So I'm attempting to go through a groovyObject's fields and obtain the property of that field. So this is what I got(sorry its a little rough so cleaning would be appreciated but not necessary, I'm also doing a little debugging and other stuff with the Log and what not.):
public void traverse(final GroovyObject groovy) throws RepositoryException, NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException
{
Field[] theFields = groovy.getClass().getDeclaredFields();
final ArrayList<Field> fields = new ArrayList<Field>();
int count =0;
for(Field field : theFields)
{
fields.add(field);
LOG.error("{} = {}",field.getName(), groovy.getProperty(field.getName()));
}
//this is the guava tree traverser
TreeTraverser<GroovyObject> traverser = new TreeTraverser<GroovyObject>()
{
#Override
public Iterable<GroovyObject> children(GroovyObject root)
{
return (Iterable<GroovyObject>)root.getProperty(fields.get(0).getName());
//|-->Here I get the String cannot be cast to Iterable. Which I find odd since it is still an object just getProperty takes a string. right?
}
};
Thoughts on this? Thanks for the help!
GroovyObject.getProperty(String) retrieves the value of the given property. And if that value happens to be a String you cannot cast it to Iterable.
If you adjust your log statement, you can inspect the types of the fields:
LOG.error("{} of type {} = {}", field.getName(), field.getType(), groovy.getProperty(field.getName()));
So I figured it outl. Essentially what needs to happen is I need to make two iterators: one for the groovy objects and one for the property strings so the end goal looks like
groovyObject.iterate().next().getProperty(string.iterate().next());
Or something like that, I will update this when I figure it out.!
Once I make that I can go back in and think about making it more efficient
Related
I receive a List of MediaDTO and this Object has two attributes:
String sizeType and String URL.
In 'sizeType' comes the image´s size: small, medium, large, and thumbnail.
So I have to filter the sizeType of these objects and create 4 new lists based on them.
This is how I get the List<MediaDTO> mediaDTO:
medias=[MediaDTO(sizeType=THUMBNAIL, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/thumbnail/celular-iphone-11-azul.png), MediaDTO(sizeType=SMALL, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/small/celular-iphone-11-azul.png), MediaDTO(sizeType=SMALL, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/medium/celular-iphone-11-azul.png), MediaDTO(sizeType=LARGE, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/large/celular-iphone-11-azul.png), MediaDTO(sizeType=THUMBNAIL, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/thumbnail/celular-iphone-11-vermelho.png), MediaDTO(sizeType=SMALL, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/small/celular-iphone-11-vermelho.png), MediaDTO(sizeType=MEDIUM, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/medium/celular-iphone-11-vermelho.png), MediaDTO(sizeType=LARGE, liveloUrl=https://s3.sao01.cloud-object-storage.appdomain.cloud/catalog-media-storage/id-source/productId/skuseller2/large/celular-iphone-11-vermelho.png)]
I achieved filtering for one of the sizes. This works!
However, I could not figure out how can I filter over the 4 sizes and create 4 new lists of it.
If I fix some error another appears ... so I´m really stuck.
And by the way I´ve been searching for a solution on the internet and in the forum for a couple of days but did´nt find something that fits.
If someone might help, I´d really be grateful.
I was thinking about using a 'forEach' to filter but even like that, I could filter just one size.
Thanks in advance.
