When I define a spinner in ScalaJS and handle the spin value I am not able to get the new spin value in the event as I would have expected. According to the JQuery UI documentation the second parameter to the spin event is the ui object that contains a value attribute. So I defined a trait:
trait Number extends js.Object {
val value: Int = js.native
}
And then handle my spin event thus:
jQuery("#mySpinner").spinner(js.Dynamic.literal(spin = { (e: HTMLInputElement, ui: Number) =>
log("Change: " + ui.value)
}: js.ThisFunction1[HTMLInputElement, Number, Any]))
But the "value" attribute does not seem to be a member of the ui object as I get the exception below in my log statement. Can someone tell me what I am doing wrong?
uncaught exception: scala.scalajs.runtime.UndefinedBehaviorError: An
undefined behavior was detected: undefined is not an instance of
java.lang.Integer
You say e: HTMLInputElement but it should be e: Event
I suspect the problem is a combination of the previous comments. You are correct that, since you're using ThisFunction, the first element should be an Element of some sort. (Although, is it really an HTMLInputElement? That's a slightly unusual element type to put a spinner on.)
But that Element gets prepended to the function parameters, whereas you've got it replacing one.
In other words, you have
(e: HTMLInputElement, ui: Number)
but it needs to be
(elem: HTMLInputElement, e:Event, ui: Number)
in order to match the expected signature. So in practice, the system is trying to cast the value member of an Event, which of course doesn't exist, to Integer. It finds that value is undefined, tries to cast it to Integer, and boom.
I can't say I'm 100% certain (and IMO that ui parameter is just plain weird to begin with -- I'm a little suspicious of the jQueryUI documentation there), but that's my guess. Try fixing the signature of your call, and see if the error goes away...
Related
I switched to sound null safety and started getting runtime error in a simple assignment, that should never happen with sound null safety:
final widgetOnPressed = widget.onPressed;
Error:
type '(LogData) => void' is not a subtype of type '((LogData?) => void)?'
I can repro it for Flutter versions 2.12.0-4.1.pre and 2.13.0-0.0.pre.505.
PR: https://github.com/flutter/devtools/pull/3971
Failing line: https://github.com/flutter/devtools/blob/9fc560ff2e6749459e2ca6a1dc00bf6fb16ed93b/packages/devtools_app/lib/src/shared/table.dart#L1184
To repro, start DevTools at this PR for macos, connect to an app and click the tab 'Logging'. DevTools will show red screen and error in console.
Is it dart bug or the app bug? If it is the app bug, how can I debug it?
It's a bug in your code.
You didn't say which kind of error you got - a compile-time error or a runtime error. I'm guessing runtime error. (Well, you did say to launch it in the debugger, so that is a good hint too.)
The line final widgetOnPressed = widget.onPressed; looks like it can't possibly fail. After all, the type of the local variable is inferred from the expression assigned to it, and the runtime value of that expression will surely be a subtype of the static type because the type system is sound!
Isn't it? ISN'T IT?
It's not, sorry. Dart 2's type system is mostly sound, even more so with null safety, but class generics is covariant, which can still be unsound. It's fairly hard to hit one of the cases where that unsoundness shows its ugly head, but returning a function where the argument type is the class's type variable is one.
Your state class extends State<TableRow<T?>>, so the widget getter returns a TableRow<T?>. The onPressed of that type has type ItemCallback<T?>?, aka, void Function(T?)?.
You create a _TableRowState<LogData>, with its widget which has static type TableRow<LogData?>, but you somehow manage to pass it a TableRow<LogData> instead. That's fine. Class generics are covariant, so all is apparently fine at compile-time.
Then you do final widgetOnPressed = widget.onPressed;.
The static type of widgetOnPressed is void Function(LogData?) here.
The actual runtime type of onPressed is void Function(LogData) because it's from a TableRow<LogData>.
A void Function(LogData) is-not-a void Function(LogData?) because the former cannot be used in all places where the latter can (in particular, it can't be used in a place where it's called with null).
This assignment is potentially unsound, and actually unsound in this case. The compiler knows this and inserts an extra check to ensure that you don't assign a value to the variable which isn't actually valid. That check triggers and throws the error you see.
How do you avoid that?
Don't create a TableRow<LogData> where a TableRow<LogData?> is required.
Or type the variable as:
final ItemCallback<T>? widgetOnPressed = widget.onPressed;
(no ? on the T).
Or rewrite everything to avoid returning a function with a covariant type parameter (from the class) occurring contra-variantly (as an argument type).
