@cerebral/http/README.md

HTTP provider for Cerebral 2

# @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](https://www.jsblog.io/articles/christianalfoni/cerebral_in_depth_http) article.

```js
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

```js
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:

```js
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.

```js
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

```js
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

```js
function someAction ({http}) {
  return http.get('/something').catch(error => ...)
}
```

* Going down an error path

```js
;[
  httpGet('/something'),
  {
    success: [],
    error: [
      // {error: ...}
    ]
  }
]
```

* To module catch handlers

```js
const errorCatched = [
  // {error: ...}
  displayError
]

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

## delete

### action

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

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

### operator

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

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

### operator with paths

```js
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

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

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

### operator

```js
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

```js
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

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

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

### operator

```js
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

```js
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

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

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

### operator

```js
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

```js
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

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

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

### operator

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

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

### operator with paths

```js
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

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

### error

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

## request

```js
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

```js
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

```js
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

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

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