swiper item can't be hot add?

[ytxDaXiong]

I download img from server then add the new item into the swiper items List.
next setState() but it give me an error like this.
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (21956): The following assertion was thrown building NotificationListener:
I/flutter (21956): ScrollController not attached to any scroll views.
I/flutter (21956): 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 110 pos 12:
I/flutter (21956): '_positions.isNotEmpty'
I/flutter (21956):
I/flutter (21956): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (21956): more information in this error message to help you determine and fix the underlying cause.
I/flutter (21956): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (21956): https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter (21956):
I/flutter (21956): When the exception was thrown, this was the stack:
I/flutter (21956): #2 ScrollController.position (package:flutter/src/widgets/scroll_controller.dart:110:12)
I/flutter (21956): #3 PageController.animateToPage (package:flutter/src/widgets/page_view.dart:119:41)
I/flutter (21956): #4 _TransformerPageViewState.didUpdateWidget (package:transformer_page_view/transformer_page_view.dart:511:25)
I/flutter (21956): #5 StatefulElement.update (package:flutter/src/widgets/framework.dart:3879:58)
I/flutter (21956): #6 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #7 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3747:16)
I/flutter (21956): #8 Element.rebuild (package:flutter/src/widgets/framework.dart:3559:5)
I/flutter (21956): #9 StatelessElement.update (package:flutter/src/widgets/framework.dart:3796:5)
I/flutter (21956): #10 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #11 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4601:32)
I/flutter (21956): #12 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4992:17)
I/flutter (21956): #13 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #14 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3747:16)
I/flutter (21956): #15 Element.rebuild (package:flutter/src/widgets/framework.dart:3559:5)
I/flutter (21956): #16 StatefulElement.update (package:flutter/src/widgets/framework.dart:3894:5)
I/flutter (21956): #17 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #18 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4601:32)
I/flutter (21956): #19 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4992:17)
I/flutter (21956): #20 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #21 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4883:14)
I/flutter (21956): #22 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #23 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3747:16)
I/flutter (21956): #24 Element.rebuild (package:flutter/src/widgets/framework.dart:3559:5)
I/flutter (21956): #25 StatelessElement.update (package:flutter/src/widgets/framework.dart:3796:5)
I/flutter (21956): #26 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #27 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3747:16)
I/flutter (21956): #28 Element.rebuild (package:flutter/src/widgets/framework.dart:3559:5)
I/flutter (21956): #29 ProxyElement.update (package:flutter/src/widgets/framework.dart:4006:5)
I/flutter (21956): #30 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)
I/flutter (21956): #31 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3747:16)
I/flutter (21956): #32 Element.rebuild (package:flutter/src/widgets/framework.dart:3559:5)
I/flutter (21956): #33 ProxyElement.update (package:flutter/src/widgets/framework.dart:4006:5)
I/flutter (21956): #34 Element.updateChild (package:flutter/src/widgets/framework.dart:2748:15)

[ytxDaXiong]

I found the swiper.js has observer can update item, if the package can do it?

[ytxDaXiong]

I found that if the new itemCount is the same as the init count. it's will play normal

[zhouxting]

Before setState，use method stopAutoplay and method move(0) of swiperController

[ytxDaXiong]

Before setState，use method stopAutoplay and method move(0) of swiperController

I have try, but it doesn't work and return the same error

[zhouxting]

The following is what I write and it works

Widget build(BuildContext context) {
_controller.stopAutoplay();
_controller.move(0);
var widget= new Container(
width: MediaQuery.of(context).size.width,
height: 200.0,
child:Builder(builder: (context){
return new ScopedModelDescendant(
builder: (context,widget,model){
return model.imageFiles.length>0? new Swiper(
autoplay: true,
itemBuilder: (BuildContext context, int index) {
if(model.imageFiles[index]!=null){
return model.imageFiles[index];
}else{
return new Image.asset("assets/images/loading.jpg");
}
},
itemCount:model.imageFiles.length,
itemHeight: 200,
itemWidth: MediaQuery.of(context).size.width,
pagination: new SwiperPagination(),
controller: _controller,
):new Image.asset("assets/images/loading.jpg");
},
);
})
)；
_controller.startAutoplay();
return widget;
}

[ytxDaXiong]

The following is what I write and it works

Widget build(BuildContext context) {
_controller.stopAutoplay();
_controller.move(0);
var widget= new Container(
width: MediaQuery.of(context).size.width,
height: 200.0,
child:Builder(builder: (context){
return new ScopedModelDescendant(
builder: (context,widget,model){
return model.imageFiles.length>0? new Swiper(
autoplay: true,
itemBuilder: (BuildContext context, int index) {
if(model.imageFiles[index]!=null){
return model.imageFiles[index];
}else{
return new Image.asset("assets/images/loading.jpg");
}
},
itemCount:model.imageFiles.length,
itemHeight: 200,
itemWidth: MediaQuery.of(context).size.width,
pagination: new SwiperPagination(),
controller: _controller,
):new Image.asset("assets/images/loading.jpg");
},
);
})
)；
_controller.startAutoplay();
return widget;
}

thanks a lot but it still does't work for me。if the itemCount changed the program will return the same error

[ytxDaXiong]

@zhouxting your solutions create swiper after list has value. however, i need to create swiper first when img download finished next to setState();

[ytxDaXiong]

oh! ,i solve the problem by set different key . i will close the issue

[Tokenyet]

I suggested this should be added in Readme, It's easy to happen on hot loading and failed randomly.

[JunwuHuang]

oh! ,i solve the problem by set different key . i will close the issue

which widget i should set key

[451518849]

我的解决方案是给Swiper设置一个key，当需要更新item的个数时，根据item的不同长度给Swiper使用不同的key就行，我使用的key是: ValueKey(items.length)

[quanzaiyu]

I had the same problem and I solved it by same way. Thanks a lot !

[lifelikejuly]

oh! ,i solve the problem by set different key . i will close the issue

Please what's mean about set diff key to solve this problem. I had the same problem

[DennisMuchiri]

oh! ,i solve the problem by set different key . i will close the issue

please share the code

[waqas-alii]

My solution is to set a key for Swiper. When the number of items needs to be updated, use different keys for Swiper according to the different lengths of the items. The key I use is: ValueKey (items.length)

[poonkuzhalik]

My solution is to set a key for Swiper. When the number of items needs to be updated, use different keys for Swiper according to the different lengths of the items. The key I use is: ValueKey (items.length)

Works!!! Awesome