API: Allow to set product pictures

src/pretix/api/serializers/fields.py

@@ -27,3 +27,50 @@ class ListMultipleChoiceField(serializers.MultipleChoiceField):
         ]
 
         return remove_duplicates_from_list(representation_data)
+
+
+class UploadedFileField(serializers.Field):
+    default_error_messages = {
+        'required': 'No file was submitted.',
+        'not_found': 'The submitted file ID was not found.',
+        'invalid_type': 'The submitted file has a file type that is not allowed in this field.',
+        'size': 'The submitted file is too large to be used in this field.',
+    }
+
+    def __init__(self, *args, **kwargs):
+        self.allowed_types = kwargs.pop('allowed_types', None)
+        self.max_size = kwargs.pop('max_size', None)
+        super().__init__(*args, **kwargs)
+
+    def to_internal_value(self, data):
+        from pretix.base.models import CachedFile
+
+        request = self.context.get('request', None)
+        try:
+            cf = CachedFile.objects.get(
+                session_key=f'api-upload-{str(type(request.user or request.auth))}-{(request.user or request.auth).pk}',
+                file__isnull=False,
+                pk=data[len("file:"):],
+            )
+        except CachedFile.DoesNotExist:
+            self.fail('not_found')
+
+        if self.allowed_types and cf.type not in self.allowed_types:
+            self.fail('invalid_type')
+        if self.max_size and cf.file.size > self.max_size:
+            self.fail('size')
+
+        return cf.file
+
+    def to_representation(self, value):
+        if not value:
+            return None
+
+        try:
+            url = value.url
+        except AttributeError:
+            return None
+        request = self.context.get('request', None)
+        if request is not None:
+            return request.build_absolute_uri(url)
+        return url