I am looping through object layer and there are certain objects(Rectangle Map object in my case) I want to remove based on certain condition, but I don't see any method to do this.
there are two methods for your use case:
com.badlogic.gdx.maps.MapObjects#remove(com.badlogic.gdx.maps.MapObject)
com.badlogic.gdx.maps.MapObjects#remove(int)
See https://libgdx.badlogicgames.com/ci/nightlies/docs/api/com/badlogic/gdx/maps/MapObjects.html
So I guess you will do something like this:
ArrayList<MapObject> objectsToRemove = new ArrayList<>();
for (MapObject object : mapLayer.getObjects()) {
if (object.getName().contains("removeMe")) // TODO
{
objectsToRemove.add(object);
}
}
for (MapObject mapObject : objectsToRemove) {
mapLayer.getObjects().remove(mapObject);
}
Related
I'm building an app for a friend and I use Firestore. What I want is to display a list of favorite places but for some reason, the list is always empty.
I cannot get the data from Firestore. This is my code:
fun getListOfPlaces() : List<String> {
val places = ArrayList<String>()
placesRef.get().addOnCompleteListener { task ->
if (task.isSuccessful) {
for (document in task.result) {
val name = document.data["name"].toString()
places.add(name)
}
}
}
return list;
}
If I try to print, let's say the size of the list in onCreate function, the size is always 0.
Log.d("TAG", getListOfPlaces().size().toString()); // Is 0 !!!
I can confirm Firebase is successfully installed.
What am I missing?
This is a classic issue with asynchronous web APIs. You cannot return something now, that hasn't been loaded yet. With other words, you cannot simply return the places list as a result of a method because it will always be empty due the asynchronous behavior of the onComplete function. Depending on your connection speed and the state, it may take from a few hundred milliseconds to a few seconds before that data is available.
But not only Cloud Firestore loads data asynchronously, almost all of modern other web APIs do, since it may take some time to get the data. But let's take an quick example, by placing a few log statements in the code, to see more clearly what I'm talking about.
fun getListOfPlaces() : List<String> {
Log.d("TAG", "Before attaching the listener!");
val places = ArrayList<String>()
placesRef.get().addOnCompleteListener { task ->
if (task.isSuccessful) {
Log.d("TAG", "Inside onComplete function!");
for (document in task.result) {
val name = document.data["name"].toString()
places.add(name)
}
}
}
Log.d("TAG", "After attaching the listener!");
return list;
}
If we run this code will, the output in your logcat will be:
Before attaching the listener!
After attaching the listener!
Inside onComplete function!
This is probably not what you expected, but it explains precisely why your places list is empty when returning it.
The initial response for most developers is to try and "fix" this asynchronous behavior, which I personally recommend against it. Here is an excelent article written by Doug Stevenson that I'll highly recommend you to read.
A quick solve for this problem would be to use the places list only inside the onComplete function:
fun readData() {
placesRef.get().addOnCompleteListener { task ->
if (task.isSuccessful) {
val list = ArrayList<String>()
for (document in task.result) {
val name = document.data["name"].toString()
list.add(name)
}
//Do what you need to do with your list
}
}
}
If you want to use the list outside, there is another approach. You need to create your own callback to wait for Firestore to return you the data. To achieve this, first you need to create an interface like this:
interface MyCallback {
fun onCallback(value: List<String>)
}
Then you need to create a function that is actually getting the data from the database. This method should look like this:
fun readData(myCallback : MyCallback) {
placesRef.get().addOnCompleteListener { task ->
if (task.isSuccessful) {
val list = ArrayList<String>()
for (document in task.result) {
val name = document.data["name"].toString()
list.add(name)
}
myCallback.onCallback(list)
}
}
}
See, we don't have any return type anymore. In the end just simply call readData() function in your onCreate function and pass an instance of the MyCallback interface as an argument like this:
readData(object: MyCallback {
override fun onCallback(value: List<String>) {
Log.d("TAG", list.size.toString())
}
})
If you are using Kotlin, please check the other answer.
Nowadays, Kotlin provides a simpler way to achieve the same result as in the case of using a callback. This answer is going to explain how to use Kotlin Coroutines. In order to make it work, we need to add the following dependency in our build.gradle file:
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-play-services:1.2.1"
This library that we use is called Module kotlinx-coroutines-play-services and is used for the exact same purpose. As we already know, there is no way we can return a list of objects as a result of a method because get() returns immediately, while the callback from the Task it returns will be called sometime later. That's the reason why we should wait until the data is available.
When calling "get()" on the Task object that is returned, we can attach a listener so we can get the result of our query. What we need to do now is to convert this into something that is working with Kotlin Coroutines. For that, we need to create a suspend function that looks like this:
private suspend fun getListOfPlaces(): List<DocumentSnapshot> {
val snapshot = placesRef.get().await()
return snapshot.documents
}
As you can see, we have now an extension function called await() that will interrupt the Coroutine until the data from the database is available and then return it. Now we can simply call it from another suspend method like in the following lines of code:
private suspend fun getDataFromFirestore() {
try {
val listOfPlaces = getListOfPlaces()
} catch (e: Exception) {
Log.d(TAG, e.getMessage()) //Don't ignore potential errors!
