I working on a flutter project. I want to pass list from one page to another page. but it not working out for me
List list;
articleCall save = await Navigator.of(context).push(new MaterialPageRoute<articleCall>(
builder: (BuildContext context) {
return new AddArticleDialog(list);
},
-----------
class AddArticleDialog extends StatefulWidget {
List ls=[];
AddArticleDialog({this.ls});
#override
AddArticleDialogState createState() => new AddArticleDialogState();
}
It says me the error: Too many positional arguments: 0 expected, but 1 found. Please help
Thanks,
Sathish
When braces {} are used on constructor parameters, it will become named parameters as mentioned in the docs.
Having the constructor as
List? ls=[]; // List should be nullable since the argument is optional
AddArticleDialog({this.ls});
will require it to use an identifier for the argument.
return AddArticleDialog(ls: list);
Related
Ive got a function named allAppointmentList to get Appointments from the server using a GET method in AppointmentProvider class.
In my MyAppointments class I have initialized 2 lists named as appointment and allAppointments as below,
class _MyAppointmentState extends State<MyAppointment> {
bool isLoading = true;
List<Appointment> allAppointments=[];
List<Appointment> appointments = [];
And in the init state I have assigned the data I get from the allAppointmentList method to the 2 lists mentioned above.
#override
void initState() {
super.initState();
_loadAppointments();
}
_loadAppointments() async {
final AppointmentProvider appointmentProvider =
Provider.of<AppointmentProvider>(context, listen: false);
await appointmentProvider.getAllAppointments();
setState(() {
isLoading = false;
appointments = appointmentProvider.allAppointmentList;
allAppointments = appointmentProvider.allAppointmentList;
});
}
when I change one list the other changes as well.For example,
if I clear the appointments list,allAppoitments list gets cleared as well.If I remove the element in the second index of the appointments list,the element in the second index of the allAppointments list gets removed as well.
How can I make these two list act independently ?
Your problem is probably that you think this creates new lists:
appointments = appointmentProvider.allAppointmentList;
allAppointments = appointmentProvider.allAppointmentList;
My guess is that appointmentProvider.allAppointmentList returns the same List instance every time which is a problem here since you are then just assigning the same List object to both appointments and allAppointments.
I am not sure if you also want copies of all the objects inside the lists but if you just want to have independent lists which then contains references to the same objects, the safest would just be to do:
appointments = appointmentProvider.allAppointmentList.toList();
allAppointments = appointmentProvider.allAppointmentList.toList();
This will create new lists which then contains the same objects from appointmentProvider.allAppointmentList. But you can then delete/add elements to each of these lists without this change also happening to the other lists.
appointments and allAppointments are currently just references to appointmentProvider.allAppointmentList. You can create new instances as follows:
appointments = [...appointmentProvider.allAppointmentList];
allAppointments = [...appointmentProvider.allAppointmentList];
This uses a list literal [] in combination with the spread operator ... to create a new list with the same elements. Note that the elements themselves are still references to their original instances and are not deep copies.
I want to use a list in another class. So my idea was to simply use a constructor, but i got a few problems. First of all i want to use the list for a PaginatedDataTable. Therefore I created a new class for the datasource and i want to use my list of DataRows in this class. Here is my constructor to get access to the list:
class ExerciseDataSource extends DataTableSource {
ExerciseDataSource({Key key, this.list}) : super(key: key);
final List<DataRow> list;
I got an error for using the key, saying 'The named parameter 'key' isn't defined.'
I also got an error in my class, where i have my list of DataRows named _rowList with the error 'The instance member '_rowList' can't be accessed in an initializer.':
class _ExerciseTableState extends State<ExerciseTable> {
final ExerciseDataSource _rowsDataSource = ExerciseDataSource(list: _rowList);```
If you look at the definition of DataTableSource you will notice it extends aChangeNotifier, not a Widget.
