useQuery

Example

React Concurrent Mode is enabled by default for Blitz apps. So the

<Suspense> component is used for loading states and <ErrorBoundary> is used to display errors. If you need, you can read the React Concurrent Mode Docs.

import {Suspense} from "react"
import {useQuery, useRouter} from "blitz"
import getProject from "app/projects/queries/getProject"
import ErrorBoundary from "app/components/ErrorBoundary"
function Project() {
  const router = useRouter()
  const projectId = parseInt(router.query.projectId as string)
  const [project] = useQuery(getProject, {where: {id: projectId}})
  return <div>{project.name}</div>
}
function WrappedProject() {
  return (
    <div>
      <ErrorBoundary fallback={(error) => <div>Error: {JSON.stringify(error)}</div>}>
        <Suspense fallback={<div>Loading...</div>}>
          <Project />
        </Suspense>
      </ErrorBoundary>
    </div>
  )
}
export default WrappedProject

For more examples and use cases, see the

query usage documentation.

API

const [
  queryFunctionResults,
  {
    isFetching,
    failureCount,
    refetch,
    mutate,
  }
] = useQuery(blitzQueryFunction, queryInputArguments, {
  manual,
  enabled,
  retry,
  retryDelay,
  staleTime,
  cacheTime,
  refetchInterval,
  refetchIntervalInBackground,
  refetchOnWindowFocus,
  onSuccess,
  onError,
  onSettled,
  suspense,
  initialData,
  refetchOnMount,
})

Arguments

• blitzQueryFunction: A Blitz query function
  • Required
• queryInputArguments
  • Required
  • The arguments that will be passed to blitzQueryFunction
• options
  • Optional

Options

• manual: Boolean
  • Set this to true to disable automatic refetching when the query mounts or input arguments change.
  • To refetch the query, use the refetch method returned from the useQuery instance.
• enabled: Boolean
  • Set this to false to disable automatic refetching when the query mounts or changes query keys.
  • To refetch the query, use the refetch method returned from the useQuery instance.
• retry: Boolean | Int | Function(failureCount, error) => shouldRetry | Boolean
  • If false, failed queries will not retry by default.
  • If true, failed queries will retry infinitely.
  • If set to an Int, e.g. 3, failed queries will retry until the failed query count meets that number.
  • If set to a function (failureCount, error) => boolean failed queries will retry until the function returns false.
• retryDelay: Function(retryAttempt: Int) => Int
  • This function receives a retryAttempt integer and returns the delay to apply before the next attempt in milliseconds.
  • A function like attempt => Math.min(attempt > 1 ? 2 ** attempt * 1000 : 1000, 30 * 1000) applies exponential backoff.
  • A function like attempt => attempt * 1000 applies linear backoff.
• staleTime: Int | Infinity
  • The time in milliseconds that cache data remains fresh. After a successful cache update, that cache data will become stale after this duration.
  • If set to Infinity, query will never go stale
• cacheTime: Int | Infinity
  • The time in milliseconds that unused/inactive cache data remains in memory. When a query's cache becomes unused or inactive, that cache data will be garbage collected after this duration.
  • If set to Infinity, will disable garbage collection
• refetchInterval: false | Integer
  • Optional
  • If set to a number, all queries will continuously refetch at this frequency in milliseconds
• refetchIntervalInBackground: Boolean
  • Optional
  • If set to true, queries that are set to continuously refetch with a refetchInterval will continue to refetch while their tab/window is in the background
• refetchOnWindowFocus: Boolean
  • Optional
  • Set this to false to disable automatic refetching on window focus (useful, when refetchAllOnWindowFocus is set to true).
  • Set this to true to enable automatic refetching on window focus (useful, when refetchAllOnWindowFocus is set to false.
• onSuccess: Function(data) => data
  • Optional
  • This function will fire any time the query successfully fetches new data.
• onError: Function(err) => void
  • Optional
  • This function will fire if the query encounters an error and will be passed the error.
• onSettled: Function(data, error) => data
  • Optional
  • This function will fire any time the query is either successfully fetched or errors and be passed either the data or error
• initialData: any | Function() => any
  • Optional
  • If set, this value will be used as the initial data for the query cache (as long as the query hasn't been created or cached yet)
  • If set to a function, the function will be called once during the shared/root query initialization, and be expected to synchronously return the initialData
• refetchOnMount: Boolean
  • Optional
  • Defaults to true
  • If set to false, will disable additional instances of a query to trigger background refetches
• suspense: Boolean
  • Optional
  • Enabled by default. Set this to false to disable suspense mode.

Returns

[queryFunctionResults, queryExtras]

queryFunctionResults: Any

• Defaults to undefined.
• The last successfully resolved data for the query.

queryExtras: Object

• isFetching: Boolean
  • Defaults to true so long as manual is set to false
  • Will be true if the query is currently fetching, including background fetching.
• failureCount: Integer
  • The failure count for the query.
  • Incremented every time the query fails.
  • Reset to 0 when the query succeeds.
• refetch() - Function({ force, throwOnError }) => void
  • A function to manually refetch the query if it is stale.
  • To bypass the stale check, you can pass the force: true option and refetch it regardless of it's freshness
  • If the query errors, the error will only be logged. If you want an error to be thrown, pass the throwOnError: true option
• mutate() - Function(newData, opts) => void
  • A function to manually update the cache for a query.
  • newData can be an object of new data or a function that receives the old data and returns the new data
  • This is often used to instantly update the cache after submitting a form
  • After updating the cache, this will automatically call refetch() to ensure the data is correct. Disable refetch by passing an options object {refetch: false} as the second argument.
  • See the Blitz mutation usage docs for example usage of mutate()