npm package: @neoxia-js/multer-azure
Description: Streaming multer storage engine for Azure Blob storage. Forked from multer-azure
Author: Alex McKenzie
Latest version: 1.0.0

# Multer Azure
This is a multer storage engine for Azure's blob storage.

## Installation
```sh
yarn add @neoxia-js/multer-azure
```

## Usage
```javascript
var express = require('express')
var multer = require('multer')
var multerAzure = require('multer-azure')

var app = express()

var upload = multer({ 
  storage: multerAzure({
    connectionString: '[Azure Storage Connection String]', //Connection String for azure storage account, this one is prefered if you specified, fallback to account and key if not.
    account: '[Azure Storage Account]', //The name of the Azure storage account
    key: '[Azure Storage Account Key]', //A key listed under Access keys in the storage account pane
    container: '[Blob Container Name]'  //Any container name, it will be created if it doesn't exist
    blobPathResolver: function(req, file, callback){
      var blobPath = yourMagicLogic(req, file); //Calculate blobPath in your own way.
      callback(null, blobPath);
    }
  })
})

app.post('/', upload.any(), function (req, res, next) {
  console.log(req.files)
  res.status(200).send('Uploaded: ' + req.files)
})
```

### File Information
`multer-azure` will return the following information in each file in the `req.files` parameter:

Key|Description
---|---
`fieldname`| The field name/key sent in the post request with the image.
`originalname`| The full original name of the file.
`encoding`| The file encoding.
`mimetype`| The MIME type of the file.
`filename`| The file name in the azure storage.
`container` | The azure storage container where the file upload to.
`blobPath` | The full blobName (or we call it blobPath).
`url` | The full url of the file just got uploaded.

### File Naming

Files in an Azure container have to have a unique name. `multer-azure` allows you to customize the blobPath.

Simply provide a blobPathResolver, the same way as what you do with multer.diskStorage.

```javascript
    blobPathResolver: function(req, file, callback){
      var blobPath = yourMagicLogic(req, file);//Calculate blobPath in your own way.
      callback(null, blobPath);
    }
```

If you don't provide a blobPathResolver, a default file name is generated:

`Date.now()` + `encodeURIComponent(new Buffer([FILENAME]).toString('base64'))` + extension.

This results in a url safe filename that looks like `"1480994807566-Qmx1ZVBUQ0xvZ29MQVJHRTIwMTYuanBn.jpg"`, which is most likely overkill.

### Azure Requirements

The `connectionString` will be prefered if you pass it, otherwise please provide account and key.

The `account` is just the name of your storage account that you've created in Azure. For information on how to do this, check out [this tutorial.](https://docs.microsoft.com/en-us/azure/storage/storage-create-storage-account#create-a-storage-account)

The `key` for the key field can be obtained under the **Access keys** section in the storage account pane in Azure.

The `container` name can be anything you choose, as long as it's unique to the storage account and as long as it fits Azure's naming restrictions. If the container does not exist the storage engine will create it.