1+ import 'dart:collection' ;
2+ import 'dart:convert' ;
13import 'dart:io' ;
24
5+ import 'package:http_parser/http_parser.dart' ;
6+ import 'package:mime/mime.dart' ;
7+
38/// Content-Type: application/x-www-form-urlencoded
49final formUrlEncodedContentType = ContentType (
510 'application' ,
611 'x-www-form-urlencoded' ,
712);
813
9- /// Parses the body as form data and returns a `Future<Map<String, String>>` .
10- /// Throws a [StateError] if the MIME type is not "application/x-www-form-urlencoded"
14+ /// Content-Type: multipart/form-data
15+ final multipartFormDataContentType = ContentType (
16+ 'multipart' ,
17+ 'form-data' ,
18+ );
19+
20+ /// Parses the body as form data and returns a `Future<Map<String, dynamic>>` .
21+ /// Throws a [StateError] if the MIME type is not "application/x-www-form-urlencoded" or "multipart/form-data".
1122/// https://fetch.spec.whatwg.org/#ref-for-dom-body-formdata%E2%91%A0
12- Future <Map < String , String > > parseFormData ({
23+ Future <FormData > parseFormData ({
1324 required Map <String , String > headers,
1425 required Future <String > Function () body,
26+ required Stream <List <int >> Function () bytes,
1527}) async {
1628 final contentType = _extractContentType (headers);
17- if (! _isFormUrlEncoded (contentType)) {
29+ final isFormUrlEncoded = _isFormUrlEncoded (contentType);
30+ final isMultipartFormData = _isMultipartFormData (contentType);
31+
32+ if (! isFormUrlEncoded && ! isMultipartFormData) {
1833 throw StateError (
1934 '''
2035Body could not be parsed as form data due to an invalid MIME type.
21- Expected MIME type: "${formUrlEncodedContentType .mimeType }"
36+ Expected MIME type: "${formUrlEncodedContentType .mimeType }" OR "${ multipartFormDataContentType . mimeType }"
2237Actual MIME type: "${contentType ?.mimeType ?? '' }"
2338''' ,
2439 );
2540 }
2641
27- return Uri .splitQueryString (await body ());
42+ return isFormUrlEncoded
43+ ? _extractFormUrlEncodedFormData (body: await body ())
44+ : await _extractMultipartFormData (headers: headers, bytes: bytes ());
2845}
2946
3047ContentType ? _extractContentType (Map <String , String > headers) {
@@ -37,3 +54,145 @@ bool _isFormUrlEncoded(ContentType? contentType) {
3754 if (contentType == null ) return false ;
3855 return contentType.mimeType == formUrlEncodedContentType.mimeType;
3956}
57+
58+ bool _isMultipartFormData (ContentType ? contentType) {
59+ if (contentType == null ) return false ;
60+ return contentType.mimeType == multipartFormDataContentType.mimeType;
61+ }
62+
63+ FormData _extractFormUrlEncodedFormData ({required String body}) {
64+ return FormData (fields: Uri .splitQueryString (body), files: {});
65+ }
66+
67+ final _keyValueRegexp = RegExp ('(?:(?<key>[a-zA-Z0-9-_]+)="(?<value>.*?)";*)+' );
68+
69+ Future <FormData > _extractMultipartFormData ({
70+ required Map <String , String > headers,
71+ required Stream <List <int >> bytes,
72+ }) async {
73+ final contentType = headers[HttpHeaders .contentTypeHeader]! ;
74+ final mediaType = MediaType .parse (contentType);
75+ final boundary = mediaType.parameters['boundary' ];
76+ final transformer = MimeMultipartTransformer (boundary! );
77+
78+ final fields = < String , String > {};
79+ final files = < String , UploadedFile > {};
80+
81+ await for (final part in transformer.bind (bytes)) {
82+ final contentDisposition = part.headers['content-disposition' ];
83+ if (contentDisposition == null ) continue ;
84+ if (! contentDisposition.startsWith ('form-data;' )) continue ;
85+
86+ final values = _keyValueRegexp
87+ .allMatches (contentDisposition)
88+ .fold (< String , String > {}, (map, match) {
89+ return map..[match.namedGroup ('key' )! ] = match.namedGroup ('value' )! ;
90+ });
91+
92+ final name = values['name' ]! ;
93+ final fileName = values['filename' ];
94+
95+ if (fileName != null ) {
96+ files[name] = UploadedFile (
97+ fileName,
98+ ContentType .parse (part.headers['content-type' ] ?? 'text/plain' ),
99+ part,
100+ );
101+ } else {
102+ final bytes = (await part.toList ()).fold (< int > [], (p, e) => p..addAll (e));
103+ fields[name] = utf8.decode (bytes);
104+ }
105+ }
106+
107+ return FormData (fields: fields, files: files);
108+ }
109+
110+ /// {@template form_data}
111+ /// The fields and files of received form data request.
