# Smart Query

Each query declared in the apollo definition (that is, which doesn't start with a $ char) in a component results in the creation of a smart query object.

# Options

  • query: GraphQL document (can be a file or a gql string).
  • variables: Object or reactive function that returns an object. Each key will be mapped with a '$' in the GraphQL document, for example foo will become $foo.
  • throttle: throttle variables updates (in ms).
  • debounce: debounce variables updates (in ms).
  • pollInterval: auto update using polling (which means refetching every x ms). Default: undefined, 0 - stop polling.
  • update(data) {return ...} to customize the value that is set in the vue property, for example if the field names don't match.
  • result(ApolloQueryResult, key) is a hook called when a result is received (see documentation for ApolloQueryResult). key is the query key in the apollo option.
  • error(error, vm, key, type, options) is a hook called when there are errors. error is an Apollo error object with either a graphQLErrors property or a networkError property. vm is the related component instance. key is the smart query key. type is either 'query' or 'subscription'. options is the final watchQuery options object.
  • loadingKey will update the component data property you pass as the value. You should initialize this property to 0 in the component data() hook. When the query is loading, this property will be incremented by 1; when it is no longer loading, it will be decremented by 1. That way, the property can represent a counter of currently loading queries.
  • watchLoading(isLoading, countModifier) is a hook called when the loading state of the query changes. The countModifier parameter is either equal to 1 when the query is loading, or -1 when the query is no longer loading.
  • manual is a boolean to disable the automatic property update. If you use it, you then need to specify a result callback (see example below).
  • deep is a boolean to use deep: true on Vue watchers.
  • skip is a boolean or a (reactive) function that returns a boolean. The function gets the current component and smart query key as arguments, so it can be used in $query and in ApolloProvider's defaultOptions.
  • subscribeToMore: an object or an array of object which are subscribeToMore options.
  • prefetch is either a boolean or a function to determine if the query should be prefetched. See Server-Side Rendering.
  • You can also use any other watchQuery options (see Apollo docs).

Example:

// Apollo-specific options
apollo: {
  // Advanced query with parameters
  // The 'variables' method is watched by vue
  pingMessage: {
    query: gql`query PingMessage($message: String!) {
      ping(message: $message)
    }`,
    // Reactive parameters
    variables () {
      // Use vue reactive properties here
      return {
        message: this.pingInput,
      }
    },
    // Variables: deep object watch
    deep: false,
    // We use a custom update callback because
    // the field names don't match
    // By default, the 'pingMessage' attribute
    // would be used on the 'data' result object
    // Here we know the result is in the 'ping' attribute
    // considering the way the apollo server works
    update (data) {
      console.log(data)
      // The returned value will update
      // the vue property 'pingMessage'
      return data.ping
    },
    // Optional result hook
    result ({ data, loading, networkStatus }) {
      console.log('We got some result!')
    },
    // Error handling
    error (error) {
      console.error('We\'ve got an error!', error)
    },
    // Loading state
    // loadingKey is the name of the data property
    // that will be incremented when the query is loading
    // and decremented when it no longer is.
    loadingKey: 'loadingQueriesCount',
    // watchLoading will be called whenever the loading state changes
    watchLoading (isLoading, countModifier) {
      // isLoading is a boolean
      // countModifier is either 1 or -1
    },
  },
},

If you use ES2015, you can also write the update like this:

update: data => data.ping

Manual mode example:

{
  query: gql`...`,
  manual: true,
  result ({ data, loading }) {
    if (!loading) {
      this.items = data.items
    }
  },
}

# Properties

# Skip

You can pause or unpause with skip:

this.$apollo.queries.users.skip = true

# loading

Whether the query is loading:

this.$apollo.queries.users.loading

# Methods

# refresh

Stops and restarts the query:

this.$apollo.queries.users.refresh()

# start

Starts the query:

this.$apollo.queries.users.start()

# stop

Stops the query:

this.$apollo.queries.users.stop()

# fetchMore

Load more data for pagination:

this.page++

this.$apollo.queries.tagsPage.fetchMore({
  // New variables
  variables: {
    page: this.page,
    pageSize,
  },
  // Transform the previous result with new data
  updateQuery: (previousResult, { fetchMoreResult }) => {
    const newTags = fetchMoreResult.tagsPage.tags
    const hasMore = fetchMoreResult.tagsPage.hasMore

    this.showMoreEnabled = hasMore

    return {
      tagsPage: {
        __typename: previousResult.tagsPage.__typename,
        // Merging the tag list
        tags: [...previousResult.tagsPage.tags, ...newTags],
        hasMore,
      },
    }
  },
})

# subscribeToMore

Subscribe to more data using GraphQL subscriptions:

// We need to unsubscribe before re-subscribing
if (this.tagsSub) {
  this.tagsSub.unsubscribe()
}
// Subscribe on the query
this.tagsSub = this.$apollo.queries.tags.subscribeToMore({
  document: TAG_ADDED,
  variables: {
    type,
  },
  // Mutate the previous result
  updateQuery: (previousResult, { subscriptionData }) => {
    // If we added the tag already don't do anything
    // This can be caused by the `updateQuery` of our addTag mutation
    if (previousResult.tags.find(tag => tag.id === subscriptionData.data.tagAdded.id)) {
      return previousResult
    }

    return {
      tags: [
        ...previousResult.tags,
        // Add the new tag
        subscriptionData.data.tagAdded,
      ],
    }
  },
})

# refetch

Fetch the query again, optionally with new variables:

this.$apollo.queries.users.refetch()
// With new variables
this.$apollo.queries.users.refetch({
  friendsOf: 'id-user'
})

# setVariables

Update the variables on the query and refetch it if they have changed. To force a refetch, use refetch.

this.$apollo.queries.users.setVariables({
  friendsOf: 'id-user'
})

# setOptions

Update the Apollo watchQuery options and refetch:

this.$apollo.queries.users.setOptions({
  fetchPolicy: 'cache-and-network'
})

# startPolling

Start an auto update using polling (which means refetching every x ms):

this.$apollo.queries.users.startPolling(2000) // ms

# stopPolling

Stop the polling:

this.$apollo.queries.users.stopPolling()