Nativescript:滚动时，Listview项正在重用 [英] Nativescript: Listview items are reusing when scrolling

问题描述

我试图通过单击存储[<Label>] 将产品添加到购物车.然后，我正在更改该添加列表的标签颜色.

I am trying to add products to Cart by clicking STORE [<Label>]. Then, I am changing label's color for that added list.

在那之后，我试图通过滚动添加更多产品.自动地，其他ListView列表的标签颜色更改了.

After that, I am trying to add more products, by scrolling. Automatically, some other ListView list's label color changed.

我知道这些行为将在iOS的UITableView中发生.借助NSDictionary，我可以解决这个问题. 在iOS中重新使用Tableview

I know these behaviour will happen in UITableView in iOS. With the help of NSDictionary, I can handle this. Tableview Reusing in iOS

我不知道如何在NativeScript

编码

.js

exports.cartColorChange = function(args) {
    var lbl = args.object;
    lbl.color = "rgb(171, 0, 230)";
};

.xml

<ListView col="0" row="2" items="{{ mySecondItems }}" id="myListVw" itemLoading="listViewItemsLoading" itemTap="secondListViewItemTap" class="list-group" separatorColor="transparent">
<ListView.itemTemplate>

<GridLayout class="listGrid" columns="75,*" rows="*" width="100%" height="90" >
  <Label col="0" row="0" class="roundCircle" text="{{ price }}" textWrap="true"  />

  <StackLayout col="1" row="0" orientation="vertical" verticalAlignment="center">
       <Label class="booksubtitle" text="{{ subtitle }}" textWrap="true" id="wow"  />
       <Label class="bookTitle" text="{{ title }}" textWrap="true"  />
       <Label class="addCart" text="&#xf291;" textWrap="true" tap="cartColorChange" />

  </StackLayout>
</GridLayout>
</ListView.itemTemplate>
</ListView>

.css

Label.addCart{

    text-align: right;
    color: rgb(220, 220, 220);
    margin-right: 15px;
    margin-bottom: 0px;
    font-size: 15px;
    font-family: "FontAwesome";
}

输出:

推荐答案

您正在直接更改渲染对象的颜色，因为当回收对象时，该颜色会保持该颜色.

you are directly changing color of the rendered object because of which when object is recycled it persist that color.

您可以通过单击对象时更改对象属性来达到相同的效果.并基于该属性应用样式.像className="{{isClicked?'clickedCart':'notClickedCart'}}"或stle.color="{{isClicked?'red':'blue'}}"

you can achieve same effect by changing object property when clicked. and based on that property applying styles. like className="{{isClicked?'clickedCart':'notClickedCart'}}" or stle.color="{{isClicked?'red':'blue'}}"

这是更新的游乐场演示: https://play.nativescript.org/?template=play-js&id=T6sna8&v=8

here is updated playground demo:https://play.nativescript.org/?template=play-js&id=T6sna8&v=8

编码

.js

exports.cartColorChange = function(args) {
    var lbl = args.object;
    var item=lbl.bindingContext;
    var index = secondArray.indexOf(item)
    console.log("Clicked item with index " + index);
    item.isClicked = !item.isClicked;
    secondArray.setItem(index,item);
    // lbl.color = "rgb(171, 0, 230)";
};

.xml

<ListView col="0" row="2" items="{{ mySecondItems }}" id="myListVw" itemLoading="listViewItemsLoading" itemTap="secondListViewItemTap" class="list-group" separatorColor="transparent">
<ListView.itemTemplate>

<GridLayout class="listGrid" columns="75,*" rows="*" width="100%" height="90" >
  <Label col="0" row="0" class="roundCircle" text="{{ price }}" textWrap="true"  />

  <StackLayout col="1" row="0" orientation="vertical" verticalAlignment="center">
       <Label class="booksubtitle" text="{{ subtitle }}" textWrap="true" id="wow"  />
       <Label class="bookTitle" text="{{ title }}" textWrap="true"  />
       <Label class="addCart" className="{{isClicked?'clickedCart':'notClickedCart'}}" text="&#xf291;" textWrap="true" tap="cartColorChange" />

  </StackLayout>
</GridLayout>
</ListView.itemTemplate>
</ListView>

.css

Label.clickedCart{
    color:rgb(171, 0, 230);
}

Label.notClickedCart{
    color:gray;
}

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