Calling Extension Method to new Class - asp.net-mvc

I am new to ASP.NET MVC and even newer to Extension Methods.
I have an extension Method I wrote
public static string ExtensionMethod(this Extension extype)
{
switch (extype)
{
case Extension.ONE:
return "Object one string";
case Extension.TWO:
return "Object two string ";
case Extension.THREE:
return "Object three string";
default:
return "Any other string";
}
}
So basically what this does is compare selections that have been made in the view and changes the label to match what they selected. Easy Peasy.
Now they want their reciept to reflect that exact string. So I have a class that manages my e-mails but I can't figure out how to put the value in the class.
in my view I call
#Model.ViewModelReference.Extension();
this brings it in great, but I have no idea how to reference an extension class in another class
email.To = receiptInfo.EmailAddress;
email.From = "email address";
email.Subject = "Reciept";
var bodyFormat = new StringBuilder();
bodyFormat.AppendLine("*RECEIPT*\t");
bodyFormat.AppendLine("I want Object string to show up here");
EDIT
Thank you. I implemented it like this
bodyFormat.AppendLine(MyNameSpace.MyExtension.Extension());
but I am getting an argument error, and I am not 100% sure which argument I should put in it, or it it even needs one. If I don't add the () it throws a cannot convert to string error. through logic I put in extype but it doesn't like that either, says it doesn't exist in the current context.

You simply have to include the class that the extension method is in and the extension method will be available.
In you class that manages e-mails add:
using MyNameSpace.MyExtension;
Then to use it, just have something of type Extension and call ExtensionMethod() off of it. So it would look something like:
using MyNameSpace.MyExtension;
var myExtension = new Extension();
myExtension.ExtensionMethod()
You cannot simply call MyNameSpace.MyExtension.Extension(), you need an instance of MyExtension, which is why in my example I have myExtension variable.

Related

Get the name of a Dart class as a Type or String

Problem I need to solve
Is there a way to get the class name of a dart class as a String or a Type object..?
class MyClass {
}
var myClass = MyClass();
I know the property, runtimeType which return the type of the object as a Type object. But is there a similar function for classes?
print(myClass.runtimeType.toString());
What I currently do is creating an object of the class and use runtimeType.
String type = MyClass().runtimeType.toString();
Note: In python there is a variable called __name__ in every class, which does what I need.
My intention
My final goal is to create dart objects using previously saved class names. In this issue they have proposed a method using Maps.
The thing is that I have lots of classes and that method looks messy in my situation.
What I currently do is, save the object type by:
var saving = myClass.runtimeType.toString();
And when loading:
if (saving == MyClass().runtimeType.toString()) {
return MyClass();
}
From your experiences and opinions, can you propose a better solution?
You can use:
var runtimeTypeName = (MyClass).toString();
or for generics:
var runtimeTypeName = T.toString();
The class type can be used as a Type:
Type myType = MyClass;

FLUTTER How to get variable based on passed string name?

I have stored variables in a class with their code names.
Suppose I want to get XVG from that class, I want to do
String getIconsURL(String symbol) {
var list = new URLsList();
//symbol = 'XVG'
return list.(symbol);
}
class URLsList{
var XVG = 'some url';
var BTC = 'some url';
}
Can someone help me achieve this or provide me with a better solution?
Dart when used in flutter doesn't support reflection.
If it's text that you want to have directly in your code for some reason, I'd advise using a text replace (using your favourite tool or using intellij's find + replace with regex) to change it into a map, i.e.
final Map<String, String> whee = {
'XVG': 'url 1',
'BTC': 'url 2',
};
Another alternative is saving it as a JSON file in your assets, and then loading it and reading it when the app opens, or even downloading it from a server on first run / when needed (in case the URLs need updating more often than you plan on updating the app). Hardcoding a bunch of data like that isn't necessarily always a good idea.
EDIT: how to use.
final Map<String, String> whee = .....
String getIconsURL(String symbol) {
//symbol = 'XVG'
return whee[symbol];
}
If you define it in a class make sure you set it to static as well so it doesn't make another each time the class is instantiated.
Also, if you want to iterate through them you have the option of using entries, keys, or values - see the Map Class documentation
I'd just implement a getProperty(String name) method or the [] operator like:
class URLsList{
var XVG = 'some url';
var BTC = 'some url';
String get operator [](String key) {
switch(key) {
case 'XVG': return XVG;
case 'BTC': return BTC;
}
}
}
String getIconsURL(String symbol) {
var list = new URLsList();
return list[symbol];
}
You can also use reflectable package that enables you to use reflection-like code by code generation.
Assuming that the class is being created from a JSON Object, you can always use objectName.toJSON() and then use the variable names are array indices to do your computations.