You can't use a property of the class as a property of another property. You could modify your code to something like this:
class __ExerciseTableState extends State<_ExerciseTable> {
final List _rowList = [];
ExerciseDataSource _rowsDataSource;
#override
void initState() {
_rowsDataSource = ExerciseDataSource(list: _rowList);
super.initState();
}
#override
Widget build(BuildContext context) {
return Container();
}
}
I am trying to embed collection of Tag forms to Service form, according to this tutorial. Tag and Service entities have many-to-many relationship.
Form is rendering correctly. But when I submit form, I get
Could not determine access type for property "tagList"
error. I don't understand why new Tag object is not added to the Service class by calling the addTag() method.
ServiceType
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('title', TextType::class, array(
'label' => 'Title'
))
;
$builder->add('tagList', CollectionType::class, array(
'entry_type' => TagType::class,
'allow_add' => true,
'allow_delete' => true,
'by_reference' => false
)));
}
Service class
{
....
/**
* #ORM\ManyToMany(targetEntity="Tag", mappedBy="serviceList",cascade={"persist"})
*/
private $tagList;
/**
* #return ArrayCollection
*/
public function getTagList()
{
return $this->tagList;
}
/**
* #param Tag $tag
* #return Service
*/
public function addTag(Tag $tag)
{
if ($this->tagList->contains($tag) == false) {
$this->tagList->add($tag);
$tag->addService($this);
}
}
/**
* #param Tag $tag
* #return Service
*/
public function removeTag(Tag $tag)
{
if ($this->tagList->contains($tag)) {
$this->tagList->removeElement($tag);
$tag->removeService($this);
}
return $this;
}
}
Tag class
{
/**
* #ORM\ManyToMany(targetEntity="Service", inversedBy="tagList")
* #ORM\JoinTable(name="tags_services")
*/
private $serviceList;
/**
* #param Service $service
* #return Tag
*/
public function addService(Service $service)
{
if ($this->serviceList->contains($service) == false) {
$this->serviceList->add($service);
$service->addTag($this);
}
return $this;
}
/**
* #param Service $service
* #return Tag
*/
public function removeService(Service $service)
{
if ($this->serviceList->contains($service)) {
$this->serviceList->removeElement($service);
$service->removeTag($this);
}
return $this;
}
}
ServiceController
public function newAction(Request $request)
{
$service = new Service();
$form = $this->createForm('AppBundle\Form\ServiceType', $service);
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
$em = $this->getDoctrine()->getManager();
$em->persist($service);
$em->flush();
return $this->redirectToRoute('service_show', array('id' => $service->getId()));
}
return $this->render('AppBundle:Service:new.html.twig', array(
'service' => $service,
'form' => $form->createView(),
));
}
Could you please try to implement code from this URL?
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/association-mapping.html#owning-and-inverse-side-on-a-manytomany-association
First, please try to change mapped/inverse sides, and remove $service->addTag($this); from Tag::addService method.
Short version:
I just ran into this problem and solved it by adding a setter for the affected property:
Could not determine access type for property "tagList"
public function setTagList(Array $tagList)
{
$this->tagList = $tagList;
}
Long version:
The error message is signaling that Symfony is trying to modify the object's state, but cannot figure out how to actually make the change due to the way its class is set up.
Taking a look at Symfony's internals, we can see that Symfony gives you 5 chances to give it access and picks the best one in this order from top to bottom:
A setter method named setProperty() with one argument:
This is the first thing Symfony checks for and is the most explicit way to achieve this. As far as I'm aware this is the best practice:
class Entity {
protected $tagList;
//...
public function getTagList()
{
return $this->tagList;
}
//...
}
A combined getter and setter in one method with one argument:
It's important to realize that this method will also be accessed by Symfony in order to get the object's state. Since those method calls don't include an argument, the argument in this method must be optional.
class Entity {
protected $tagList;
//...
public function tagList($tags = null)
{
if($reps){
$this->tagList = $tags;
} else {
return $this->tagList;
}
}
//...
