I want to discuss the options i have come across for calling a native method from a IOS ViewManager/View in JS side without using properties but direct method calls.
Option A:
implementing a method in the ViewManager which searches for the correct view and calls the given method in the view, like this:
func callMethodViaManager(_ node:NSNumber) {
DispatchQueue.main.async {
let myView = self.bridge.uiManager.view(forReactTag: node) as! MyView
myView.myMethod()
}
}
and then in the JS side implement a handler like this:
const handleSomething = (e) => {
UIManager.dispatchViewManagerCommand(
ReactNative.findNodeHandle(ref.current),
UIManager.SwiftComponent.Commands.callMethodViaManager,
[])
};
This is just a short summary of the relevant parts, the process in full can be seen in full detail maybe just a bit old but with some adjustments one can get it to work also with functional components:
https://medium.com/#jjdanek/react-native-calling-class-methods-on-native-swift-views-521faf44f3dc
Option B:
For this option let's go with the best scenario which is that one can get all the necessary data, setup, etc on the ViewManager ready via delegates for example or some other pattern or Swift sugar.
Calling the Native methods in the ViewManager from the JS side directly with the use of NativeModules, like this:
const handleSomething = (e) => {
NativeModules.MyViewManager.myMethod()
};
I could not find much about this option in correlation to a Native View being bridged, this way of doing it is used for Native Module bridging explicitly. The only things i could find where:
React Native UI Component Method
or guides like these one:
https://teabreak.e-spres-oh.com/swift-in-react-native-the-ultimate-guide-part-1-modules-9bb8d054db03#4377
I have tried both methods and at first glance they seem to work both.
So my questions are:
Why is Option A the better solution/option and the one which is recommended or most used?
What is wrong or can go wrong with Option B?
Is there anything else to take into consideration?
Is there a better way which is not trough properties?
Option B is more flexible.
If you use Option A, then you can't pass Promise and Callback parameter to the native side.
It seems possible in iOS But not in Android.
This is a related issue.
React Native bridge API is all confusing
There is no guide about how to call the native UI method with Promise or Callback.
There is a example about how to pass Promise to native side with calling native UI instance method.
SketchView... is just my example module name.
class SketchViewModule(reactContext: ReactApplicationContext) : ReactContextBaseJavaModule(reactContext) {
override fun getName() = "SketchViewModule"
private fun runCommandWithPromise(
viewId: Int, promise: Promise, handler: (view: SketchView) -> Unit
) {
reactApplicationContext.getNativeModule(UIManagerModule::class.java)?.let { uiManager ->
uiManager.addUIBlock {
(it.resolveView(viewId) as? SketchView)?.let { view ->
handler(view)
} ?: run {
promise.safeReject("[runCommandWithPromise] Cannot find View with UIManager")
}
}
}
}
...
Related
I am trying to migrate from RxJava1 to RxJava2. I am replacing all code parts where I previously had Observable<Void> to Compleatable. However I ran into one problem with order of stream calls. When I previously was dealing with Observables and using maps and flatMaps the code worked 'as expected'. However the andthen() operator seems to work a little bit differently. Here is a sample code to simplify the problem itself.
public Single<String> getString() {
Log.d("Starting flow..")
return getCompletable().andThen(getSingle());
}
public Completable getCompletable() {
Log.d("calling getCompletable");
return Completable.create(e -> {
Log.d("doing actuall completable work");
e.onComplete();
}
);
}
public Single<String> getSingle() {
Log.d("calling getSingle");
if(conditionBasedOnActualCompletableWork) {
return getSingleA();
}else{
return getSingleB();
}
}
What I see in the logs in the end is :
1-> Log.d("Starting flow..")
