useQuery: Attempted to assign to readonly property

user_17653656 0
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I get data from useQuery. And I want to sort them by data field directFeedNumber.

  const { data: allFeedData, loading: allFeedLoading } =
    useQuery(SEE_ALL_FEED_ORDER);

  const FeedSort = allFeedData.seeAllFeedOrder.sort(function (a, b) {
    return a - b;
  });

So I use sort function to do this, but when I console.log FeedSort, it says Attempted to assign to readonly property.

So can't I use sort function with data got from useQuery?

Then how can I sort them? Please help me!!

react-native gql hook javascript
1 Answers

Array.sort alters the original array, unlike other methods such as Array.map which produce a new array.

In order to prevent this, we can make a shallow copy of the original array.

Example:

const { data: allFeedData, loading: allFeedLoading } = useQuery(SEE_ALL_FEED_ORDER);

const FeedSort = [...allFeedData.seeAllFeedOrder].sort(function (a, b) {
   return a - b;
});

What we do here is create a new array and populate it with the values of the original array using the spread syntax.

Then we sort the newly created array, which we can alter.

Note: there are also other ways of making shallow copies, or deep copies for that matter, of arrays and objects.
Here are some other examples.

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