How to display individual cache data from React-Query?

Question

My application has a user input a query, then fetches the response data and is also cached.

For each cache data, I want to display a button for every previous query that users can click to again load that data on the screen.

Let's say I first input the id 1, then the data is cached and rendered. When I log my cached data with Object.values(cacheData.queriesMap) I receive {["rickandmorty",0]: Query, ["rickandmorty","1"]: Query}. I now want to iterate through my cached data and display each individual query.

// <Home />
const cachedCharacters = Object.values(cacheData.queriesMap).map(character => (
    <button>{character.state.data.name}</button>
))

return (
    <div>
      {cachedCharacters}
    </div>
)

However, I receive a TypeError: Cannot read property 'name' of undefined. I suspect the reason for this error is because the first query is ["rickandmorty",0], a non-existing item that the application had fetched upon mounting.

I then set up my application to disable fetching upon component mount.

// <Home/>
const { isLoading, error, data } = useQuery(
    ["rickandmorty", idQuery],
    handleRickAndMortyFetch,
    {
      enabled: false || idQuery !== 0,
  );

Yet, the application still makes the initial fetch upon mounting. If I first input the id 1, I again receive {["rickandmorty",0]: Query, ["rickandmorty","1"]: Query}.

If the initial fetch is what's preventing each individual cache data to be rendered, how do I disable the initial fetch if enabled: false is not working? If it's a different issue preventing each individual cache data to be rendered, kindly suggest a solution. https://codesandbox.io/s/rick-and-morty-render-cache-data-8dv6y

Leomar Amiel · Accepted Answer · 2021-04-06 06:32:40Z

2

Your code is correct. The initial query in the dev-tools you are seeing doesn't necessarily mean it is getting fetched. If you look through the state of the idQuery 0, there are no counts of it having its' data/error being updated. It's just in an idle state.

I suggest you try and filter your cacheData.queriesMap initially before mapping to make sure that your characters have data. You can either check the state.data or make sure the query has a state.status === 'success'. Or the easiest way might be to just show which queries already have data.

  const cachedCharacters = Object.values(
    cacheData.queriesMap
  ).map((character, index) => (
    <>
      {character.state.data ? (
        <button key={`${character.state.data.name}${index}`}>
          {character.state.data.name}
        </button>
      ) : null}
    </>
  ));

answered Apr 6, 2021 at 6:32

Leomar Amiel

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1 Comment

ln09nv2 Over a year ago

I now see that idQuery 0 is an idle state. Thank you for the clear solution! @Leomar-amiel

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