**This is what I got till now: **
public class ProcessProductDTO {
String processId;
OperationProcess operation;
String categoryId;
ProductDTO productDTO;
}
public class ProductDTO {
String id;
Boolean active;
String displayName;
String longDescription;
List<MediaDTO> medias;
List<AttributeDTO> attributes;
}
public class MediaDTO {
String sizeType;
String liveloUrl;
}
public Properties toOccProductPropertiesDTO(ProcessProductDTO processProductDTO) throws JsonProcessingException {
String pSpecs = convertAttributes(processProductDTO.getProductDTO().getAttributes());
//List<String> medias = convertMedias(processProductDTO.getProductDTO().getMedias());
return Properties.builder()
.id(processProductDTO.getProductDTO().getId()) .active(processProductDTO.getProductDTO().getActive())
.listPrices(new HashMap())
.p_specs(pSpecs)
//.medias(medias)
.displayName(processProductDTO.getProductDTO()
.getDisplayName())
.longDescription(processProductDTO.getProductDTO().getLongDescription())
.build(); }
private String convertAttributes(List<AttributeDTO> attributes) throws JsonProcessingException {
Map<String, String> attribs = attributes.stream()
.collect(Collectors.toMap(AttributeDTO::getName, AttributeDTO::getValue));
return objectMapper.writeValueAsString(attribs);
}
private List<MediaDTO> convertMedias(ProcessProductDTO processProduct, List<MediaDTO> mediaDTO){
List<MediaDTO> filteredList = processProduct.getProductDTO().getMedias();
Set<String> filterSet = mediaDTO.stream().map(MediaDTO::getSizeType).collect(Collectors.toSet());
return filteredList.stream().filter(url -> filterSet.contains("SMALL")).collect(Collectors.toList());
}
UPDATE
I got the following result:
private Properties toOccProductPropertiesDTO(ProcessProductDTO processProductDTO) throws JsonProcessingException {
String pSpecs = convertAttributes(processProductDTO.getProductDTO().getAttributes());
MediaOccDTO medias = convertMedias(processProductDTO.getProductDTO().getMedias());
return Properties.builder()
.id(processProductDTO.getProductDTO().getId())
.active(processProductDTO.getProductDTO().getActive())
.listPrices(new HashMap())
.p_specs(pSpecs)
.medias(medias)
.displayName(processProductDTO.getProductDTO().getDisplayName())
.longDescription(processProductDTO.getProductDTO().getLongDescription())
.build();
}
private MediaOccDTO convertMedias(List<MediaDTO> mediaDTOs){
String smallImageUrls = generateOccUrl(mediaDTOs, ImageSizeType.SMALL);
String mediumImageUrls = generateOccUrl(mediaDTOs, ImageSizeType.MEDIUM);
String largeImageUrls = generateOccUrl(mediaDTOs, ImageSizeType.LARGE);
String thumbImageUrls = generateOccUrl(mediaDTOs, ImageSizeType.THUMB);
return MediaOccDTO.builder()
.p_smallImageUrls(smallImageUrls)
.p_mediumImageUrls(mediumImageUrls)
.p_largeImageUrls(largeImageUrls)
.p_thumbImageUrls(thumbImageUrls)
.build();
}
private String generateOccUrl(List<MediaDTO> mediaDTOs, ImageSizeType imageSizeType){
return mediaDTOs.stream()
.filter(m -> m.getSizeType().equals(imageSizeType))
.map(MediaDTO::getLiveloUrl)
.reduce(",", String::concat);
}
The problem is:
the comparison: m.getSizeType().equals(imageSizeType)
is always false, so the list gets created empty...
Though the question is laborious, I could think of the requirement being, you need to create 4 new lists based on sizeType.
Stream collector, can collect the results to a single data structure. It can be a list, set, Map etc.
Since you need 4 lists based on sizeType, you will need to pass through the stream 4 times to create 4 lists.
Another Alternate will be to create a Map<SizeType, List<MediaDTO>>
This can be achieved through,
mediaDTO.stream().collect(Collectors.toMap(i -> i.getSizeType(), i->i)
I think the toMap doesn't collect the values in a list. We need groupingBy instead.
mediaDTO.stream()
.collect(Collectors.groupingBy(MediaDTO::getSizeType));
I am migrating my prototype from a listener to a visitor pattern. In the prototype, I have a grammar fragment like this:
thingList: thing+ ;
thing
: A aSpec # aRule
| B bSpec # bRule
;
Moving to a visitor pattern, I am not sure how I write visitThingList. Every visitor returns a specializes subclass of "Node", and I would love somehow when to be able to write something like this, say a "thingList" cares about the first thing in the list some how ...
visitThingList(cx: ThingListContext): ast.ThingList {
...
const firstThing = super.visit(cx.thing(0));
The problem with this is in typing. Each visit returns a specialized type which is a subclass of ast.Node. Because I am using super.visit, the return value will be the base class
of my node tree. However, I know because I am looking at the grammar
and because I wrote both vistARule and visitBRule that the result of the visit will be of type ast.Thing.
So we make visitThingList express it's expectation with cast ...
visitThingList(cx: ThingListContext): ast.ThingList {
const firstThing = super.visit(cx.thing(0));
if (!firstThing instanceof ast.Thing) {
throw "no matching visitor for thing";
}
// firstThing is now known to be of type ast.Thing
...
In much of my translator, type problems with ast Nodes are a compile time issue, I fix them in my editor. In this case, I am producing a more fragile walk, which will only reveal the fragility at runtime and then only with certain inputs.