2-> Log.d("calling getCompletable");
3-> Log.d("calling getSingle");
4-> Log.d("doing actuall completable work");
And as you can probably figure out I would expect line 4 to be called before line 3 (afterwards the name of andthen() operator suggest that the code would be called 'after' Completable finishes it's job). Previously I was creating the Observable<Void> using the Async.toAsync() operator and the method which is now called getSingle was in flatMap stream - it worked like I expected it to, so Log 4 would appear before 3. Now I tried changing the way the Compleatable is created - like using fromAction or fromCallable but it behaves the same. I also couldn't find any other operator to replace andthen(). To underline - the method must be a Completable since it doesn't have any thing meaning full to return - it changes the app preferences and other settings (and is used like that globally mostly working 'as expected') and those changes are needed later in the stream. I also tried to wrap getSingle() method to somehow create a Single and move the if statement inside the create block but I don't know how to use getSingleA/B() methods inside there. And I need to use them as they have their complexity of their own and it doesn't make sense to duplicate the code. Any one have any idea how to modify this in RxJava2 so it behaves the same? There are multiple places where I rely on a Compleatable job to finish before moving forward with the stream (like refreshing session token, updating db, preferences etc. - no problem in RxJava1 using flatMap).
You can use defer:
getCompletable().andThen(Single.defer(() -> getSingle()))
That way, you don't execute the contents of getSingle() immediately but only when the Completablecompletes and andThen switches to the Single.
I am having difficulty referring to parameterless functions in Fable.
With this example:
let f1 () =
1
let someRefTof1 = f1
I'd expect the generated js to look something like this:
function f1() {
return 1;
}
var someRefTof1 = f1;
but what I actually get is:
function f1() {
return 1;
}
var someRefTof1 = exports.someRefTof1 = function someRefTof1(arg00_) {
return f1(arg00_);
};
I'm unclear on the purpose of arg00_ or how to avoid it being generated?
(As a bit of background, I am struggling to call a function in an external js library which expects a function to be passed as a parameter)
Edit:
Background
The above is what i believe to be a minimal, verifiable, reproduction of my question but, after comments, I thought it may be useful to provide a touch more context on why this is causing issues. What I am actually trying to do is use angularjs from Fable.
So my example looks more like this:
let app = AngularFable.NgFable.angular.``module``("app",[||])
type TestCtrl() =
member this.Val1() = "boom";
app?controller("test", TestCtrl)
which gets compiled to:
var app = exports.app = angular.module("app", []);
var TestCtrl = exports.TestCtrl = function () {
function TestCtrl() {
_classCallCheck(this, TestCtrl);
}
TestCtrl.prototype.Val1 = function Val1() {
return "boom";
};
return TestCtrl;
}();
_fableCore.Util.setInterfaces(TestCtrl.prototype, [], "App.TestCtrl");
app.controller("test", function (unitVar) {
return new TestCtrl();
});
with unitVar being the problematic parameter introduced in this example. When I use this in my html with something like:
<div ng-app="app">
<div ng-controller="test as vm">
{{vm.Val1()}}
</div>
</div>
I run into an unknown provider error whereas if I simply change the compiled javascript to remove the unitVar parameter from the last line like this:
app.controller("test", function () {
return new TestCtrl();
});
then my example works as expected.
I'd really like to know if there is a way to avoid having the Fable compiler generate this parameter. I'm 99% sure this reduces to the same problem as in my original question but I've included this additional context to better explain why this is an issue
Thank you very much for your question and detailed explanations. There're two things here that are a bit tricky and are caused by optimisations both of the F# compiler and Fable.
In the AST provided by the F# compiler, methods (functions that are members of a type or module) are compiled as usual methods as in C#. This is for optimization.
However, when you create an anonymous lambda or make a reference to a method, the F# compiler will keep F# semantics, that is, all functions have a single argument (as John Palmer says, unit is an argument too) and can be curried.
Ok, this info is just to make clear why the F# compiler/Fable represent methods and lambdas differently. Let's go with the issue of argumentless functions: the obvious solution would be of course to remove the F# compiler generated argument for functions accepting unit (as it's already done for methods). In fact, I also had problems with libraries like Mocha because of this.
