Carousel becomes blank when removing last item from data list

[bozha-step]

Describe the bug Removing last item from carousel data list will result in blank carousel. Similar issue to https://github.com/meliorence/react-native-snap-carousel/issues/623 & https://github.com/dohooo/react-native-reanimated-carousel/issues/550.

To Reproduce Create carousel with data list e.g [A, B, C], remove last item C from data list, the carousel will be blank.

Expected behavior The carousel should render item B when item C is removed from data list.

Screenshots If applicable, add screenshots to help explain your problem.

Versions (please complete the following information):

• react-native: v0.73.2
• react-native-reanimated: v3.6.1
• react-native-reanimated-carousel: v3.5.1
• react-native-gesture-handler: v2.14.0

Smartphone (please complete the following information):

• Device: [iPhone 11 Pro Max Simulator]

Additional context Add any other context about the problem here.

[dosubot[bot]]

Thank you for providing the detailed context. I understand that you're experiencing an issue where the carousel becomes blank when the last item is removed from the data list. This issue seems to be similar to a few open issues in the react-native-reanimated-carousel repository, specifically issue #550 and issue #464.

Based on the information from these issues, there are a couple of potential solutions you could try:

1. Use a stable key for each item in the carousel: The carousel might be re-rendering because the key for each item is changing when an item is removed. This is because the key for each item is its index in the data array. When an item is removed from the data array, the indices of all subsequent items change, causing them to re-render. To prevent this, you can use a property of each item that is unique and stable as the key. Here's how you can modify the code:

return (
  <>
    {
      data.map((item, index) => {
        const realIndex = computedRealIndexWithAutoFillData({
          index,
          dataLength: rawDataLength,
          loop,
          autoFillData,
        });

        const { negativeRange, positiveRange } = displayedItems;
        const shouldRender = (index >= negativeRange[0] && index <= negativeRange[1])
          || (index >= positiveRange[0] && index <= positiveRange[1]);

        if (!shouldRender)
          return null;

        return (
          <BaseLayout
            key={item.userId} // Use item.userId as the key
            index={index}
            handlerOffset={offsetX}
            visibleRanges={visibleRanges}
            animationStyle={customAnimation || layoutConfig}
          >
            {({ animationValue }) =>
              renderItem({
                item,
                index: realIndex,
                animationValue,
              })
            }
          </BaseLayout>
        );
      })
    }
  </>
);

This assumes that each item in the data array has a unique userId property. If that's not the case, you'll need to find another property to use, or generate a unique id for each item when it's added to the array. You can find more information about this in the ItemRenderer.tsx file in the repository.

2. Force a re-render of the Carousel component when the data length changes: Another workaround involves using the length of the data array as the key for the Carousel component, which forces the component to re-render when the data length changes. Here's how you can do it:

<Carousel key={data.length} data={data} />

This workaround was found in a comment on issue #272 and has received positive feedback.

Please try these solutions and let me know if they help resolve your issue. If not, we can continue to investigate further.

Sources

• Removing last item requires manual swipe to view previous item
• Re-render on element removal
• Dynamically updating data count
• Malfunctions occur when changing data.
• src/components/Carousel.tsx

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[fikkatra]

Possible duplicate of https://github.com/dohooo/react-native-reanimated-carousel/issues/550

[Vladislava9009]

suggested solution doesn't work

[sinanverve7]

I didn't understand first approach, second approach is working , but someone claiming it isn't perfomant