Hook to subscribe to request state updates.

useLazyRequest accepts an asyncRequest function that returns some value. As the asyncRequest function runs, requestState change.

It is free dependencies library, that easy in usages and does not required wrappers

Install

By using npm on yarn:

npm install request-react-hooks

yarn add request-react-hooks

Example usage:

Pass an asyncRequest function to the hook and subscribe to requestState updates:

import { useLazyRequest } from 'request-react-hooks'

const asyncRequest = async (parameter: number): Promise<string> => {
  await requestToBackend()
  return 'its result ' + String(parameter)
}

const MyAsyncComponent = () => {
  const [requestState, lazyRequest] = useLazyRequest(asyncRequest)

  useEffect(() => {
    lazyRequest(1111)
  }, [])

  const { loading, value, error } = requestState

  // will return on render:
  // { loading: false, value: null, error: null }
  // { loading: true, value: null, error: null }
  // { loading: false, value: 'its result 1111', error: null }
  console.log(requestState)

  if (loading) {
    return <p>Loading...</p>
  } else if (error) {
    return <p>Error!</p>
  } else {
    return <p>{value}</p>
  }
}

Returned types

Be sure to specify the types of parameters and return values for the asyncRequest, passed to the hook.

Otherwise, the compiler will not know what value is in the requestState and with what it will be possible to call lazyRequest

import {
  ActionCreators,
  LazyRequest,
  RequestState,
  UseLazyRequestResult,
} from 'request-react-hooks'

type Params = { par1: string; par2: string }
type Result = { result1: string; result2: number }

const asyncRequest = async (params: Params): Promise<Result> => {
  await requestToBackend()
  return { result1: params.par1, result2: params.par2 }
}

const initialState: Result<Result> = {
  value: { result1: 'initial_value_1', result2: 'initial_value_2' },
  error: null,
  loading: false,
}

// type UseLazyRequestResult<typeof asyncRequest> = [
//   RequestState<Result>,
//   LazyRequest<typeof asyncRequest>,
//   ActionCreators<Result>
// ]
const useLazyResult: UseLazyRequestResult<typeof asyncRequest> = useLazyRequest(
  asyncRequest,
  initialState,
)

// type RequestState<Result> = {
//   value: Result | null,
//   loading: boolean,
//   error: Record<string, any>
// }
const state: RequestState<Result> = useLazyResult[0]

// interface LazyRequest<typeof asyncRequest> {
//  (args: Parameters<typeof asyncRequest>): Promise<Result | undefined>
// }
const lazyRequest: LazyRequest<typeof asyncRequest> = useLazyResult[1]

// type ActionCreators<Result> = {
//   setValue: (value: Result | null) => void
//   setLoading: (loading: boolean) => void,
//   setError: (error: Record<string, any> | null) => void
//   clearState: () => void
// }
const actions: ActionCreators<Result> = useLazyResult[2]

Request exception handling

If the lazyRequest function fails, an error state will be written to the requestState

const asyncRequest = async (parameter: string): Promise<string> => {
  await requestToBackend()

  if (parameter === 'invalid parameter') {
    throw { text: 'passed invalid parameter', status: 1001 }
  }

  return 'its result ' + parameter
}

const [requestState, lazyRequest] = useLazyRequest(asyncRequest)

useEffect(() => {
  lazyRequest('invalid parameter')
}, [])

// will return on render:
// { loading: false, value: null, error: null }
// { loading: true, value: null, error: null }
// {
//   loading: false,
//   value: null,
//   error: {
//     text: 'passed invalid parameter',
//     status: 1001,
//   }
// }
console.log(requestState)

Use all possibilities of useLazyRequest

import { useCallback } from 'react'
import { RequestState, useLazyRequest } from 'request-react-hooks'

type Result = string

const request = async (par1: string, par2: string): Promise<Result> => {
  await requestToBackend()
  return 'its result ' + par1 + par2
}

const initialState: RequestState<Result> = {
  value: 'initial_value',
  error: null,
  loading: false,
}

const Component = () => {
  const [requestState, lazyRequest, actions] = useLazyRequest(
    request,
    initialState,
  )

  const { loading, value, error } = requestState

  const handleReload = useCallback(() => {
    lazyRequest('value_1', 'value_2')
  }, [lazyRequest])

  // After click on reload button, user will see the disabled button
  // and error message, because clear error in state will be after succes
  // execute request
  if (error) {
    return (
      <>
        <p>Error!</p>

        <button onClick={handleReload} disabled={loading}>
          upload again
        </button>
      </>
    )
  }

  if (loading) {
    return <p>Loading</p>
  }

  // This is the first thing the user sees
  // because we passed initial values in state.
  // After click on reload button, user will see loading message,
  // because handling of load case happens before that case is handled
  return (
    <>
      <p>{value}</p>

      <button onClick={handleReload}>clear state and reload</button>
    </>
  )
}

More examples usage

• Get items by user click
• Get items by component mount
• Handle user input