I did try to remove the unit argument at the beginning but I got fails in some scenarios because of this. TBH, I don't remember now exactly which tests were failing but because of the expectation that there'll be always an argument, in some cases function composition or inlining was failing when the unit argument was removed.
Other attempts to modify the semantics of F# functions in the JS runtime have always failed because they don't cover all scenarios. However, we can be more lenient with delegates (System.Func<>) as it's usually safe to assume these ones should behave more like functions in languages like C# or F#. I can try to remove the unit argument just for delegates and see what happens :)
For more info about sending F# functions to JS code you can check the documentation.
UPDATE: Scratch all that, please try fable-compiler#0.6.12 and fable-core#0.6.8. This version eliminates unit arguments, the solution was actually simpler than I thought and (hopefully) shouldn't create issues with existing projects. (The explanation about methods and lambdas compiled differently still applies.)
I'm using the HotTowel SPA template which makes use of Durandal. In my Durandal ViewModels I am using Breeze to get some data from the database.
I have a datacontext class that I put all my breeze queries in and the queries all follow the pattern like the following:
getAthletes: function (queryCompleted) {
var query = breeze.EntityQuery.from("Athletes");
return manager
.executeQuery(query)
.then(queryCompleted)
.fail(queryFailed)
}
Since I'm doing an asynchronous call in the activate method of the view model, I have to return the promise that comes back from these calls in the activate method.
Using a single query works great like this:
function activate() {
datacontext.getAthlete(loadAthlete);
}
However, if I need to perform two queries I run into problems, but only in the release version of my application. I have tried doing this with the following syntax:
function activate() {
datacontext.getAthlete(loadAthlete).then(datacontext.getOtherData(loadOtherData));
}
This will work fine in debug mode, but when I deploy it out to the server and my scripts get bundled, I get an exception which isn't very clear.
t is not a function
I've also tried chaining them together in my datacontext class like below, but I still get the same error.
getAthleteAndEfforts: function (athleteId, athleteQueryCompleted, effortsQueryCompleted) {
var athleteQuery = breeze.EntityQuery.from("Athletes").where("id", "==", athleteId);
var effortsQuery = breeze.EntityQuery.from("BestEfforts").where("athleteId", "==", athleteId);
return manager.executeQuery(athleteQuery).then(athleteQueryCompleted)
.then(manager.executeQuery(effortsQuery).then(effortsQueryCompleted))
.fail(queryFailed);
}
So I'm assuming I just don't understand the Q.defer() enough to use it properly or there is something else going on.
What is the correct syntax to accomplish this?
Ok, thanks to RainerAtSpirit for pointing me in the right direction to find this. I looked at John Papa's jumpstarter examples and he has a datacontext that does this under the primeData function.
So using the syntax he used there I was able to get it to work correctly like this:
getAthleteAndEfforts: function (athleteId, athleteQueryCompleted, effortsQueryCompleted) {
return Q.all([
datacontext.getAthlete(athleteId, athleteQueryCompleted),
datacontext.getAthleteEfforts(athleteId, effortsQueryCompleted)]);
}
I had seen the Q.all in the Q documentation but wasn't sure how to use it, but this example helped. I tested this and it works both in debug and release modes.
Not sure why the first version is working at all, but you'd return a promise when datacontext is making async calls.
function activate() {
return datacontext.getAthlete(loadAthlete);
}
or
function activate() {
return datacontext.getAthlete(loadAthlete).then( return datacontext.getOtherData(loadOtherData));
}
Check #John Papa's jumpstarter for more examples: https://github.com/johnpapa/PluralsightSpaJumpStartFinal/search?q=activate
How are you supposed to conditionally display menu items based on roles in the Bootstrap Sample project? I was thinking of doing the following
Implement INavigatonRouteFilter - really just implementing the shouldRemove(Route navigationRoutes) method - by getting the default controller/action for the route and seeing if the user is authorized
Call NavigationRoutes.Filters.Add(myAuthorizationFilter) after configuring the NavigationRoutes in App_Start
There are two problems I see with this approach:
I don't actually know how to do the first step unless I add in a bunch of conditional statements to check for Controller's name explicitly
This seems like it could make NavigationRoutes.Filters very hard to deal with once there are a lot of filters or a desire for more modularity later on
I don't know that I've explained the problem clearly enough, but basically I want to use what is provided in the Bootstrap sample to implement authorization-based navigation menu display if at all possible. Using INavigationRouteFilter just seemed like the most natural way to do so.
