

    public static bool HasMethod(this object objectToCheck, string methodName)
    {
        var type = objectToCheck.GetType();
        return type.GetMethod(methodName) != null;
    } 
}
if (UIApplication.SharedApplication.Delegate.HasMethod("YourMethod")){
    // do something
}
if (UIApplication.SharedApplication.Delegate.HasProperty("Instance"))
    // do something
}


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How to check if a COM property or method exists without generating an exception?

How to check if a COM property or method exists without generating an exception?


By : Fábio Picheli
Date : March 29 2020, 07:55 AM
this will help Most probably the COM class implements also the IDispatch interface. You could then use its GetIDsOfNames to check whether a member exists in the class.
Here someone calls it from C#:
How to check if property exists in Type in an extension method?

How to check if property exists in Type in an extension method?


By : Aiza Egembaeva
Date : March 29 2020, 07:55 AM
wish of those help I frequently have code like this: , At first glance, the reaction would be : create an interface
code :
public interface ObjectWithDepartmentInterface {
    int depID;
}
where T : ObjectWithDepartmentInterface
where T:
if (typeof(T).GetProperty("depId") == null)
   throw InvalidOperationException (string.Format("{0}" doesn't have a depId property, typeof(T).Name))
public static IQueryable<T> WhereExistsOrAll<T>(this IQueryable<T> source, string propertyName, int value)
        where T: // is what?
{
    if (value == 0)
    return source;
    var parameter = Expression.Parameter(typeof(T), "m");
    Expression member = parameter;
    member = Expression.Property(member, propertyName);
    member = Expression.Equals(member, Expression.Constant(value));
    var lambda = Expression.Lambda<Func<T, bool>>(member, new[]{parameter});
    return source.Where(lambda);
}
var stRecs = db.<someTable>.WhereExistsOrAll("depId", depId);
public static IQueryable<T> GetAllOrRestrict<T>(this IQueryable<T> queryable, Expression<Func<T, bool>> predicate)
{
       var expression = predicate.Body as BinaryExpression;

       var rightPart = expression.Right as MemberExpression;
       var value = GetValue(rightPart);
       var test = value.ToString();
       int val;
       if (Int32.TryParse(value.ToString(), out val))
       {
           if (val != 0)
               return queryable.Where(predicate);
       }

       return queryable;
}

private static object GetValue(MemberExpression member)
{
     var objectMember = Expression.Convert(member, typeof(object));
     var getterLambda = Expression.Lambda<Func<object>>(objectMember);
     var getter = getterLambda.Compile();
     return getter();
}
var stRecs = db.<someTable>.GetAllOrRestrict(m => m.depID == depId);
Check if property or method exists at runtime? Check if Trait exists at runtime?

Check if property or method exists at runtime? Check if Trait exists at runtime?


By : Kelly
Date : March 29 2020, 07:55 AM
wish help you to fix your issue This concept doesn't exist in Rust. While there is some limited downcast capability through Any, this should be used as a last resort. What you should do is create a new trait that exposes all of these decisions for you.
Reusing your example of a my_method method:
code :
trait YourTrait {
    fn try_my_method(&self, arg: SomeArg) -> Option<MyMethodResult> {
        None
    }
}

impl YourTrait for SomeType {
    fn try_my_method(&self, arg: SomeArg) -> Option<MyMethodResult> {
        Some(self.my_method(arg))
    }
}
if let Some(result) = self.try_my_method() {
    /* ... */
}
Check if document exists? Response payload doesn't have property exists

Check if document exists? Response payload doesn't have property exists


By : Johan Wullus
Date : March 29 2020, 07:55 AM
To fix this issue What you're looking for is in x.payload.exists.
The snapshot represents changes that have been made, you have to access the payload to know if it exists or not.
code :
this.angularFirestore.doc(`users/${credentials.user.uid}`)
    .snapshotChanges()
    .subscribe(x => console.log(x.payload.exists))
Typescript. Check if method/property exists in the variable of unknown type

Typescript. Check if method/property exists in the variable of unknown type


By : user3136544
Date : March 29 2020, 07:55 AM
I hope this helps you . The thing with unknown is that you have to narrow its type before you can use it. You can use a custom type guard for this:
code :
interface ArrayProp {
  arrayProp: []
}
function isArrayProps(value: unknown): value is ArrayProp {
  return !!value && !!(value as ArrayProp).arrayProp;
}

function handle(data: unknown) {
   if (isArrayProps(data) && typeof data.arrayProp[Symbol.iterator] === 'function') {
   }
}
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