}
}
The reason for having a empty list got perfectly answered by Alex Mamo above.
I just like to present the same thing without needing to add an extra interface.
In Kotlin you could just implement it like so:
fun readData(myCallback: (List<String>) -> Unit) {
placesRef.get().addOnCompleteListener { task ->
if (task.isSuccessful) {
val list = ArrayList<String>()
for (document in task.result) {
val name = document.data["name"].toString()
list.add(name)
}
myCallback(list)
}
}
}
and then use it like so:
readData() {
Log.d("TAG", it.size.toString())
})
I am trying to cast my http.get response to actual object -> in my specific case array of complex objects.
In a normal scenario, where you don't need any specific casting, you could do the following (simplified):
return this.httpClient.get(api, this._options_get)
.pipe(
map((response: any) => {
return response.value as NewProduct[];
})
);
As my need is to actually cast this to an object, I have created this static method which does that:
static toProduct(otherProduct: any): NewProduct {
let item = new NewProduct();
Object.keys(otherProduct).forEach(prop => {
if (typeof otherProduct[prop] === "object" && otherProduct[prop]) {
if (!item.hasOwnProperty(prop))
item[prop] = otherProduct[prop];
Object.assign(item[prop], otherProduct[prop]);
}
else
item[prop] = otherProduct[prop];
})
return item;
}
Under Object.assign I am taking already existing object which was initialized under first line and I am simply copying all the properties from the otherProduct to it. However I start to face problem when it comes to array of objects. Example (with simplified class):
export class Person {
name:string;
age:number;
addresses:Address[] = [];
}
export class Address {
street:string;
city:string;
fullAddress() : string { return this.street + this.city; }
}
As soon as I have this sort of array, I don't have any initial object in item. This means that there is no initial constructor of a class which results in simple Object. This is no error for JavaScript or TypeScript; however when I am trying to access internal method of a class (in our simplified case fullAddress(), I won't be able to.
The reason why I need that is that I am overriding toString() method on my sub-classes, which is necessary for MatTableDataSource when you use the filter method (which works with strings).
Is there a way how to retrieve elements from http.get() and properly map results to typed objects?
You're being too generic. You're creating objects of objects, not objects of Product with children of Addresses.
If you want to create a new product you're going to have to understand the relationship between the api's results and the data you want in the UI.
Because you're using classes and not interfaces and want to inherit the functions, the only way to get new Addresses into the new object is with the new keyword.
And you'll have to loop through. You're not going to find a shortcut for this. You're going to need to loop through the data and transform it. If your api is giving you an ApiPerson then you'll want to do something like this:
const addresses = apiPerson.addresses.map((apiAddress) => {
const address = new Address();
// map properties of apiAddress to address...
return address;
});
Now that you have the addresses, you can map the apiPerson to a new Person()'s properties and then set the newPerson.addresses = address.
I have a Spring API that allows the user to specify the JsonView of each call using a view param like so:
/api/v1/person/1?view=viewName
I then use Spring's MappingJacksonValue to set the correct view dynamically instead of using #JsonView() annotation and finally I just return the MappingJacksonValue instance which produces something along the lines of
[
{ id: 1 },
{ id: 2 }
]
I can't for the life of me figure out how to easily wrap my MappingJacksonValue instances in an ObjectNode so that I can change all API results from the snippet above to this
{
"data" : [
{ id: 1 },
{ id: 2 }
]
}
I tried using a regular HashMap<> but that didn't work - the serialization completely ignores the MappingJacksonValue view and it also produces Map-specific results
{
data: {
value: [],
serializationView: "com.blah.models.view.View$Id",
filters: null,
jsonpFunction: null
}
}
So can someone pls let me know what's the best way to achieve result wrapping in my scenario?
Thanks in advance!
If anyone comes across this post looking to do the same thing, I realized I was looking at the problem in the wrong way. I ended up creating a ServiceResponse class and wrapped up the object in there like so
public class ServiceResponse {
#JsonView(View.Id.class)
private Object data;
public ServiceResponse (Object data) {
this.data = data;
}
}
So essentially instead of returning new MappingJacksonValue(someReturnObject) I'm returning new MappingJacksonValue(new ServiceResponse(someReturnObject)). This way everything is wrapped nicely in a data JSON object and the setSerializationView method still filters my objects properly.
Hope this helps someone.
I would like to change the way enums are marshalled to JSON. I am currently using default grails.converters.JSON ( as JSON) and for example in controller I use:
FilmKind.values() as JSON
The output of this is:
"kind":[{"enumType":"FilmKind","name":"DRAMA"},{"enumType":"FilmKind","name":"ACTION"}]
I would like to remove "enumType" and just return:
"kind":["DRAMA","ACTION"]
I am looking for a solution which would still allow me to use
as JSON
because I don't want to marshall each enumeration individually.
In case anyone is wandering how to convert all enum values to plain String values in a generic way:
class EnumTypeHidingJSONMarshaller {
void register() {
JSON.registerObjectMarshaller(Enum) { Enum someEnum ->
someEnum.toString()
}
}
}
because I don't want to marshall each enumeration individually.