112+ /// {@endtemplate}
113+ class FormData with MapMixin <String , String > {
114+ /// {@macro form_data}
115+ const FormData ({
116+ required Map <String , String > fields,
117+ required Map <String , UploadedFile > files,
118+ }) : _fields = fields,
119+ _files = files;
120+
121+ final Map <String , String > _fields;
122+
123+ final Map <String , UploadedFile > _files;
124+
125+ /// The fields that were submitted in the form.
126+ Map <String , String > get fields => Map .unmodifiable (_fields);
127+
128+ /// The files that were uploaded in the form.
129+ Map <String , UploadedFile > get files => Map .unmodifiable (_files);
130+
131+ @override
132+ @Deprecated ('Use `fields[key]` to retrieve values' )
133+ String ? operator [](Object ? key) => _fields[key] ?? _files[key]? .toString ();
134+
135+ @override
136+ @Deprecated ('Use `fields.keys` to retrieve field keys' )
137+ Iterable <String > get keys => _fields.keys;
138+
139+ @override
140+ @Deprecated ('Use `fields.values` to retrieve field values' )
141+ Iterable <String > get values => _fields.values;
142+
143+ @override
144+ @Deprecated (
145+ 'FormData should be immutable, in the future this will thrown an error' ,
146+ )
147+ void operator []= (String key, String value) => _fields[key] = value;
148+
149+ @override
150+ @Deprecated (
151+ 'FormData should be immutable, in the future this will thrown an error' ,
152+ )
153+ void clear () => _fields.clear ();
154+
155+ @override
156+ @Deprecated (
157+ 'FormData should be immutable, in the future this will thrown an error' ,
158+ )
159+ String ? remove (Object ? key) => _fields.remove (key);
160+ }
161+
162+ /// {@template uploaded_file}
163+ /// The uploaded file of a form data request.
164+ /// {@endtemplate}
165+ class UploadedFile {
166+ /// {@macro uploaded_file}
167+ const UploadedFile (
168+ this .name,
169+ this .contentType,
170+ this ._byteStream,
171+ );
172+
173+ /// The name of the uploaded file.
174+ final String name;
175+
176+ /// The type of the uploaded file.
177+ final ContentType contentType;
178+
179+ final Stream <List <int >> _byteStream;
180+
181+ /// Read the content of the file as a list of bytes.
182+ ///
183+ /// Can only be called once.
184+ Future <List <int >> readAsBytes () async {
185+ return (await _byteStream.toList ())
186+ .fold <List <int >>([], (p, e) => p..addAll (e));
187+ }
188+
189+ /// Open the content of the file as a stream of bytes.
190+ ///
191+ /// Can only be called once.
192+ Stream <List <int >> openRead () => _byteStream;
193+
194+ @override
195+ String toString () {
196+ return '{ name: $name , contentType: $contentType }' ;
197+ }
198+ }
0 commit comments