@cerebral/http

Install 

NPM

npm install @cerebral/http

Description 

The HTTP provider exposes the ability to do HTTP requests both in actions and directly in signals. It supports cors and file upload, with progress handling. It default to json, but you can configure it to whatever you want.

Read more about http in the Cerebral in depth - Http article.

import { set } from 'cerebral/operators'
import { httpGet } from '@cerebral/http/operators'
import { state, props, string } from 'cerebral/tags'

export default [
  httpGet(string`/items/${props`itemKey`}`),
  set(state`app.currentItem`, props`result`)
]

All factories of HTTP provider supports template tags.

Instantiate 

import { Controller, Module } from 'cerebral'
import HttpProvider from '@cerebral/http'

const http = HttpProvider({
  // Prefix all requests with this url
  baseUrl: 'https://api.github.com',

  // Any default headers to pass on requests
  headers: {
    'Content-Type': 'application/json; charset=UTF-8',
    Accept: 'application/json'
  },

  // When talking to cross origin (cors), pass cookies
  // if set to true
  withCredentials: false,

  // Provide a global request timeout for all calls
  // which can be overwritten for request by providing
  // a different timeout when doing a request
  // in actions or operators
  timeout: 5000
})

const app = Module({
  providers: { http }
})

const controller = Controller(app)

You can update these default options in an action:

function updateDefaultHttpOptions({ http }) {
  http.updateOptions({
    // Updated options
  })
}

abort 

You can abort any running request, causing the request to resolve as status code 0 and sets the type to abort on the error object.

function searchItems({ input, state, path, http }) {
  http.abort('/items*') // regexp string
  return http
    .get(`/items?query=${input.query}`)
    .then(path.success)
    .catch((error) => {
      if (error.type === 'abort') {
        return path.abort()
      }

      return path.error({ error })
    })
}

export default [
  searchItems,
  {
    success: [],
    error: [],
    abort: []
  }
]

cors 

Cors has been turned into a “black box” by jQuery. Cors is actually a very simple concept, but due to a lot of confusion of “Request not allowed”, cors has been an option to help out. In HttpProvider we try to give you the insight to understand how cors actually works.

Cors has nothing to do with the client. The only client configuration related to cors is the withCredentials option, which makes sure cookies are passed to the cross origin server. The only requirement for cors to work is that you pass the correct Content-Type. Now, this depends on the server in question. Some servers allows any content-type, others require a specific one. These are the typical ones:

  • text/plain
  • application/x-www-form-urlencoded
  • application/json; charset=UTF-8

Note that this is only related to the request. If you want to define what you want as response, you set the Accept header, which is application/json by default.

errors 

HttpProviderError 

import {HttpProviderError} from '@cerebral/http'

// Error structure
{
  name: 'HttpProviderError',
  type: 'http | abort | timeout',
  message: 'Some error message or responseText',
  response: {
    result: {}, // Parsed responseText
    headers: {},
    status: 200
  },
  stack: '...'
}

This error is available in the following scenarios:

  • Inside an action
function someAction ({http}) {
  return http.get('/something').catch(error => ...)
}
  • Going down an error path
;[
  httpGet('/something'),
  {
    success: [],
    error: [
      // {error: ...}
    ]
  }
]
  • To module catch handlers
const errorCatched = [
  // {error: ...}
  displayError
]

Module({
  catch: [[HttpProviderError, errorCatched]]
})

delete 

action 

function someDeleteAction({ http }) {
  const query = {}
  const options = {}

  return http
    .delete('/items/1', query, options)
    .then((response) => {
      return { response }
    })
    .catch((error) => {
      return { error }
    })
}

operator 

import { httpDelete } from '@cerebral/http/operators'
import { state } from 'cerebral/tags'

export default [
  httpDelete(string`/items/${state`currentItemId`}`)
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]

operator with paths 

import { httpDelete } from '@cerebral/http/operators'
import { state } from 'cerebral/tags'

export default [
  httpDelete(string`/items/${state`currentItemId`}`),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],
    timeout: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

get 

action 

function someGetAction({ http }) {
  const query = {}
  const options = {}

  return http
    .get('/items', query, options)
    .then((response) => {
      return { someResponse: response }
    })
    .catch((error) => {
      return { someError: error }
    })
}

operator 

import { httpGet } from '@cerebral/http/operators'

export default [
  httpGet('/items')
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]