I think I could change my grammar, to make it possible to encode the
type expectations of vistThingList() by creating a vistThing() entry point
thingList: thing+ ;
thing: aRule | bRule;
aRule: A aSpec;
bRule: B bSpec;
With vistThing() typed to match the expectation:
visitThing(cx: ThingContext): ast.Thing { }
visitThingList(cx: ThingListContext) {
const firstThing: ast.Thing = this.visitThing(cx.thing(0));
Now visitThingList can call this.visitThing() and the type enforcement of making sure all rules that a thing matches return ast.Thing belongs to visitThing(). If I do create a new rule for thing, the compiler will force me to change the return type of visitThing() and if I make it return something which is NOT a thing, visitThingList() will show type errors.
This also seems wrong though, because I don't feel like I should have to change my grammar in order to visit it.
I am new to ANTLR and wondering if there is a better pattern or approach to this.
When I was using the listener pattern, I wrote something like:
enterThing(cx: ThingContext) { }
enterARule(cx : ARuleContext) { }
enterBRule(cx : BRuleContext) { }
Not quite: for a labeled rule like thing, the listener will not contain enterThing(...) and exitThing(...) methods. Only the enter... and exit... methods for the labels aSpec and bSpec will be created.
How would I write the visitor walk without changing the grammar?
I don't understand why you need to change the grammar. When you keep the grammar like you mentioned:
thingList: thing+ ;
thing
: A aSpec # aRule
| B bSpec # bRule
;
then the following visitor could be used (again, there is no visitThing(...) method!):
public class TestVisitor extends TBaseVisitor<Object> {
#Override
public Object visitThingList(TParser.ThingListContext ctx) {
...
}
#Override
public Object visitARule(TParser.ARuleContext ctx) {
...
}
#Override
public Object visitBRule(TParser.BRuleContext ctx) {
...
}
#Override
public Object visitASpec(TParser.ASpecContext ctx) {
...
}
#Override
public Object visitBSpec(TParser.BSpecContext ctx) {
...
}
}
EDIT
I do not know how, as i iterate over that, to call the correct visitor for each element
You don't need to know. You can simply call the visitor's (super) visit(...) method and the correct method will be invoked:
class TestVisitor extends TBaseVisitor<Object> {
#Override
public Object visitThingList(TParser.ThingListContext ctx) {
for (TParser.ThingContext child : ctx.thing()) {
super.visit(child);
}
return null;
}
...
}
And you don't even need to implement all methods. The ones you don't implement, will have a default visitChildren(ctx) in them, causing (as the name suggests) all child nodes under them being traversed.
In your case, the following visitor will already cause the visitASpec and visitBSpec being invoked:
class TestVisitor extends TBaseVisitor<Object> {
#Override
public Object visitASpec(TParser.ASpecContext ctx) {
System.out.println("visitASpec");
return null;
}
#Override
public Object visitBSpec(TParser.BSpecContext ctx) {
System.out.println("visitBSpec");
return null;
}
}
You can test this (in Java) like this:
String source = "... your input here ...";
TLexer lexer = new TLexer(CharStreams.fromString(source));
TParser parser = new TParser(new CommonTokenStream(lexer));
TestVisitor visitor = new TestVisitor();
visitor.visit(parser.thingList());
I am using rxjava2 for the first time on an Android project, and am doing SQL queries on a background thread.
However I am having trouble figuring out the best way to do a simple SQL query, and being able to handle the case where the record may or may not exist. Here is the code I am using:
public Observable<Record> createRecordObservable(int id) {
Callable<Record> callback = new Callable<Record>() {
#Override
public Record call() throws Exception {
// do the actual sql stuff, e.g.
// select * from Record where id = ?
return record;
}
};
return Observable.fromCallable(callback).subscribeOn(Schedulers.computation());
}
This works well when there is a record present. But in the case of a non-existent record matching the id, it treats it like an error. Apparently this is because rxjava2 doesn't allow the Callable to return a null.
Obviously I don't really want this. An error should be only if the database failed or something, whereas a empty result is perfectly valid. I read somewhere that one possible solution is wrapping Record in a Java 8 Optional, but my project is not Java 8, and anyway that solution seems a bit ugly.
This is surely such a common, everyday task that I'm sure there must be a simple and easy solution, but I couldn't find one so far. What is the recommended pattern to use here?
