I'm trying to convert a PublishSubject:
rx.subjects.PublishSubject<String> sj = rx.subjects.PublishSubject.create();
PublishSubject<String> sj2 = RxJavaInterop.toV2Subject(sj);
But the IDE said that can not apply rx.subjects.Subject< T, T> to rx.subjects.PublishSubject< java.lang.String>.
You can't convert it to a v2 PublishSubject because subject implementations are final and can't wrap other subjects, thus, as the method's return type indicates, you have to use a io.reactivex.subjects.Subject<String> as a type:
rx.subjects.PublishSubject<String> sj = rx.subjects.PublishSubject.create();
io.reactivex.subjects.Subject<String> sj2 = RxJavaInterop.toV2Subject(sj);
Related
I'm trying to loop through two lists at the same time
For example
List A = ['Chapter 1','Chapter 2','Chapter 3'];
List B = ['Paragraph 1','Paragraph 2','Paragraph 3'];
for(var chapter in A) // This would itreate through only first list (A), How can I iterate through both list
children: [
Text(chapter);
Text(paragraph);
]
I need to iterate through both lists at the same time in "for" loop.
Here is the code:
List A = ['Chapter 1','Chapter 2','Chapter 3'];
List B = ['Paragraph 1','Paragraph 2','Paragraph 3'];
for (int i = 0; i < A.length; i++) {
print ("${A[i]}");
print ("${B[i]}");
}
Let me know if this does not help.
final c = zip([a, b]).map((item) => Foo(item[0], item[1])).toList();
I went along with Randal Schwartz's note about IterableZip. Note that I was not able to find any zip mentioned by Gbenga, and also note that package:collection/iterable_zip.dart is deprecated, you'd need to import simply the collection.dart, like so:
import 'package:collection/collection.dart';
final A = ['Chapter 1','Chapter 2','Chapter 3'];
final B = ['Paragraph 1','Paragraph 2','Paragraph 3'];
for (final pairs in IterableZip([A, B])) {
print(pairs[0]);
print(pairs[1]);
}
Some more notes:
final A and final B variables will be typed List<String> lists, I disadvise dynamic List A.
I have not specified template type for IterableZip, but in some cases (in a complex case where I used it) you may need to explicitly type it like IterableZip<String>, so in the loop you can more conveniently access the members. In this simple case the compiler/interpreter can infer the type easily.
Some other answers in other StackOverflow issues mention quiver, but unless you need it for some other features you don't have to add another extra package dependency to your project. The standard collection package has this IterableZip
I am working with spring data jpa, I would like to know in QueryByExample(QBE) can i get all the records (where colum value not equals 'XXX')
I have seen ExampleMatcher , but couldnt find anything like not equals
Employee filterBy = new Employee();
filterBy.setLastName("ar");
//Filter - ignore case search and contains
ExampleMatcher matcher = ExampleMatcher.matching()
.withStringMatcher(StringMatcher.CONTAINING) // Match string containing pattern
.withIgnoreCase(); // ignore case sensitivity
example = Example.of(filterBy, matcher);
The above code gets all the records where lastname is ar, but i am looking for lastname should not be "ar".
Is there any other ExampleMatcher ?
BizExceptionConfig condition = configRequestPair.getCondition();
ExampleMatcher exampleMatcher = ExampleMatcher.matching()
.withMatcher("appCode", startsWith())
.withMatcher("name", startsWith())
.withMatcher("code", startsWith());
if(Objects.isNull(condition.getLifecycle())){
condition.setLifecycle(LifeCycle.DELETE.getCode());
HashMap<String, Integer> params = new HashMap<>();
params.put("$ne", LifeCycle.DELETE.getCode());
exampleMatcher = exampleMatcher.withTransformer("lifecycle", (obj) -> Optional.of(params));
}
Example<BizExceptionConfig> example = Example.of(condition, exampleMatcher);
Page<BizExceptionConfig> pageRecord = bizExcConfigRepository.findAll(example, PageUtil.toPageRequest(configRequestPair.getPage()));`enter code here`
This problem can be solved by "withTransformer". JPA is rather limited,
so I suggest using Mongotmpl. I hope it can help you
Your problem could be solved with QBE by using REGEX as StringMatcher and the solution would look like the following:
Employee filterBy = new Employee();
filterBy.setLastName("ar");
filterBy.setLastName(String.format("^(?!.*$1$).*$", Pattern.quote(filterBy.getLastName())));
//filterBy.setLastName(String.format(".*(?<!$1)$", Pattern.quote(filterBy.getLastName()))); // this would be another alternative
ExampleMatcher matcher = ExampleMatcher.matching()
.withStringMatcher(StringMatcher.REGEX) // Match string containing pattern
.withIgnoreCase(); // ignore case sensitivity
Example example = Example.of(filterBy, matcher);
Unfortunately, even though the developer would at first think that Regular Expressions are supported (as there exists aforementioned enum constant), Spring actually currently doesn't support them - and according to the discussion of the related Jira issue, it never won't: https://jira.spring.io/browse/DATAJPA-944
In the non reactive world the following code snippet is nothing special:
interface Enhancer {
Result enhance(Result result);
}
Result result = Result.empty();
result = fooEnhancer.enhance(result);
result = barEnhancer.enhance(result);
result = bazEnhancer.enhance(result);
There are three different Enhancer implementations taking a Result instance, enhancing it and returning the enhanced result. Let's assume the order of the enhancer calls matters.
Now what if these methods are replaced by reactive variants returning a Flux<Result>? Because the methods depend on the result(s) of the preceding method, we cannot use combineLatest here.
