Quick start

Search…
Quick start
Quick start
​Install the JavaScript module from the NPM registry.
1
npm i @stamp/it
2
# or
3
npm i stampit
Copied!
Create an empty stamp.
1
const stampit = require('@stamp/it')
2
​
3
let Stamp = stampit() // creates new stamp
Copied!
​Compose it with another stamp.
1
const HasLog = require('./HasLog')
2
​
3
Stamp = Stamp.compose(HasLog) // creates a new stamp composed from the two
Copied!
Add default properties to it.
1
Stamp = Stamp.props({ // creates a new derived stamp
2
  S3: require('aws-sdk').S3
3
})
Copied!
Add an initializer (aka constructor).
1
Stamp = Stamp.init(function ({ bucket }, { stamp }) { // creates a new derived stamp
2
  this.s3instance = new this.S3({ 
3
    apiVersion: '2006-03-01', 
4
    params: { Bucket: bucket || stamp.compose.configuration.bucket } // using configuration.bucket, see below
5
  })
6
})
Copied!
Add a method.
1
Stamp = Stamp.methods({ // creates a new derived stamp
2
  upload({ fileName, stream }) {
3
    this.log.info({ fileName }, 'Uploading file') // .log property from the HasLog stamp
4
​
5
    return this.s3instance.upload({ Key: fileName, Body: stream }).promise() // see above
6
  }
7
})
Copied!
Add a configuration.
1
Stamp = Stamp.conf({ // creates a new derived stamp
2
  bucket: process.env.UPLOAD_BUCKET
3
})
Copied!
Add a static method.
1
Stamp = Stamp.statics({ // creates a new derived stamp
2
  setDefaultBucket(bucket) {
3
    return this.conf({ bucket })
4
  }
5
})
Copied!
Make the .s3instance , .log, and .S3 properties private.
1
const Privatize = require('@stamp/privatize')
2
​
3
Stamp = Stamp.compose(Privatize) // creates a new derived stamp
Copied!
Give it a proper name.
1
const FileStore = Stamp.compose({ name: 'FileStore' })
Copied!
Create objects from your stamp.
1
const store = FileStore()
Copied!
Shorter API
Here is the same FileStore stamp but written in a more concise way.
S3FileStore.js
1
const HasLog = require('./HasLog')
2
const Privatize = require('@stamp/privatize')
3
​
4
const FileStore = HasLog.compose(Privatize, {
5
  name: 'FileStore',
6
  props: {
7
    S3: require('aws-sdk').S3
8
  },
9
  init({ bucket }, { stamp }) {
10
    this.s3instance = new this.S3({ 
11
      apiVersion: '2006-03-01', 
12
      params: { Bucket: bucket || stamp.compose.configuration.bucket }
13
    })
14
  },
15
  methods: {
16
    upload({ fileName, stream }) {
17
      this.log.info({ fileName }, 'Uploading file')
18
      return this.s3instance.upload({ Key: fileName, Body: stream }).promise()
19
    }
20
  },
21
  conf: {
22
    bucket: process.env.UPLOAD_BUCKET
23
  },
24
  statics: {
25
    setDefaultBucket(bucket) {
26
      return this.conf({ bucket })
27
    }
28
  }
29
})
Copied!
The reusable HasLog stamp can be implemented in the following way.
HasLog.js
1
module.exports = require('@stamp/it')({
2
  init(_, { stamp }) {
3
    // this will reuse the stamp name "FileStore" we set above
4
    this.log = require('bunyan').createLogger({ name: stamp.name })
5
  }
6
})
Copied!
Using the stamp
Use your stamp ad-hoc.
1
async function uploadTo(req, res) {
2
  const fileStore = FileStore({ bucket: req.params.bucket }) // create instance
3
​
4
  await fileStore.upload({ fileName: req.query.file, stream: req }) // use the method of the stamp
5
​
6
  res.sendStatus(201)
7
}
Copied!
Or preconfigure it.
1
const CatGifStore = FileStore.setDefaultBucket('cat-gifs') // pre-configuring the bucket name
2
​
3
const catGifStore = CatGifStore() // create an instance of the store
4
​
5
await catGifStore.upload({ fileName: 'cat.gif', stream: readableStream })
Copied!
If you want to silence the shameful fact that you are collecting cat gifs then here is how you disable log. Just overwrite the log property with a silent one.
1
const SilentCatGifStore = CatGifStore.props({
2
  log: {
3
    info() {} // silence!
4
  }
5
})
6
​
7
await SilentCatGifStore().upload({ fileName: 'cat.gif', stream: readableStream })
Copied!
Alternatively, you can have a generic silent logger stamp. Compose with it to override the HasLog.
1
const HasSilentLog = stampit.props({ log: { info: () => {} } })
2
​
3
const SilentCatGifStore = CatGifStore.compose(HasSilentLog)
Copied!
The new keyword also works with any stamp.
1
const catGifStore = new CatGifStore()
Copied!
Another way to create an object is to use .create() static method.
1
const catGifStore = CatGifStore.create()
Copied!
Mocking I/O in unit tests
Replacing actual S3 with a fake one.
1
const MockedFileStore = FileStore.props({
2
  S3() {
3
    return {
4
      upload() {
5
        return { promise() { return Promise.resolve() } }
6
      }
7
  }
8
})
9
​
10
// Same as above but a one-liner:
11
​
12
const MockedFileStore = FileStore.props({
13
  S3: () => ({ upload: () => ({ async promise() {} }) })
14
})
Copied!
Basic API
Head to the Basics page to view more API documentation. However, by now you already know all you need.
Essentials - Previous
FAQ
Next - API
Basics
Last modified 3yr ago
Copy link
Contents
Quick start
Shorter API
Using the stamp
Mocking I/O in unit tests
Basic API