Class create an instance of itself

I want an instance method of a class to create an instance of itself
and append it to an array.
I tried this:
var vampireArray: [Vampire] = []
class Vampire {
func createSelf() {
vampireArray.append(Vampire())
}
}
but I get a strange error on console like (lldb)
Any ideas why?
Even without knowing the context to this code, in general, creating and then appending an instance of a class to an array outside of the scope of the class is a bad idea.
Instead, try putting the line vampireArray.append(Vampire()) wherever you were originally planning to put createSelf().
If you wanted to stick with this route, it would seem like the method createSelf() should be a static method and var vampireArray: [Vampire] = [] should also be a static variable inside your class.
EDIT:
If all you want to do is keep track of the number of vampires, this could be a good solution:
class Vampire {
static var VampireCount = 0
init(){
Vampire.VampireCount += 1
}
}
Then, whenever you wanted to access the count, just use Vampire.VampireCount

The use of singleton class in objective c and swift

I have a project implemented in both Objective C and Swift classes and I need to have global variables to be shared among these classes .
I have two variables currentUsername and currentUsernumber , I need to use these two in each view in the project, what is the best way to implement that ?
I have tried to implement singleton class and here is my code :
class curentUserSingleton {
static var instance: curentUserSingleton!
var currentUsername: String = ""
var currentUsernumber: String = ""
// SHARED INSTANCE
class func sharedInstance(Name : String , Number : String) -> curentUserSingleton {
self.instance = (self.instance ?? curentUserSingleton(uName: Name , uNumber: Number))
return self.instance
}
// METHODS
init(uName : String , uNumber : String) {
self.currentUsername = uName
self.currentUsernumber = uNumber
}}
But I don't know how to use this class safely in the OC and Swift and I am a little confused since I get declaration errors when I use the class in my code!
Is this the right way to write a singleton class and how to call it in both languages ?
I'd be inclined to do something like:
class User: NSObject {
static let sharedInstance = User()
var name: String?
var number: String?
}
Then you can set and retrieve name and number like so in Swift:
User.sharedInstance.name = "Foo"
User.sharedInstance.number = "42"
print(User.sharedInstance.name)
print(User.sharedInstance.number)
Obviously, to access this from Objective-C .m file, you have to have to include the system generated header like so:
#import "ModuleName-Swift.h" // obviously, replace `ModuleName` with the name of your module
But then the syntax for setting and retrieving these properties is similar as it was in Swift:
[User sharedInstance].name = #"Foo";
[User sharedInstance].number = #"42";
NSLog(#"%#", [User sharedInstance].name);
NSLog(#"%#", [User sharedInstance].number);
To me it seems you do not need a singleton at all. I suggest you would be best of redesigning the architecture to have a user class that can store the information you are needing (and more if you finds the need in the future).
Then you could either pass that user object around between the view controllers as they need or perhaps easier define a currentUser property for the app delegate class.
That way each view controller can obtain the app delegate from the NSApp global reference to the application object and then get the current user object from there. With this pattern the app delegate acts as the globally accessible singleton you need without any need to manage it yourself.

Grails : Overriding getter method in domain class

I can't override grails getter method and becoming crazy.
What I want is use a double value and a string value to get a formatted data, but when I'm typing my override method into String, the double value is null and when into double, it obviously get me an error because a String is returned !
I get a domain class like that :
class Project {
...
String currency
Double initialTargetAmount
...
}
First Override method (initialTargetAmount is null in this case) :
//#Override Comment or uncomment it does not make any change to the behaviour
public String getInitialTargetAmount() {
println "${initialTargetAmount} ${currency}" // display "null EUR"
"${initialTargetAmount} ${currency}" // initialTargetAmount is null
}
Second method :
//#Override Comment or uncomment it does not make any change to the behaviour
public Double getInitialTargetAmount() {
println "${initialTargetAmount} ${currency}" // display "1000.00 EUR"
"${initialTargetAmount} ${currency}" // Error : String given, Double expected
}
Any help is welcome.
Snite
Groovy has dynamic getters and setters.
So, initalTargetAmount field "creates" automatically a Double getInitialTargetAmount method. Which is why it works when you have the Double return Type. But when you set String, getInitialTargetAmount automatically refers to a field String initalTargetAmount which doesn't exist
Try changing the name of the method, for example getInitialAmountWithCurrency() and it will work. Maybe your best bet will be to override toString() method ^^
Your getter should be always the same type of your field, and it's noot a good approach to change the getter like this, because Grails (Hibernate internally) will understand that your object instance changed and will try to update it ( it will check the old and new values).
You're trying in fact is to have a String representation of your amount, so you have a couple of options to this:
1 - A new method
Creating a new method that returns String will not interfere in the hibernate flow and you can use it anywere.
class Project {
...
String currency
Double initialTargetAmount
...
String displayTargetAmount() {
"${initialTargetAmount} ${currency}"
}
}
2 - TagLib
Depending on your needs, you could create a TagLib to make this custom representations of your class. This can include html formatting.
class ProjectTagLib {
static namespace = "proj"
def displayAmount = { attrs ->
if(!attrs.project) {
throwTagErrro("Attribute project must be defined.")
}
Project project = attrs.remove('project')
//just an example of html
out << "<p>${project.initialTargetAmount} , ${project.currency}</p>"
}
}

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