misc: allow prefilling file fields with a dictionary (#25385)

tests/form_pages/test_file_field.py

@@ -526,6 +526,38 @@ def test_form_file_field_dict_prefill(pub):
     assert formdata.data['0'].get_content() == b'hello\n'
 
 
+@responses.activate
+def test_form_file_field_url_prefill(pub):
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'test'
+    formdef.fields = [
+        fields.FileField(
+            id='0',
+            label='file',
+            prefill={'type': 'string', 'value': 'http://example.net/hello.txt'},
+        )
+    ]
+    formdef.store()
+
+    responses.get('http://example.net/hello.txt', body=b'Hello\n', content_type='text/plain')
+    resp = get_app(pub).get('/test/')
+    assert resp.form['f0$token'].value
+    assert resp.click('hello.txt').content_type == 'text/plain'
+    resp = resp.form.submit('submit')  # -> validation
+    resp = resp.form.submit('submit')  # -> submit
+    formdata = formdef.data_class().select()[0]
+    assert formdata.data['0'].base_filename == 'hello.txt'
+    assert formdata.data['0'].get_content() == b'Hello\n'
+
+    pub.loggederror_class.wipe()
+    responses.get('http://example.net/hello.txt', status=404)
+    resp = get_app(pub).get('/test/')
+    assert not resp.form['f0$token'].value
+    assert 'hello.txt' not in resp.text
+    assert [x.summary for x in pub.loggederror_class.select()] == ['Failed to convert value for field "file"']
+
+
 SVG_CONTENT = b'''<?xml version="1.0" encoding="utf-8"?>
 <svg version="1.1" id="Calque_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
 viewBox="0 0 63.72 64.25" style="enable-background:new 0 0 63.72 64.25;" xml:space="preserve"> <g> </g> </svg>'''

wcs/fields/file.py

@@ -16,6 +16,7 @@
 
 import base64
 import os
+import urllib.parse
 import xml.etree.ElementTree as ET
 
 from django.utils.encoding import force_bytes, force_str
@@ -139,6 +140,20 @@ class FileField(WidgetField):
             upload = PicklableUpload(value.filename, value.content_type)
             upload.receive([value.content])
             return upload
+
+        value = misc.unlazy(value)
+        if isinstance(value, str) and urllib.parse.urlparse(value).scheme in ('http', 'https'):
+            try:
+                response, status, data, dummy = misc.http_get_page(value, raise_on_http_errors=True)
+            except misc.ConnectionError:
+                pass
+            else:
+                value = {
+                    'filename': os.path.basename(urllib.parse.urlparse(value).path) or _('file.bin'),
+                    'content': data,
+                    'content_type': response.headers.get('content-type'),
+                }
+
         if isinstance(value, dict):
             # if value is a dictionary we expect it to have a content or
             # b64_content key and a filename keys and an optional

wcs/qommon/form.py

@@ -924,13 +924,20 @@ class FileWithPreviewWidget(CompositeWidget):
         return False
 
     def set_value(self, value):
-        if isinstance(value, dict):
+        if isinstance(value, (str, dict)):
             from wcs.fields.file import FileField
 
             try:
                 value = FileField.convert_value_from_anything(value)
-            except ValueError:
+            except ValueError as e:
                 value = None
+                if getattr(self, 'field', None):
+                    get_publisher().record_error(
+                        _('Failed to convert value for field "%s"') % self.field.label,
+                        formdef=getattr(self, 'formdef', None),
+                        exception=e,
+                    )
+
         try:
             self.value = value
             if self.value and self.get_value_from_token: