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Parsing Request Bodies
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 the following content types:
application/x-www-form-urlencodedapplication/jsonmultipart/form-data
Parsing the body
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:1
app.post('/my_form', (req, res) async {
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// Parse the body, if it has not already been parsed.
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await req.parseBody();
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​
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// Access fields from the body, which is the most common use case.
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var userId = req.bodyAsMap['user_id'] as String;
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​
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// If the user posted a List, i.e., through JSON:
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var count = req.bodyAsList.length;
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​
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// To access the body, regardless of its runtime type:
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var objectBody = req.bodyAsObject as SomeType;
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});
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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>>:1
app.post('/upload', (req, res) async {
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await req.parseBody();
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​
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var file = req.uploadedFiles.first;
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​
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if (file.contentType.type == 'video') {
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// Write directly to a file.
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await file.data.pipe(someFile.openWrite());
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}
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});
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Custom Body Parsing
You can handle other content types by manually parsing the body. You can set
bodyAsObject, bodyAsMap, or bodyAsList exactly once:1
Future<void> unzipPlugin(Angel app) async {
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app.fallback((req, res) async {
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if (!req.hasParsedBody
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&& req.contentType.mimeType == 'application/zip') {
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var archive = await decodeZip(req.body);
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var fields = <String, dynamic>{};
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​
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for (var file in archive.files) {
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fields[file.path] = file.mode;
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}
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​
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req.bodyAsMap = fields;
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}
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​
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return true;
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});
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}
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If the user did not provide a
content-type header when parseBody is called, a 400 Bad Request error will be thrown.Last modified 3yr ago
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