Refetching Queries with Different Data

When referring to "refetching a query", we mean fetching the query again for different data than was originally rendered by the query. For example, this might be to change a currently selected item, to render a different list of items than the one being shown, or more generally to transition the currently rendered content to show new or different content.

When using useQueryLoader / loadQuery

Similarly to Refreshing Queries with useQueryLoader, we can also use the useQueryLoader Hook described in our Fetching Queries for Render section, but this time passing different query variables:

/**
 * App.react.js
 */
const AppQuery = require('__generated__/AppQuery.graphql');

function App(props: Props) {
  const variables = {id: '4'};
  const [queryRef, loadQuery] = useQueryLoader(
    AppQuery,
    props.appQueryRef /* initial query ref */
  );

  const refetch = useCallback(() => {
    // Load the query again using the same original variables.
    // Calling loadQuery will update the value of queryRef.
    loadQuery({id: 'different-id'});
  }, [/* ... */]);

  return (
    <React.Suspense fallback="Loading query...">
      <MainContent
        refetch={refetch}
        queryRef={queryRef}
      />
    </React.Suspense>
  );
}

/**
 * MainContent.react.js
 */

// Renders the preloaded query, given the query reference
function MainContent(props) {
  const {refetch, queryRef} = props;
  const data = usePreloadedQuery(
    graphql`
      query AppQuery($id: ID!) {
        user(id: $id) {
          name
          friends {
            count
          }
        }
      }
    `,
    queryRef,
  );

  return (
    <>
      <h1>{data.user?.name}</h1>
      <div>Friends count: {data.user?.friends?.count}</div>
      <Button
        onClick={() => refetch()}>
        Fetch latest count
      </Button>
    </>
  );
}

Let's distill what's going on here:

• We call loadQuery in the event handler for refetching, so the network request starts immediately, and then pass the queryRef to usePreloadedQuery, so it renders the updated data.
• We are not passing a fetchPolicy to loadQuery, meaning that it will use the default value of 'store-or-network'. We could provide a different policy in order to specify whether to use locally cached data (as we covered in Reusing Cached Data For Render).
• Calling loadQuery will re-render the component and may cause usePreloadedQuery to suspend (as explained in Loading States with Suspense). This means that we'll need to make sure that there's a Suspense boundary wrapping the MainContent component, in order to show a fallback loading state.

If you need to avoid Suspense

In some cases, you might want to avoid showing a Suspense fallback, which would hide the already rendered content. For these cases, you can use fetchQuery instead, and manually keep track of a loading state:

/**
 * App.react.js
 */
const AppQuery = require('__generated__/AppQuery.graphql');

function App(props: Props) {
  const environment = useRelayEnvironment();
  const [queryRef, loadQuery] = useQueryLoader(
    AppQuery,
    props.appQueryRef /* initial query ref */
  );
  const [isRefetching, setIsRefetching] = useState(false)

  const refetch = useCallback(() => {
    if (isRefetching) { return; }
    setIsRefetching(true);
    const variables = { id: 'different-id' };

    // fetchQuery will fetch the query and write
    // the data to the Relay store. This will ensure
    // that when we re-render, the data is already
    // cached and we don't suspend
    fetchQuery(environment, AppQuery, variables)
      .subscribe({
        complete: () => {
          setIsRefetching(false);

          // *After* the query has been fetched, we call
          // loadQuery again to re-render with a new
          // queryRef.
          // At this point the data for the query should
          // be cached, so we use the 'store-only'
          // fetchPolicy to avoid suspending.
          loadQuery(variables, {fetchPolicy: 'store-only'});
        },
        error: () => {
          setIsRefetching(false);
        }
      });
  }, [/* ... */]);

  return (
    <React.Suspense fallback="Loading query...">
      <MainContent
        isRefetching={isRefetching}
        refetch={refetch}
        queryRef={queryRef}
      />
    </React.Suspense>
  );
}

Let's distill what's going on here:

• When refetching, we now keep track of our own isRefetching loading state, since we are avoiding suspending. We can use this state to render a busy spinner or similar loading UI inside the MainContent component, without hiding the MainContent.
• In the event handler, we first call fetchQuery, which will fetch the query and write the data to the local Relay store. When the fetchQuery network request completes, we call loadQuery so that we obtain an updated queryRef that we then pass to usePreloadedQuery in order render the updated data, similar to the previous example.
• At this point, when loadQuery is called, the data for the query should already be cached in the local Relay store, so we use fetchPolicy of 'store-only' to avoid suspending and only read the already cached data.