}
The affected property being declared as public:
class Entity {
public $tagList;
//... other properties here
}
A __set magic method:
This will affect all properties rather than just the one you intended.
class Entity {
public $tagList;
//...
public function __set($name, $value){
$this->$name = $value;
}
//...
}
A __call magic method (in some cases):
I wasn't able to confirm this, but the internal code suggests this is possible when magic is enabled on PropertyAccessor's construction.
Only using one of the above strategies is required.
Maybe the problem is that Symfony can't access that property?
If you look at where that exception is thrown (writeProperty method in the PropertyAccessor class) it says it can be thrown:
If the property does not exist or is not public.
In the tutorial you mentioned it has property $tags, and method addTag. I'm just guessing here, but maybe there's a convention where it tries to call a method names add($singularForm) and this is failing for you because the property is tagList and the method is addTag.
I'm not 100% sure, but you could try debugging by setting a stop point in that Symfony method to see why it's being thrown.
Maybe you forgot in the __construct() of Service class and Tag class to initialize $tagList and $serviceList like this ?
$this->tagList = new ArrayCollection();
$this->serviceList = new ArrayCollection();
This seems like an error with your constructor. Try this :
public function __construct()
{
$this-> tagList = new \Doctrine\Common\Collections\ArrayCollection();
}
It's a long shot, but looking at your annotations I think the problem might be related to your manyToMany relationship. Try to change the owning side and inverse side (Swap the relationship) unless you specifically need to update from both ends (In that case I think the only solution is to add the objects manually or use oneToMany relationships).
Changes made only to the inverse side of an association are ignored.
Make sure to update both sides of a bidirectional association (or at
least the owning side, from Doctrine’s point of view)
This is a problem related to Doctrine I have suffered before, see:
http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/unitofwork-associations.html
Based on Symfony 3.3.10
I actually faced this problem many and many times, finally once i discovered where this problem was coming from, depending on the name you give to your entity property it can happen that the adder and the remover for your collection property aren't exactly what you are expecting.
Example: Your entity properity name is "foo" and you would expect the adder to be called "addFoo" and remover "removeFoo", but then all of a sudden the "Could not determine access type for property" appear.
So you start going into fear searching for w/e problems in your code, instead you just have to look this file inside Symfony core files:
vendor/symfony/symfony/src/Symfony/Component/PropertyAccess/PropertyAccessor.php
Inside this file there's a method called findAdderAndRemover.
Go there with your debugger and you will eventually find out that symfony searches for weird name for your adder/remover, they may actually end with "um" or "on" or "us" depending on the language (human language) you used to name them. Since i'm Italian this happen quite often.
Watch out for that, since the fix may be as simple as changing the name used for your add/remove method inside your entity to make them match with what Symfony core is looking for.
This happens to me when i use bin/console doctrine:generate:entities to create the methods automatically for me
If you are using symfony, and use EntityRepository instead of CollectionType, make sure you use the 'multiple' => true, on your form build, otherwise the input will be for one entity and not for many, therefore it will call the setTagList instead of using the methods addTagList and removeTagList.
I have clients passing in IDs like this: /v1/path?id=1,2,3
What I have and want
I have a resource class for Dropwizard/Jersey.
I'd like to show up the query-parameter id=1,2,3 as a List parameter in my resource's GET method
// Resource class
public List<Something> getFilteredList(#QueryParam("id") List<String> ids) {
// filter the List<Something> based on a list of ids
}
Right now, the ids list contains 1 string which is "1,2,3".
What I tried
I tried a filter but the query parameters given by Jersey's
ContainerRequestContext.getUriInfo().getQueryParameters()
is immutable.
Questions
I would like to apply a filter and change any comma separated query parameters into multi-valued parameters so that the resource method gets a list instead.
Is there a way to change the existing query parameters using a Jersey filter?
What's a good way to solve this problem?
The best way I can think of is to just create a wrapper class for the list. This makes it easier to take advantage of the specified functionality of Jersey. You can see what I mean at Passing custom type query parameter.