A possible solution could be:
Flux.just(Result.empty())
.switchMap(result -> first(result)
.switchMap(result -> second(result)
.switchMap(result -> third(result))))
.subscribe(result -> doSomethingWith(result));
Note that the switchMap calls are nested. As we are only interested in the final result, we let switchMap switch to the next flux as soon as new events are emitted in preceding fluxes.
Now let's try to do it with a dynamic number of fluxes. Non reactive (without fluxes), this would again be nothing special:
List<Enhancer> enhancers = <ordered list of different Enhancer impls>;
Result result = Result.empty();
for (Enhancer enhancer : enhancers) {
result = enhancer.enhance(result);
}
But how can I generalize the above reactive example with three fluxes to deal with an arbitrary number of fluxes?
I found a solution using recursion:
#FunctionalInterface
interface FluxProvider {
Flux<Result> get(Result result);
}
// recursive method creating the final Flux
private Flux<Result> cascadingSwitchMap(Result input, List<FluxProvider> fluxProviders, int idx) {
if (idx < fluxProviders.size()) {
return fluxProviders.get(idx).get(input).switchMap(result -> cascadingSwitchMap(result, fluxProviders, idx + 1));
}
return Flux.just(input);
}
// code using the recursive method
List<FluxProvider> fluxProviders = new ArrayList<>();
fluxProviders.add(fooEnhancer::enhance);
fluxProviders.add(barEnhancer::enhance);
fluxProviders.add(bazEnhancer::enhance);
cascadingSwitchMap(Result.empty(), fluxProviders, 0)
.subscribe(result -> doSomethingWith(result));
But maybe there is a more elegant solution using an operator/feature of project-reactor. Does anybody know such a feature? In fact, the requirement doesn't seem to be such an unusual one, is it?
switchMap feels inappropriate here. If you have a List<Enhancer> by the time the Flux pipeline is declared, why not apply a logic close to what you had in imperative style:
List<Enhancer> enhancers = <ordered list of different Enhancer impls>;
Mono<Result> resultMono = Mono.just(Result.empty)
for (Enhancer enhancer : enhancers) {
resultMono = resultMono.map(enhancer::enhance); //previousValue -> enhancer.enhance(previousValue)
}
return resultMono;
That can even be performed later at subscription time for even more dynamic resolution of the enhancers by wrapping the whole code above in a Mono.defer(() -> {...}) block.
I have a Flux and Mono as below:
Mono<MyRequest> req = request.bodyToMono(MyRequest.class);
Mono<List<String>> mono1 = req.map(r -> r.getList());;
Flux<Long> flux1 = req.map(r -> r.getVals()) // getVals() return list of Long
.flatMapMany(Flux::fromIterable);
Now for each number in flux1, I want to call a method where params are the id from flux1 and the List<String> from mono1. Something like,
flux1.flatMap(id -> process(id, mono1))
But passing and processing same mono1 results in error Only one connection receive subscriber allowed. How can I achieve above? Thanks!
Since both information are coming from the same source, you could just run the whole thing with one pipeline like this and wrap both elements in a Tuple or better, a domain object that has more meaning:
Mono<MyRequest> req = // ...
Flux<Tuple2<Long, List<String>>> tuples = req.flatMapMany(r ->
Flux.fromIterable(r.getVals())
.map(id -> Tuples.of(id, r.getList()))
);
// once there, you can map that with your process method like
tuples.map(tup -> process(tup.getT1(), tup.getT2());
Note that this looks unusual, and this basically comes from the structure of that object you're receiving.
I can send callback param(s) and it works perfectly as long as I am only sending some primitive types like String. But the same thing does not work for even the simplest POJO. PrimeFaces guide says that the RequestContext.addCallbackParam() method can handle POJOs and it coverts them into JSON. I don't know why it's not working in my case.
Has anybody done that?
Solution found! ---------------------------------------------------------------------
I did some research and found the answer to this question.
And the solution was to use some JSON library (right now I am using GSON) to convert Java objects to JSON objects.
new Gson().toJson(someJavaObj)
returns string. Just send the string as the param and on the client side using js' eval or some js library's function to turn that into JSON again.
Actually, it was pretty clean and simple.
Sorry I actually did not post the solution. Below is the my solution -
Action method in the backing bean -
public void retrievePieData() {
List<String> categories = new ArrayList<String>();
categories.add("Electronic");
categories.add("Food");
categories.add("Liguor");
categories.add("Stationary");
categories.add("Mechanical");
List<Integer> itemCounts = new ArrayList<Integer>();
itemCounts.add(5);
itemCounts.add(20);
itemCounts.add(1);
itemCounts.add(50);
itemCounts.add(10);
RequestContext reqCtx = RequestContext.getCurrentInstance();
reqCtx.addCallbackParam("categories", new Gson().toJson(categories));
reqCtx.addCallbackParam("itemCounts", new Gson().toJson(itemCounts));
}
PrimeFaces p:commandButton in the view -
<p:commandLink action="#{pieDataProvider.retrievePieData}" oncomplete="feedPieData(xhr, status, args);" value="Pie chart demo" update="pieData" />
Javascript function -
function feedPieData(xhr, status, args) {
var categories = eval('(' + args.categories + ')');
var itemCounts = eval('(' + args.itemCounts + ')');
options.xAxis.categories = categories;
var series = {
data: []
};
series.name = new Date().toString();
series.data = itemCounts;
options.series = [series];
chart = new Highcharts.Chart(options);
}
I would really appreciate and welcome any suggestion or opinion.
Thank you!