angular-material-datatransfer-lib

Demo: https://niklr.github.io/angular-material-datatransfer/

angular-material-datatransfer-lib is a library combining the upload and download of multiple simultaneous files in a unified user interface. The library is explicitly designed for modern browsers supporting advanced HTML5 File API features.

The unified user interface is built on top of Google's Material Design implemented by Angular Material using Angular. Material Design by Google's definition is a visual language that synthesizes the classic principles of good design with the innovation and possibility of technology and science.

For multiple simultaneous uploads the open-source library called Resumable.js is used. Resumable.js introduces fault-tolerance into the upload of large files through HTTP. This is done by splitting each file into small chunks. Then, whenever the upload of a chunk fails, uploading is retried until the procedure completes. This allows uploads to automatically resume uploading after a network connection is lost either locally or to the server. Additionally, it allows for users to pause, resume and even recover uploads without losing state because only the currently uploading chunks will be aborted, not the entire upload.

For multiple simultaneous downloads the open-source library called FileSaver.js is used. FileSaver.js implements the saveAs() FileSaver interface in browsers that do not natively support it.

Table of Content:

• Basic setup
• Handling download
• Events
• Configuration
• Server-side setup
• Building

Basic setup

A sample implementation can be found here. It was created with ng new example1 of Angular CLI.

In order to add this library to your project, follow the steps below:

1. npm install angular-material-datatransfer-lib --save
2. Add the dependencies listed in peerDependencies (node_modules/angular-material-datatransfer-lib/package.json) to the dependencies in your package.json
3. npm install
4. Extend your angular.json by appending the following lines after the global styles build entry.

1"styles": [
2    ...
3],
4"stylePreprocessorOptions": {
5    "includePaths": [
6        "node_modules"
7    ]
8},
9"scripts": [
10    ...
11]

5. Add angular-material.scss to your src folder (if it does not exist already).
6. Add a folder called style in the src folder with the following files

• angular-material-theme.scss
• app.scss

7. Append the following lines in src/styles.scss

1@import 'angular-material.scss';
2@import 'style/app.scss';

8. Include Material Icons in the header of index.html

1<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">

9. Extend app.module.ts by importing AngularMaterialDatatransferModule and AngularMaterialDatatransferComponent

1import { BrowserModule } from '@angular/platform-browser';
2import { NgModule } from '@angular/core';
3import { AngularMaterialDatatransferModule, AngularMaterialDatatransferComponent } from 'angular-material-datatransfer-lib';
4
5import { AppRoutingModule } from './app-routing.module';
6import { AppComponent } from './app.component';
7
8@NgModule({
9  declarations: [AppComponent],
10  imports: [
11    BrowserModule,
12    AppRoutingModule,
13    AngularMaterialDatatransferModule
14  ],
15  providers: [AngularMaterialDatatransferComponent],
16  bootstrap: [AppComponent]
17})
18export class AppModule { }

10. Add the library to one of your components e.g. app.component.html

1<angular-material-datatransfer-lib>Loading...</angular-material-datatransfer-lib>

11. Initialize the library

1import { Component, ViewChild, AfterViewInit } from '@angular/core';
2import { AngularMaterialDatatransferComponent } from 'angular-material-datatransfer-lib';
3
4@Component({
5  selector: 'app-root',
6  templateUrl: './app.component.html',
7  styleUrls: ['./app.component.scss']
8})
9export class AppComponent implements AfterViewInit {
10  @ViewChild(AngularMaterialDatatransferComponent, {static: false}) amdComponent: AngularMaterialDatatransferComponent;
11
12  constructor() {
13  }
14
15  ngAfterViewInit(): void {
16    setTimeout(() => {
17      const config = {
18        core: {
19          showUploadDropzone: true,
20          paginationRppOptions: [5, 10, 25],
21          preprocessHashEnabled: true,
22          preprocessHashChecked: false
23        },
24        resumablejs: {
25          simultaneousUploads: 2,
26          preprocess: function (chunk) {
27            // do something with the chunk
28            chunk.preprocessFinished();
29          }
30        }
31      };
32      this.amdComponent.create(config);
33    }, 10);
34  }
35
36}

Handling download

The download of a file can be triggered by invoking the download function with the following arguments:

• filename The name of the file to be downloaded.
• url The URL of the file to be downloaded.
• size The size in bytes of the file to be downloaded.

1this.amdComponent.download(filename, url, size);

Events

After initialization, it is possible to listen to events initiated by angular-material-datatransfer:

1document.addEventListener('github:niklr/angular-material-datatransfer.upload-completed', function (e) { ... });

• github:niklr/angular-material-datatransfer.upload-completed Indicates that the overall upload has been completed.
• github:niklr/angular-material-datatransfer.download-completed Indicates that the overall download has been completed.
• github:niklr/angular-material-datatransfer.item-added Indicates that an item has been added. It will be passed a IDatatransferItem as detail payload.
• github:niklr/angular-material-datatransfer.item-removed Indicates that an item has been removed. It will be passed a IDatatransferItem as detail payload.
• github:niklr/angular-material-datatransfer.item-completed Indicates that an item has been completed.
• github:niklr/angular-material-datatransfer.items-cleared Indicates that all items have been cleared.