Which solution fits you depends on what you want to be able to do.
I have nested comments. In order to fetch them from JSON, I have the following fromJson() function:
Comment.fromJson(Map<String, dynamic> json)
: id = json['id'],
...
children = json['children'] != null
? json['children'].map((c) => Comment.fromJson(c)).toList()
: null,
...
This checks if the current comment has any children comments, and if so, recursively parses them from JSON into a Comment. However when I run this, I get the following error:
[ERROR:flutter/shell/common/shell.cc(214)]
Dart Unhandled Exception:
type 'List<dynamic>' is not a subtype of type 'List<Comment>'
stack trace: #0 new Comment.fromJson (package:app/models/comment.dart:43:18)
Which points to the line where I assign children with children = json.... I'm new to dart, but I don't understand how mapping over a list, and returning a Comment doesn't let Dart infer the type of the list. How do I fix this? Adding as List<Comment> after toList() didn't work. If I add as Comment after Comment.fromJson(c), I get unnecessary cast.
Dart can't infer anything from json['children'].map(...).toList() because json['children'] is of type dynamic, and therefore it doesn't know what the .map call is going to resolve to at runtime.
At runtime, since .map is called without an explicit type, it ends up being a call to .map<dynamic>(...), and then .toList() returns List<dynamic>.
Try either:
Explicitly using .map<Comment>(...).
Casting json['children']: (json['children'] as List<Map<String, dynamic>>).map(...). It'd probably be a good idea to validate this anyway.
I am making use of MarkLogic's ability to call XQuery functions in the XSL transform.
Let's say I have an XQuery library with a function whose signature looks like the following. This is for illustrative purposes only.
declare function my-func:ex-join($first as xs:string, $last as xs:string) as xs:string
{
fn:concat($first, '-', $last)
}
From XQuery, I can call this function with empty sequence as parameters, with no issues, i.e.
ex-join((), '1244')
The function will just return an empty sequence, but I don't get any errors. If I try to all this function from with in my XSL transform,as in:
<xsl:value-of select="my-func:ex-join(//node/value/text(), 'something')"/>
If the /node/value does not exist, and an empty sequence is passed in, I get the coercion error.
Does anyone have suggestions to work around the coercion problem, outside of checking the values in XSL prior to the select? These are auto-generated XSL templates, which would mean a lot of coded checks.
Thanks,
-tj
Attempts to invoke that function in XQuery would fail too. It is probably due to function mapping that you don't notice this though. Put the following at the top of your XQuery code:
declare option xdmp:mapping "false";
Next to this, you only need to change the signature of your function to accept empty-sequences. Replace as xs:string with as xs:string?:
declare function my-func:ex-join($first as xs:string?, $last as xs:string?) as xs:string
fn:concat will accept empty sequences as arguments, so no further changes required to make it work..
HTH!
In Darts API, the method
element.setCustomValidity(num message)
has a number as the argument. I was expecting the type of the message to be a String. Is this an error?
I created an issue https://github.com/Polymer/core-input/issues/41
The Dart element uses information from JS comments to generate type annotations and the comment in the JavaScript element contains the wrong type information.
As a workaround you can call the JS function directly:
void setCustomValidity(CoreInput inp, String message) {
inp.jsElement.callMethod('setCustomValidity', ["Give me more!"]);
}
see also Taking total control of PaperInput validation
I understand there are a few similar questions (e.g. here), but they all seem to be in different context. This is what I see in my chrome console:
Unhandled rejection reasons (should be empty):
["TypeError: Cannot read property 'compound' of null…://localhost:1476/Scripts/breeze.debug.js:234:15)", joinBy: function, equals: function, indexByKey: function, getByKey: function, sortOn: function]
I could see this error in my debugger at failed(error):
return manager.executeQuery(query).then(succeeded).fail(failed);
function failed(error) {
logger.logError(error);
}
For a specific object, it happens most of time, but no always (maybe one out of 10 is okay). The query from server returns without exception. As I figured, it seems to be related to the query with a specific include of table. However, in fact, in this case, the included table doesn't have any related entry yet (if there is an entry, it doesn't seem to have any problem). Any idea?
Okay, I accidentally found out what has caused this error. It is metadatastore post-construction initializer like
manager.metadataStore.registerEntityTypeCtor("Result", Result, initialize);
// constructor
function Result() {
}
// post-construction initializer
function initialize(result) {
result.cmpName = result.cs.compound.name;
}
where result.cs could be null sometimes.
Too bad the error message didn't provide any clue.