When using useLazyLoadQuery

Similarly to Refreshing Queries with useLazyLoadQuery, we can also use the useLazyLoadQuery Hook described in our Lazily Fetching Queries during Render section, but this time passing different query variables:

/**
 * App.react.js
 */
const AppQuery = require('__generated__/AppQuery.graphql');

function App(props: Props) {
  const [queryArgs, setQueryArgs] = useState({
    options: {fetchKey: 0},
    variables: {id: '4'},
  });

  const refetch = useCallback(() => {
    // Trigger a re-render of useLazyLoadQuery with new variables,
    // *and* an updated fetchKey.
    // The new fetchKey will ensure that the query is fully
    // re-evaluated and refetched.
    setQueryArgs(prev => ({
      options: {
        fetchKey: (prev?.options.fetchKey ?? 0) + 1,
      },
      variables: {id: 'different-id'}
    }));
  }, [/* ... */]);

  return (
    <React.Suspense fallback="Loading query...">
      <MainContent
        refetch={refetch}
        queryArgs={queryArgs}
      />
    </React.Suspense>
  );
}

/**
 * MainContent.react.js
 */
// Fetches and renders the query, given the fetch options
function MainContent(props) {
  const {refetch, queryArgs} = props;
  const data = useLazyLoadQuery(
    graphql`
      query AppQuery($id: ID!) {
        user(id: $id) {
          name
          friends {
            count
          }
        }
      }
    `,
    queryArgs.variables,
    queryArgs.options,
  );

  return (
    <>
      <h1>{data.user?.name}</h1>
      <div>Friends count: {data.user.friends?.count}</div>
      <Button
        onClick={() => refetch()}>
        Fetch latest count
      </Button>
    </>
  );
}

Let's distill what's going on here:

• We update the component in the event handler for refreshing by setting new query args in state. This will cause the MainContent component that uses useLazyLoadQuery to re-render with the new variables and fetchKey, and refetch the query upon rendering.
• We are passing a new value of fetchKey which we increment on every update. Passing a new fetchKey to useLazyLoadQuery on every update will ensure that the query is fully re-evaluated and refetched.
• We are not passing a new fetchPolicy to useLazyLoadQuery, meaning that it will use the default value of 'store-or-network'. We could provide a different policy in order to specify whether to use locally cached data (as we covered in Reusing Cached Data For Render).
• The state update in refetch will re-render the component and may cause the component to suspend (as explained in Loading States with Suspense). This means that we'll need to make sure that there's a Suspense boundary wrapping the MainContent component, in order to show a fallback loading state.

If you need to avoid Suspense

In some cases, you might want to avoid showing a Suspense fallback, which would hide the already rendered content. For these cases, you can use fetchQuery instead, and manually keep track of a loading state:

/**
 * App.react.js
 */
const AppQuery = require('__generated__/AppQuery.graphql');

function App(props: Props) {
  const environment = useRelayEnvironment();
  const [isRefreshing, setIsRefreshing] = useState(false)
  const [queryArgs, setQueryArgs] = useState({
    options: {fetchKey: 0, fetchPolicy: 'store-or-network'},
    variables: {id: '4'},
  });

  const refetch = useCallback(() => {
    if (isRefreshing) { return; }
    setIsRefreshing(true);
    const variables = { id: 'different-id' };

    // fetchQuery will fetch the query and write
    // the data to the Relay store. This will ensure
    // that when we re-render, the data is already
    // cached and we don't suspend
    fetchQuery(environment, AppQuery, variables)
      .subscribe({
        complete: () => {
          setIsRefreshing(false);

          // *After* the query has been fetched, we update
          // our state to re-render with the new fetchKey
          // and fetchPolicy.
          // At this point the data for the query should
          // be cached, so we use the 'store-only'
          // fetchPolicy to avoid suspending.
          setQueryArgs(prev => ({
            options: {
              fetchKey: (prev?.options.fetchKey ?? 0) + 1,
              fetchPolicy: 'store-only',
            },
            variables,
          }));
        },
        error: () => {
          setIsRefreshing(false);
        }
      });
  }, [/* ... */]);

  return (
    <React.Suspense fallback="Loading query...">
      <MainContent
        isRefetching={isRefetching}
        refetch={refetch}
        queryArgs={queryArgs}
      />
    </React.Suspense>
  );
}

Let's distill what's going on here:

• When refetching, we now keep track of our own isRefetching loading state, since we are avoiding suspending. We can use this state to render a busy spinner or similar loading UI inside the MainContent component, without hiding the MainContent.
• In the event handler, we first call fetchQuery, which will fetch the query and write the data to the local Relay store. When the fetchQuery network request completes, we update our state so that we re-render an updated fetchKey and fetchPolicy that we then pass to useLazyLoadQuery in order render the updated data, similar to the previous example.
• At this point, when we update the state, the data for the query should already be cached in the local Relay store, so we use fetchPolicy of 'store-only' to avoid suspending and only read the already cached data.

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