Configuration

In order to initialize and configure angular-material-datatransfer, a custom event called github:niklr/angular-material-datatransfer.create can be dispatched on the document object. The configuration differentiates between core and resumablejs. Both are described below.

1var config = {
2  production: boolean // corresponds to the environment variable (Default: true)
3  core: {
4    ...
5  },
6  resumablejs: {
7    ...
8  }
9};
10var event = new CustomEvent('github:niklr/angular-material-datatransfer.create', { 'detail': config });
11document.dispatchEvent(event);

Core configuration

• showUploadDropzone Indicates if the built-in dropzone element enabling the user to drop folders/files to be uploaded should be shown. (Default: 'true')
• uploadBrowseElementId The identifier of the element enabling the user to add files to be uploaded. (Default: undefined)
• uploadDropElementId The identifier of the element enabling the user to drop folders/files to be uploaded. (Default: undefined)
• paginationRppOptions The pagination options containing the numbers defining how many results should be shown per page. (Default: [5, 10, 25])
• simultaneousDownloads Number of simultaneous downloads. (Default: 2)
• downloadMethod HTTP method to use when downloading from the server (GET, POST, PUT, PATCH). (Default: GET)
• downloadHeaders Extra headers to include in the multipart POST with data. This can be an object or a function that allows you to construct and return a value, based on supplied file (Default: {})
• downloadWithCredentials Standard CORS requests used for downloading do not send or set any cookies by default. In order to include cookies as part of the request, you need to set the property to true. (Default: false)
• downloadXhrTimeout The timeout in milliseconds for each download request (Default: 0)
• preprocessHashEnabled Indicates if the built-in preprocess hash module should be enabled. (Default: 'false')
• preprocessHashChecked Indicates if the checkbox for the built-in preprocess hash module should be checked. (Default: 'true')
• preprocessHashTarget The target URL for the GET request to the server for each file to see if it already exists based on the in-browser calculated hash. This can be a string or a function that allows you you to construct and return a value, based on supplied params. (Default: https://httpbin.org)
• preprocessHashMethod HTTP method to use when sending file preprocess hash requests. (Default: 'GET')
• preprocessHashParameterName The name of the preprocess hash request parameter for the hash. (Default: 'hash')
• preprocessHashFileNameParameterName The name of the preprocess hash request parameter for the file name. (Default: 'filename')
• preprocessHashFunctionName The name of the hash function to be used in the built-in preprocess hash module. (sha1, md5) (Default: 'sha1')
• preprocessHashEncodingName The name of the encoding scheme to be used in the built-in preprocess hash module. (latin1, hex, base64, utf8) (Default: 'hex')
• preprocessHashInputEncodingName The name of the input encoding scheme to be used in the built-in preprocess hash module. (latin1, hex, base64, utf8) (Default: 'latin1')
• preprocessHashTooltipContent The text to explain the preprocess option in a tooltip. (Default: 'The preprocess option checks if the file is already on the system before uploading.')
• parseMessageCallback A function which displays the status message of an uploaded item. (Default: displays the raw result of an uploaded item as returned by the API endpoint)