For example
public class IdFilter {
private List<String> ids = new ArrayList<>();
public List<String> getIds() { return ids; }
public static IdFilter valueOf(String param) {
IdFilter filter = new IdFilter();
for (String id: param.split(",") {
filter.getIds().add(id);
}
}
}
getFilteredList(#QueryParam("id") IdFilter ids) {
We don't need to do anything else. Just having the static valueOf is enough for Jersey to know how to parse the query string.
3 ways to solve it:
use the generic context-parameter UriInfo , which is not very expressive
add an explicit custom type that can parse a comma-separated list
stay with #QueryParam List<String> requiring a concatenated query like ?id=1&id=2&id=3 given as URI
I would prefer the second as most-expressive, like answered already by Paul. This way you can concisely pass a single CSV like ?id=1,2,3,3 and also use a Set to ensure unique ID values, e.g. resulting in only [1, 2, 3].
Generic context-param UriInfo
One way would be to use a generic parameter #Context UriInfo to get the list in the method's body:
public List<Something> getFilteredList( #Context UriInfo uriInfo ) {
List<String> idList = uriInfo.getQueryParameters().get("id"); // before was #QueryParam("id")
System.out.println("idList: " + idList);
// filter a given list by ids
var somethingFiltered = getSomethingList().stream()
.filter(s -> idList.contains(s.getId()))
.collect(toList());
return Response.status(Status.OK).entity(somethingFiltered).build();
}
See the tutorial in Java Vogue(2015): QueryParam Annotation In Jersey -
Custom type with static valueOf(String) factory-method
The other way is to design a custom type which can be constructed using a String:
class IdSet {
Set<String> values;
// a factory method, can also be named valueOf
public static IdSet fromString(String commaSeparated) {
return new HashSet( Arrays.asList( commaSeparated.split(",") ) );
}
}
public List<Something> getFilteredList(#QueryParam("id") IdSet ids) {
System.out.println("ids (Set): " + ids.values);
// filter a given list by ids
var somethingFiltered = getSomethingList().stream()
.filter(s -> ids.values.contains(s.getId()))
.collect(toList());
return Response.status(Status.OK).entity(somethingFiltered).build();
}
See Jersey's JavaDocs for #QueryParam:
The type T of the annotated parameter, field or property must either:
Be a primitive type
Have a constructor that accepts a single String argument
Have a static method named valueOf or fromString that accepts a single String argument (see, for example, Integer.valueOf(String))
Have a registered implementation of ParamConverterProvider that returns a ParamConverter instance capable of a "from string" conversion for the type.
Be List<T>, Set<T> or SortedSet<T>, where T satisfies 2, 3 or 4 above. The resulting collection is read-only.
Use a collection interface with multiple key-value pairs
When the calling client uses following URI pattern: /something?id=1&id=2&id=3 then JAX-RS can deserialize them to a single parameter of List<String> id having given multiple elements:
public List<Something> getFilteredList(#QueryParam("id") List<String> ids) {
System.out.println("ids : "+ids);
// filter a given list by ids
var somethingFiltered = getSomethingList().stream()
.filter(s -> ids.contains(s.getId()))
.collect(toList());
return Response.status(Status.OK).entity(somethingFiltered).build();
}
See Mkyong: JAX-RS #QueryParam example where explained the multiple occurrences of orderBy in the GET query:
#QueryParam will convert the query parameter “orderBy=age&orderBy=name” into java.util.List automatically.
See also
Handling Multiple Query Parameters in Jersey
Deserializing List<Map<String, String>> QueryParam in jersey 1
Jersey, #QueryParam List<String>
I have this code
var list = ['arg1=val1', 'arg2=val2', 'arg3=val3'];
var nlist = new List();
list.forEach( (e) {
nlist.addAll(e.split('='));
});
print(nlist);
addAll needs an argument is Iterable. But in this case, e.split() return List, not Iterable.
So why i can do that?
List implements Iterable and therefore is an Iterable (see https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:core.List just below the title)