Well, unless you want to write your own JSON converter, marshalling is the best approach here. Reason is because the only real other way is to do what Sergio is suggesting and you'll have to call that code everywhere you need it. And if FilmKind is a property of another class then his solution won't work at all really.
I would suggest Marshallers and here is how I would do it. Create a class called FilmKindMarsaller:
class FilmKindMarshaller {
void register() {
JSON.registerObjectMarshaller(FilmKind) { FilmKind filmKind ->
[
name: filmKind.toString()
]
}
}
}
Then add the following to your Bootstrap:
[ new FilmKindMarshaller() ].each { it.register() }
The above is so that you can just keep adding instances of each Marshaller you need.
Now, anytime FilmKind is JSON'ified, be that on its own or part of a parent class, you get the JSON you want, sans enumType.
You can register a custom object marshaller for your domain class to allow as JSON. In your Bootstrap.groovy, you can do something like this:
JSON.registerObjectMarshaller(FilmKind) {
def result = [:]
def props = ['name']
props.each { prop ->
result[prop] = it."$prop"
}
result
}
How about:
def display = [kind:[]]
FilmKind.values().each { val ->
display.kind.add(val.value)
}
render display as JSON
EDIT: onload() method changed to afterLoad(): Otherwise objects might not be passed properly to the map.
I am currently using some domain classes with a lot of dynamic, complex properties, that I need to persist and update regularly.
I keep these in a Map structure for each class since this makes it easy for referencing in my controllers etc.
However, since Grails does not seem to be able to persist complex property types like List and Map in the DB I am using the following approach to achieve this via JSON String objects:
class ClassWithComplexProperties {
Map complexMapStructure //not persisted
String complexMapStructureAsJSON //updated and synched with map via onload,beforeInsert,beforeUpdate
static transients = ['complexMapStructure']
def afterLoad() { //was previously (wrong!): def onLoad() {
complexMapStructure=JSON.parse(complexMapStructureAsJSON)
}
def beforeInsert() {
complexMapStructureAsJSON= complexMapStructure as JSON
}
def beforeUpdate() {
complexMapStructureAsJSON= complexMapStructure as JSON
}
static constraints = {
complexMapStructureAsJSON( maxSize:20000)
}
}
This works well as long I am only loading data from the DB, but I run into trouble when I want to save back my changes to the DB. E.g. when I do the following
/* 1. Load the json String, e.g. complexMapStructureAsJSON="""{
data1:[[1,2],[3,4]],//A complex structure of nested integer lists
data1:[[5,6]] //Another one
}""" :
*/
ClassWithComplexProperties c=ClassWithComplexProperties.get(1)
// 2. Change a value deep in the map:
c.complexMapStructure.data1[0][0]=7
// 3. Try to save:
c.save(flush:true)
This will usually not work, since, I guess(?), GORM will ignore the save() request due to the fact that the map itself is transient, and no changes are found in the persisted properties.
I can make it work as intended if I hack step 3 above and change it to:
// 3.Alternative save:
complexMapStructureAsJSON="" //creating a change in persisted property (which will be overwritten anyway by the beforeUpdate closure)
c.save(flush:true)
To me this is not a very elegant handling of my problem.
The questions:
Is there a simpler approach to persist my complex, dynamic map data?
If I need to do it the way I currently do, is there a way to avoid the hack in step 3 ?
For option 2, you can use the beforeValidate event instead of beforeInsert and beforeUpdate events to ensure that the change propagates correctly.
class ClassWithComplexProperties {
Map complexMapStructure //not persisted
String complexMapStructureAsJSON //updated and synched with map via onload,beforeInsert,beforeUpdate
static transients = ['complexMapStructure']
def onLoad() {
complexMapStructure=JSON.parse(complexMapStructureAsJSON)
}
// >>>>>>>>>>>>>>
def beforeValidate() {
complexMapStructureAsJSON= complexMapStructure as JSON
}
// >>>>>>>>>>>>>>
static constraints = {
complexMapStructureAsJSON( maxSize:20000)
}
}
I of course do not know much about the application you are building, but it won't hurt to look up alternate data storage models particularly NOSQL databases. Grails has got some support for them too.
Is there a simpler approach to persist my complex, dynamic map data?
Grails can persist List and Map out of the box, you don't need to write complex conversion code and abuse Json.
Example for Map:
class ClassWithComplexProperties {
Map<String, String> properties
}
def props = new ClassWithComplexProperties()
props.properties = ["foo" : "bar"]
props.save()
Example for List:
class ClassWithComplexProperties {
List<String> properties
static hasMany = [properties: String]
}
def props = new ClassWithComplexProperties()
props.properties = ["foo", "bar"]
props.save()
I think this is much easier and cleaner way how to deal with it.
In response to
Is there a simpler approach to persist my complex, dynamic map data?
Grails can persist Sets, Lists and Maps to the database. That may be a simpler approach than dealing with JSON conversions. To have the map persisted to the database you need to include it in the hasMany property.
Map complexMapStructure
static hasMany = [complexMapStructure: dynamicComplexPropertyObject]
The documentation suggests that using a Bag may be more efficient.