@apollo/react-hooks
This tutorial outlines some of the @apollo/react-hooks API reference
Installation
npm install @apollo/react-hooks
useQuery
The code snippet below demonstrates how to use the useQuery package of the @apollo/react-hooks
import {useQuery} from '@apollo/react-hooks';
import gql from 'graphql-tag';
const GET_GREETING = gql`
query getGreeting($language: String!) {
greeting(language: $language) {
message
}
}
`;
function Hello() {
const { loading, error, data } = useQuery(GET_GREETING, {
variables: { language: 'english' },
});
if (loading) return <p>Loading ...</p>;
return <h1>Hello {data.greeting.message}!</h1>;
}
Function Signature
function useQuery<TData = any, TVariables = OperationVariables>(
query: DocumentNode,
options?: QueryHookOptions<TData, TVariables>,
): QueryResult<TData, TVariables> {}
Params
query
PARAM | TYPE | DESCRIPTION |
---|---|---|
query | DocumentNode | A GraphQL query document parsed into an AST by graphql-tag. |
options
OPTION | TYPE | DESCRIPTION |
---|---|---|
query | DocumentNode | A GraphQL query document parsed into an AST by graphql-tag. Optional for the useQuery Hook since the query can be passed in as the first parameter to the Hook. Required for the Query component. |
variables | { [key: string]: any } | An object containing all of the variables your query needs to execute |
pollInterval | number | Specifies the interval in ms at which you want your component to poll for data. Defaults to 0 (no polling). |
notifyOnNetworkStatusChange | boolean | Whether updates to the network status or network error should re-render your component. Defaults to false. |
fetchPolicy | FetchPolicy | How you want your component to interact with the Apollo cache. Defaults to "cache-first". |
errorPolicy | ErrorPolicy | How you want your component to handle network and GraphQL errors. Defaults to "none", which means we treat GraphQL errors as runtime errors. |
ssr | boolean | Pass in false to skip your query during server-side rendering. |
displayName | string | The name of your component to be displayed in React DevTools. Defaults to 'Query'. |
skip | boolean | If skip is true, the query will be skipped entirely. Not available with useLazyQuery. |
onCompleted | (data: TData | {}) => void | A callback executed once your query successfully completes. |
onError | (error: ApolloError) => void | A callback executed in the event of an error. |
context | Record<string, any> | Shared context between your component and your network interface (Apollo Link). |
partialRefetch | boolean | If true, perform a query refetch if the query result is marked as being partial, and the returned data is reset to an empty Object by the Apollo Client QueryManager (due to a cache miss). The default value is false for backwards-compatibility's sake, but should be changed to true for most use-cases. |
client | ApolloClient | An ApolloClient instance. By default useQuery / Query uses the client passed down via context, but a different client can be passed in. |
returnPartialData | boolean | Opt into receiving partial results from the cache for queries that are not fully satisfied by the cache. false by default. |
Result
PROPERTY | TYPE | DESCRIPTION |
---|---|---|
data | TData | An object containing the result of your GraphQL query. Defaults to undefined. |
loading | boolean | A boolean that indicates whether the request is in flight |
error | ApolloError | A runtime error with graphQLErrors and networkError properties |
variables | { [key: string]: any } | An object containing the variables the query was called with |
networkStatus | NetworkStatus | A number from 1-8 corresponding to the detailed state of your network request. Includes information about refetching and polling status. Used in conjunction with the notifyOnNetworkStatusChange prop. |
refetch | (variables?: TVariables) => Promise |
A function that allows you to refetch the query and optionally pass in new variables |
fetchMore | ({ query?: DocumentNode, variables?: TVariables, updateQuery: Function}) => Promise<ApolloQueryResult> | A function that enables pagination for your query |
startPolling | (interval: number) => void | This function sets up an interval in ms and fetches the query each time the specified interval passes. |
stopPolling | () => void | This function stops the query from polling. |
subscribeToMore | (options: { document: DocumentNode, variables?: TVariables, updateQuery?: Function, onError?: Function}) => () => void | A function that sets up a subscription. subscribeToMore returns a function that you can use to unsubscribe. |
updateQuery | (previousResult: TData, options: { variables: TVariables }) => TData | A function that allows you to update the query's result in the cache outside the context of a fetch, mutation, or subscription |
client | ApolloClient | Your ApolloClient instance. Useful for manually firing queries or writing data to the cache. |
called | boolean | A boolean indicating if the query function has been called, used by useLazyQuery (not set for useQuery / Query). |
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