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

• application/x-www-form-urlencoded
• application/json
• multipart/form-data

Parsing the body

All you need to do to parse a request body is call RequestContext.parseBody. This methodis idempotent, and only ever performs the body-parsing logic once, so it is recommended to callit 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:

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

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

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

11. // To access the body, regardless of its runtime type:
12. var objectBody = req.bodyAsObject as SomeType;
13. });

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, andaccessing the contents of an uploaded file as a Stream<List<int>>:

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

4. var file = req.uploadedFiles.first;

6. if (file.contentType.type == 'video') {
7. // Write directly to a file.
8. await file.data.pipe(someFile.openWrite());
9. }
10. });

Custom Body Parsing

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

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

8. for (var file in archive.files) {
9. fields[file.path] = file.mode;
10. }

12. req.bodyAsMap = fields;
13. }

15. return true;
16. });
17. }

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