For those looking for an answer or at least a quick fix.
Here's what I've come up with after 5 minutes and I most certainly haven't though about any side effects this may have.
routes.MapNavigationRoute<HomeController>("Index", c => c.Index())
.FilterRoute(() => !WebSecurity.IsAuthenticated);
You can either do all your filtering in your call to FilterRoute() or you can add more extension methods to save you some characters.
I'm thinking of .RequireRole("Adiministrators"); that calls WebSecurity.RequireRoles() in turn (or HttpContext.Current.User.IsInRole()) etc.
public static NavigationRouteBuilder FilterRoute(this NavigationRouteBuilder builder, Func<bool> func)
{
var currentRoute = builder._parent;
NavigationRoutes.Filters.Add(new BootstrapAuthorizationFilter(builder, x =>
{
if (x == currentRoute)
return func();
else
return false;
}));
return builder;
}
and BootstrapAuthorizationFilter is just a class implementing INavigationRouteFilter that calls func() in its ShouldRemove() method
public class BootstrapAuthorizationFilter : INavigationRouteFilter
{
private NavigationRouteBuilder builder;
private Func<NamedRoute, bool> func;
public BootstrapAuthorizationFilter(NavigationRouteBuilder builder, Func<NamedRoute, bool> func)
{
this.builder = builder;
this.func = func;
}
public bool ShouldRemove(Route navigationRoutes)
{
if (navigationRoutes is NamedRoute)
return func(navigationRoutes as NamedRoute);
return false;
}
}
Clearly nothing fancy and I'm not sure if I'd use it in production.
But I think is simple enough and works (for the cases I tested).
Having said that, I hope the new routing functionality is going to be released soon :)
I've created a code sample that shows the issue I'm having:
class BindingExample {
public static void main(String[] args) {
Closure closure1 = {
printit.call("Hello from closure 1")
}
Closure closure2 = {
printit("Hello from closure 2")
}
Closure printit = { s ->
println("printing: "+s)
}
Binding binding = new Binding()
binding.setVariable("printit", printit)
closure1.delegate = binding
closure2.delegate = binding
closure1() //This works fine
closure2() //This does not.
//Why does .call() work and () alone not? Most documentation says they're the same.
}
}
Printit is a Closure, which the documentation indicates implements doCall and therefore is callable in short form via ().
However, when this closure is made available via binding to a delegate, only the long-form version of the call is permitted. The output is:
printing: Hello from closure 1
Exception in thread "main" groovy.lang.MissingMethodException: No signature of method: groovy.lang.Binding.printit() is applicable for argument types: (java.lang.String) values: [Hello from closure 2]
Can someone explain why this is the case? If possible, I'd like to also see how to make it so the short-form version works. I was able to make it work by defining printit as a proper static method (not a closure), but that won't work for my case because I actually need printit to be given some data available only inside of the method scope (not included in the example since my question relates to the binding itself).
As to WHY this is the case, I can't give a definite answer, unfortunately. There's some talk about implicit-"this" annotation, etc. It seems like it should work, but that there's some vagueness about what should be tried first (this-scope or delegate).
That the issue exists, currently, seems correct. I've found the following other resources that agree, with some discussion without resolution about why.
Nabble discussion about the issue:
http://groovy.329449.n5.nabble.com/Binding-Closure-property-not-called-as-method-td5562137.html
JIRA ticket resulting:
https://issues.apache.org/jira/browse/GROOVY-5367