On error this will throw to the signal or global catch handler.

operator with paths 

import { httpGet } from '@cerebral/http/operators'

export default [
  httpGet('/items'),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],
    timeout: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

patch 

action 

function somePatchAction({ http }) {
  const data = {}
  const options = {}

  return http
    .patch('/items/1', data, options)
    .then((response) => {
      return { response }
    })
    .catch((error) => {
      return { error }
    })
}

operator 

import { httpPatch } from '@cerebral/http/operators'
import { state, props, string } from 'cerebral/tags'

export default [
  httpPatch(string`/items/${props`itemId`}`, state`patchData`)
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]

operator with paths 

import { httpPatch } from '@cerebral/http/operators'
import { state, props, string } from 'cerebral/tags'

export default [
  httpPatch(string`/items/${props`itemId`}`, state`patchData`),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],
    timeout: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

post 

action 

function somePostAction({ http }) {
  const data = {}
  const options = {}

  return http
    .post('/items', data, options)
    .then((response) => {
      return { response }
    })
    .catch((error) => {
      return { error }
    })
}

operator 

import { httpPost } from '@cerebral/http/operators'
import { props } from 'cerebral/tags'

export default [
  httpPost('/items', {
    title: props`itemTitle`,
    foo: 'bar'
  })
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]

operator with paths 

import { httpPost } from '@cerebral/http/operators'
import { props } from 'cerebral/tags'

export default [
  httpPost('/items', {
    title: props`itemTitle`,
    foo: 'bar'
  }),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],
    timeout: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

put 

action 

function somePutAction({ http }) {
  const data = {}
  const options = {}

  return http
    .put('/items/1', data, options)
    .then((response) => {
      return { response }
    })
    .catch((error) => {
      return { error }
    })
}

operator 

import { httpPut } from '@cerebral/http/operators'

export default [
  httpPut('/items', {
    // data object
  })
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]

operator with paths 

import { httpPut } from '@cerebral/http/operators'

export default [
  httpPut('/items', {
    // data object
  }),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],
    timeout: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

responses 

There are two types of responses from the HTTP provider. A response and an error of type HttpProviderError. A response will be received on status codes 200-299. Everything else is an error.

response 

{
  result: 'the response body',
  headers: {...},
  status: 200
}

error 

{
  name: 'HttpProviderError',
  type: 'http | abort | timeout',
  message: 'Some potential error message',
  result: 'Message or response body',
  status: 500,
  headers: {},
  stack: '...'
}

request 

function someGetAction ({http}) {
  return http.request({
    // Any http method
    method: 'GET',

    // Url you want to request to
    url: '/items'

    // Request body as object. Will automatically be stringified if json and
    // urlEncoded if application/x-www-form-urlencoded
    body: {},

    // Query as object, will automatically be urlEncoded
    query: {},

    // If cross origin request, pass cookies
    withCredentials: false,

    // Any additional http headers, or overwrite default
    headers: {},

    // A function or signal path (foo.bar.requestProgressed) that
    // triggers on request progress. Passes {progress: 45} etc.
    onProgress: null
  })
}

uploadFile 

action 

function someDeleteAction({ http, props }) {
  return http
    .uploadFile('/upload', props.files, {
      name: 'filename.png', // Default to "files"
      data: {}, // Additional form data
      headers: {},
      onProgress: 'some.signal.path' // Upload progress
    })
    .then((response) => {
      return { response }
    })
    .catch((error) => {
      return { error }
    })
}

operator 

import { httpUploadFile } from '@cerebral/http/operators'
import { state, props } from 'cerebral/tags'

export default [
  httpUploadFile('/uploads', props`file`, {
    name: state`currentFileName`
  }),
  {
    success: [
      /* PROPS: {response: {...}} */
    ],
    error: [
      /* PROPS: {error: {...}} */
    ],
    abort: [
      /* PROPS: {error: {...}} */
    ],

    // Optionally any status code, ex. 404: []
    '${STATUS_CODE}': [
      /* PROPS: {response/error: {...}} */
    ]
  }
]

operator with paths 

import { httpUploadFile } from '@cerebral/http/operators'
import { state, props } from 'cerebral/tags'

export default [
  httpUploadFile('/uploads', props`file`, {
    name: state`currentFileName`
  })
  /*
                            PROPS: {
                              response: {...}
                            }
                          */
]