Your use case seems appropriate for the RxJava2 new Observable type Maybe, which emit 1 or 0 items.
Maybe.fromCallable will treat returned null as no items emitted.
You can see this discussion regarding nulls with RxJava2, I guess that there is no many choices but using Optional alike in other cases where you need nulls/empty values.
Thanks to #yosriz, I have it working with Maybe. Since I can't put code in comments, I'll post a complete answer here:
Instead of Observable, use Maybe like this:
public Maybe<Record> lookupRecord(int id) {
Callable<Record> callback = new Callable<Record>() {
#Override
public Record call() throws Exception {
// do the actual sql stuff, e.g.
// select * from Record where id = ?
return record;
}
};
return Maybe.fromCallable(callback).subscribeOn(Schedulers.computation());
}
The good thing is the returned record is allowed to be null. To detect which situation occurred in the subscriber, the code is like this:
lookupRecord(id)
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<Record>() {
#Override
public void accept(Record r) {
// record was loaded OK
}
}, new Consumer<Throwable>() {
#Override
public void accept(Throwable throwable) {
// there was an error
}
}, new Action() {
#Override
public void run() {
// there was an empty result
}
});
I am using the XMLUnit in JUnit to compare the results of tests. I have a problem wherein there is an Element in my XML which gets the CURRENT TIMESTAMP as the tests run and when compared with the expected output, the results will never match.
To overcome this, I read about using org.xmlunit.diff.NodeFilters, but do not have any examples on how to implement this. The code snippet I have is as below,
final org.xmlunit.diff.Diff documentDiff = DiffBuilder
.compare(sourcExp)
.withTest(sourceActual)
.ignoreComments()
.ignoreWhitespace()
//.withNodeFilter(Node.ELEMENT_NODE)
.build();
return documentDiff.hasDifferences();
My problem is, how do I implement the NodeFilter? What parameter should be passed and should that be passed? There are no samples on this. The NodeFilter method gets Predicate<Node> as the IN parameter. What does Predicate<Node> mean?
Predicate is a functional interface with a single test method that - in the case of NodeFilter receives a DOM Node as argument and returns a boolean. javadoc of Predicate
An implementation of Predicate<Node> can be used to filter nodes for the difference engine and only those Nodes for which the Predicate returns true will be compared. javadoc of setNodeFilter, User-Guide
Assuming your element containing the timestamp was called timestamp you'd use something like
.withNodeFilter(new Predicate<Node>() {
#Override
public boolean test(Node n) {
return !(n instanceof Element &&
"timestamp".equals(Nodes.getQName(n).getLocalPart()));
}
})
or using lambdas
.withNodeFilter(n -> !(n instanceof Element &&
"timestamp".equals(Nodes.getQName(n).getLocalPart())))
This uses XMLUnit's org.xmlunit.util.Nodes to get the element name more easily.
The below code worked for me,
public final class IgnoreNamedElementsDifferenceListener implements
DifferenceListener {
private Set<String> blackList = new HashSet<String>();
public IgnoreNamedElementsDifferenceListener(String... elementNames) {
for (String name : elementNames) {
blackList.add(name);
}
}
public int differenceFound(Difference difference) {
if (difference.getId() == DifferenceConstants.TEXT_VALUE_ID) {
if (blackList.contains(difference.getControlNodeDetail().getNode()
.getParentNode().getNodeName())) {
return DifferenceListener.RETURN_IGNORE_DIFFERENCE_NODES_IDENTICAL;
}
}
return DifferenceListener.RETURN_ACCEPT_DIFFERENCE;
}
public void skippedComparison(Node node, Node node1) {
}
I have the following method:
#Override
public <T> T method(T object){
if(object instanceOf Type1){
...
}
elseif(object instanceOf Type2){
...
}
...
}
object is always of type SuperType and Type1, Type2, ... are all subtypes of SuperType. I don't have acces to any of the types SuperType, Type1, etc., so I cannot change them.
I´d like to eliminate this structure that has a lot of if-s and instanceOf checks. I tried implementing the Visitor pattern for this purpose, but it didn´t work, as I cannot modify any of the types mentioned above.
Does anyone know a nice solution for this example? Thank you!
You could have a dispatch table.
private final static Map<Class<?>, Handler> dispatch = ....
// contains things like Type2.class -> Type2Handler
dispatch.get(object.getClass()).handle(object);
// may need to iterate superclasses if that is a concern
Not sure if that is better, though.