useStreamJSON

Hook which takes a http://, https:// or file:/// URL pointing to a JSON resource, caches it to the command's support folder, and streams through its content. Useful when dealing with large JSON arrays which would be too big to fit in the command's memory.

Signature

export function useStreamJSON<T, U>(
  url: RequestInfo,
  options: RequestInit & {
    filter?: (item: T) => boolean;
    transform?: (item: any) => T;
    pageSize?: number;
    initialData?: U;
    keepPreviousData?: boolean;
    execute?: boolean;
    onError?: (error: Error) => void;
    onData?: (data: T) => void;
    onWillExecute?: (args: [string, RequestInit]) => void;
  },
): AsyncState<Result<T>> & {
  revalidate: () => void;
};

Arguments

• url - The RequestInfo describing the resource that needs to be fetched. Strings starting with http://, https:// and Request objects will use fetch, while strings starting with file:/// will be copied to the cache folder.

With a few options:

• options extends RequestInit allowing you to specify a body, headers, etc. to apply to the request.

• options.pageSize the amount of items to fetch at a time. By default, 20 will be used

• options.dataPath is a string or regular expression informing the hook that the array (or arrays) of data you want to stream through is wrapped inside one or multiple objects, and it indicates the path it needs to take to get to it.

• options.transform is a function called with each top-level object encountered while streaming. If the function returns an array, the hook will end up streaming through its children, and each array item will be passed to options.filter. If the function returns something other than an array, it will be passed to options.filter. Note that the hook will revalidate every time the filter function changes, so you need to use useCallback to make sure it only changes when it needs to.

• options.filter is a function called with each object encountered while streaming. If it returns true, the object will be kept, otherwise it will be discarded. Note that the hook will revalidate every time the filter function changes, so you need to use useCallback to make sure it only changes when it needs to.

Including the useCachedPromise's options:

• options.keepPreviousData is a boolean to tell the hook to keep the previous results instead of returning the initial value if there aren't any in the cache for the new arguments. This is particularly useful when used for data for a List to avoid flickering.

Including the useCachedState's options:

• options.initialData is the initial value of the state if there aren't any in the Cache yet.

Including the usePromise's options:

• options.execute is a boolean to indicate whether to actually execute the function or not. This is useful for cases where one of the function's arguments depends on something that might not be available right away (for example, depends on some user inputs). Because React requires every hook to be defined on the render, this flag enables you to define the hook right away but wait until you have all the arguments ready to execute the function.

• options.onError is a function called when an execution fails. By default, it will log the error and show a generic failure toast with an action to retry.

• options.onData is a function called when an execution succeeds.

• options.onWillExecute is a function called when an execution will start..

Return

Returns an object with the AsyncState corresponding to the execution of the fetch as well as a couple of methods to manipulate it.

• data, error, isLoading - see AsyncState.

• pagination - the pagination object that Raycast Lists and Grids expect.

• revalidate is a method to manually call the function with the same arguments again.

• mutate is a method to wrap an asynchronous update and gives some control over how the hook's data should be updated while the update is going through. By default, the data will be revalidated (eg. the function will be called again) after the update is done. See Mutation and Optimistic Updates for more information.

Example

import { Action, ActionPanel, List, environment } from "@raycast/api";
import { useStreamJSON } from "@raycast/utils";
import { join } from "path";
import { useCallback, useState } from "react";

type Formula = { name: string; desc?: string };

export default function Main(): JSX.Element {
  const [searchText, setSearchText] = useState("");

  const formulaFilter = useCallback(
    (item: Formula) => {
      if (!searchText) return true;
      return item.name.toLocaleLowerCase().includes(searchText);
    },
    [searchText],
  );

  const formulaTransform = useCallback((item: any): Formula => {
    return { name: item.name, desc: item.desc };
  }, []);

  const { data, isLoading, pagination } = useStreamJSON("https://formulae.brew.sh/api/formula.json", {
    initialData: [] as Formula[],
    pageSize: 20,
    filter: formulaFilter,
    transform: formulaTransform
  });

  return (
    <List isLoading={isLoading} pagination={pagination} onSearchTextChange={setSearchText}>
      <List.Section title="Formulae">
        {data.map((d) => (
          <List.Item key={d.name} title={d.name} subtitle={d.desc} />
        ))}
      </List.Section>
    </List>
  );
}

Mutation and Optimistic Updates

In an optimistic update, the UI behaves as though a change was successfully completed before receiving confirmation from the server that it was - it is being optimistic that it will eventually get the confirmation rather than an error. This allows for a more responsive user experience.

You can specify an optimisticUpdate function to mutate the data in order to reflect the change introduced by the asynchronous update.

When doing so, you can specify a rollbackOnError function to mutate back the data if the asynchronous update fails. If not specified, the data will be automatically rolled back to its previous value (before the optimistic update).

import { Action, ActionPanel, List, environment } from "@raycast/api";
import { useStreamJSON } from "@raycast/utils";
import { join } from "path";
import { useCallback, useState } from "react";
import { setTimeout } from "timers/promises";

type Formula = { name: string; desc?: string };

export default function Main(): JSX.Element {
  const [searchText, setSearchText] = useState("");

  const formulaFilter = useCallback(
    (item: Formula) => {
      if (!searchText) return true;
      return item.name.toLocaleLowerCase().includes(searchText);
    },
    [searchText],
  );

  const formulaTransform = useCallback((item: any): Formula => {
    return { name: item.name, desc: item.desc };
  }, []);

  const { data, isLoading, mutate, pagination } = useStreamJSON("https://formulae.brew.sh/api/formula.json", {
    initialData: [] as Formula[],
    pageSize: 20,
    filter: formulaFilter,
    transform: formulaTransform,
  });

  return (
    <List isLoading={isLoading} pagination={pagination} onSearchTextChange={setSearchText}>
      <List.Section title="Formulae">
        {data.map((d) => (
          <List.Item
            key={d.name}
            title={d.name}
            subtitle={d.desc}
            actions={
              <ActionPanel>
                <Action
                  title="Delete All Items But This One"
                  onAction={async () => {
                    mutate(setTimeout(1000), {
                      optimisticUpdate: () => {
                        return [d];
                      },
                    });
                  }}
                />
              </ActionPanel>
            }
          />
        ))}
      </List.Section>
    </List>
  );
}

Types

AsyncState

An object corresponding to the execution state of the function.

// Initial State
{
  isLoading: true, // or `false` if `options.execute` is `false`
  data: undefined,
  error: undefined
}

// Success State
{
  isLoading: false,
  data: T,
  error: undefined
}

// Error State
{
  isLoading: false,
  data: undefined,
  error: Error
}

// Reloading State
{
  isLoading: true,
  data: T | undefined,
  error: Error | undefined
}