Resumablejs configuration

• target The target URL for the multipart POST request. This can be a string or a function that allows you you to construct and return a value, based on supplied params. (Default: https://httpbin.org)
• testTarget The target URL for the GET request to the server for each chunk to see if it already exists. This can be a string or a function that allows you you to construct and return a value, based on supplied params. (Default: null)
• chunkSize The size in bytes of each uploaded chunk of data. The last uploaded chunk will be at least this size and up to two the size, see Issue #51 for details and reasons. (Default: 1*1024*1024)
• forceChunkSize Force all chunks to be less or equal than chunkSize. Otherwise, the last chunk will be greater than or equal to chunkSize. (Default: false)
• simultaneousUploads Number of simultaneous uploads (Default: 3)
• fileParameterName The name of the multipart request parameter to use for the file chunk (Default: file)
• chunkNumberParameterName The name of the chunk index (base-1) in the current upload POST parameter to use for the file chunk (Default: resumableChunkNumber)
• totalChunksParameterName The name of the total number of chunks POST parameter to use for the file chunk (Default: resumableTotalChunks)
• chunkSizeParameterName The name of the general chunk size POST parameter to use for the file chunk (Default: resumableChunkSize)
• totalSizeParameterName The name of the total file size number POST parameter to use for the file chunk (Default: resumableTotalSize)
• identifierParameterName The name of the unique identifier POST parameter to use for the file chunk (Default: resumableIdentifier)
• fileNameParameterName The name of the original file name POST parameter to use for the file chunk (Default: resumableFilename)
• relativePathParameterName The name of the file's relative path POST parameter to use for the file chunk (Default: resumableRelativePath)
• currentChunkSizeParameterName The name of the current chunk size POST parameter to use for the file chunk (Default: resumableCurrentChunkSize)
• typeParameterName The name of the file type POST parameter to use for the file chunk (Default: resumableType)
• query Extra parameters to include in the multipart request with data. This can be an object or a function. If a function, it will be passed a ResumableFile and a ResumableChunk object (Default: {})
• testMethod Method for chunk test request. (Default: 'GET')
• uploadMethod HTTP method to use when sending chunks to the server (POST, PUT, PATCH) (Default: POST)
• parameterNamespace Extra prefix added before the name of each parameter included in the multipart POST or in the test GET. (Default: '')
• headers Extra headers to include in the multipart POST with data. This can be an object or a function that allows you to construct and return a value, based on supplied file (Default: {})
• method Method to use when sending chunks to the server (multipart or octet) (Default: multipart)
• prioritizeFirstAndLastChunk Prioritize first and last chunks of all files. This can be handy if you can determine if a file is valid for your service from only the first or last chunk. For example, photo or video meta data is usually located in the first part of a file, making it easy to test support from only the first chunk. (Default: false)
• testChunks Make a GET request to the server for each chunks to see if it already exists. If implemented on the server-side, this will allow for upload resumes even after a browser crash or even a computer restart. (Default: true)
• preprocess Optional function to process each chunk before testing & sending. Function is passed the chunk as parameter, and should call the preprocessFinished method on the chunk when finished. (Default: null)
• generateUniqueIdentifier(file, event) Override the function that generates unique identifiers for each file. May return Promise-like object with then() method for asynchronous id generation. Parameters are the ES File object and the event that led to adding the file. (Default: null)
• maxFiles Indicates how many files can be uploaded in a single session. Valid values are any positive integer and undefined for no limit. (Default: undefined)
• maxFilesErrorCallback(files, errorCount) A function which displays the please upload n file(s) at a time message. (Default: displays an alert box with the message Please n one file(s) at a time.)
• minFileSize The minimum allowed file size. (Default: undefined)
• minFileSizeErrorCallback(file, errorCount) A function which displays an error a selected file is smaller than allowed. (Default: displays an alert for every bad file.)
• maxFileSize The maximum allowed file size. (Default: undefined)
• maxFileSizeErrorCallback(file, errorCount) A function which displays an error a selected file is larger than allowed. (Default: displays an alert for every bad file.)
• fileType The file types allowed to upload. An empty array allow any file type. (Default: [])
• fileTypeErrorCallback(file, errorCount) A function which displays an error a selected file has type not allowed. (Default: displays an alert for every bad file.)
• maxChunkRetries The maximum number of retries for a chunk before the upload is failed. Valid values are any positive integer and undefined for no limit. (Default: undefined)
• chunkRetryInterval The number of milliseconds to wait before retrying a chunk on a non-permanent error. Valid values are any positive integer and undefined for immediate retry. (Default: undefined)
• withCredentials Standard CORS requests do not send or set any cookies by default. In order to include cookies as part of the request, you need to set the withCredentials property to true. (Default: false)
• xhrTimeout The timeout in milliseconds for each request (Default: 0)

Server-side setup

Most of the magic happens in the user's browser, but files still need to be reassembled from chunks on the server side. This should be a fairly simple task, which and can be achieved using any web framework or language that is capable of handling file uploads.

To handle the state of upload chunks, a number of extra parameters are sent along with all requests:

• resumableChunkNumber: The index of the chunk in the current upload. First chunk is 1 (no base-0 counting here).
• resumableTotalChunks: The total number of chunks.
• resumableChunkSize: The general chunk size. Using this value and resumableTotalSize you can calculate the total number of chunks.
• resumableCurrentChunkSize: The current chunk size. Please note that this value might be lower or higher than resumableChunkSize for the last chunk of a file.
• resumableTotalSize: The total file size.
• resumableIdentifier: A unique identifier for the file contained in the request.
• resumableFilename: The original file name (since a bug in Firefox results in the file name not being transmitted in chunk multipart posts).
• resumableRelativePath: The file's relative path when selecting a directory (defaults to file name in all browsers except Chrome).

You should allow for the same chunk to be uploaded more than once; this isn't standard behaviour, but on an unstable network environment it could happen.

For every request, you can confirm reception in HTTP status codes (can be change through the permanentErrors option):

• 200: The chunk was accepted and correct. No need to re-upload.
• 400, 404, 405, 415, 501: The file for which the chunk was uploaded is not supported, cancel the entire upload.
• Anything else: Something went wrong, but try reuploading the file.