Angel3 Developer Guide
  • README
  • Foreword
  • Tutorial
    • Getting Started
    • Minimal Setup
  • Command Line Interface
    • Setup
  • Templates and Views
    • Server Side Rendered Views
    • JAEL3
      • About
      • Basics
      • Custom Elements
      • Strict Resolution
      • Directive: declare
      • Directive: for-each
      • Directive: extend
      • Directive: if
      • Directive: include
      • Directive: switch
  • Authentication
    • About
    • Strategies
    • Local
  • Databases
    • Object Relational Mapping (ORM)
      • About
      • Basic Functionality
      • Relations
      • Migrations
      • PostgreSQL
    • NoSQL
  • Extensions and Plugins
    • Using Plug-ins
    • Writing a Plugin
  • Under the hood
    • Basic Routing
    • Requests & Responses
    • Request Lifecycle
    • Dependency Injection
    • Middleware
    • Controllers
    • Parsing Request Bodies
    • Serialization
    • Service Basics
    • Testing
    • Error Handling
    • Pattern Matching and Parameter
  • Angel Framework Migration
    • Angel 2.x.x to Angel3
      • Rationale - Why a new Version?
      • Framework Changelog
      • 3.0.0 Migration Guide
    • Angel 1.x.x to 2.x.x
      • Framework Changelog
      • 2.0.0 Migration Guide
  • Packages
    • Authentication
    • CORS
    • Database-Agnostic Relations
    • Configuration
    • Databases
      • ORM
      • MongoDB
      • JSON File-based
      • RethinkDB
    • Templates and Views
      • Jael template engine
      • Mustache Templates
      • compiled_mustache-based engine
      • html_builder-based engine
      • Markdown template engine
      • Using Angel with Angular
    • Hot Reloading
    • Pagination
    • Polling
    • Production Utilities
    • REST Client
    • Reverse Proxy
    • Router
    • Serialization
    • Service Seeder
    • Static Files
    • Security
    • Server-sent Events
    • shelf Integration
    • Task Engine
    • User Agents
    • Validation
    • Websockets
  • Resources
    • Dependency Injection Patterns
    • Example Projects
    • YouTube Tutorials
    • Ecosystem
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On this page
  • Body Parsing
  • Handling File Uploads
  • Custom Body Parsing

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  1. Under the hood

Parsing Request Bodies

Interactive Web applications typically require some type of user input (whether that user is a human, machine, or otherwise is irrelevant). Angel3 features built-in support for parsing request bodies with the following content types:

  • application/x-www-form-urlencoded

  • application/json

  • multipart/form-data

Body Parsing

All you need to do to parse a request body is call RequestContext.parseBody. This method is idempotent, and only ever performs the body-parsing logic once, so it is recommended to call it any time you access the request body, unless you are 100% sure that it has been parsed before.

You can access the body as a Map, List, or Object, depending on your use case:

app.post('/my_form', (req, res) async {
    // Parse the body, if it has not already been parsed.
    await req.parseBody();

    // Access fields from the body, which is the most common use case.
    var userId = req.bodyAsMap['user_id'] as String;

    // If the user posted a List, i.e., through JSON:
    var count = req.bodyAsList.length;

    // To access the body, regardless of its runtime type:
    var objectBody = req.bodyAsObject as SomeType;
});

Handling File Uploads

In the case of multipart/form-data, Angel will also populate the uploadedFiles field. The UploadedFile wrapper class provides mechanisms for reading content types, metadata, and accessing the contents of an uploaded file as a Stream<List<int>>:

app.post('/upload', (req, res) async {
    await req.parseBody();

    var file = req.uploadedFiles.first;

    if (file.contentType.type == 'video') {
        // Write directly to a file.
        await file.data.pipe(someFile.openWrite());
    }
});

Custom Body Parsing

You can handle other content types by manually parsing the body. You can set bodyAsObject, bodyAsMap, or bodyAsList exactly once:

Future<void> unzipPlugin(Angel app) async {
    app.fallback((req, res) async {
        if (!req.hasParsedBody
            && req.contentType.mimeType == 'application/zip') {
            var archive = await decodeZip(req.body);
            var fields = <String, dynamic>{};

            for (var file in archive.files) {
                fields[file.path] = file.mode;
            }

            req.bodyAsMap = fields;
        }

        return true;
    });
}

If the user did not provide a content-type header when parseBody is called, a 400 Bad Request error will be thrown.

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Last updated 3 years ago

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