我已将MultiCheckboxField添加到我的Flask应用(as per the docs)，但是当我在其上使用validate_on_submit方法时，此字段无法验证，因为它似乎没有choices属性，即使我已明确设置它。
class MultiCheckboxField(SelectMultipleField):
"""
A multiple-select, except displays a list of checkboxes.
Iterating the field will produce subfields, allowing custom rendering of
the enclosed checkbox fields.
"""
widget = ListWidget(prefix_label=False)
option_widget = CheckboxInput()
class DocumentProcessForm(Form):
"""
Allows the user to select which documents should be processed.
"""
PROCESS = "0"
DELETE = "-1"
files = MultiCheckboxField("Select", coerce=int)
#Custom fields I made that render <button>s:
process_button = ButtonField("Process", name="action", value=PROCESS)
delete_button = ButtonField("Delete", name="action", value=DELETE)
@app.route(app.config["PROJECT_ROUTE"] + "<project_id>",
methods=["GET", "POST"])
def project_show(project_id):
"""
Show the files contained in a specific project. It also allows the user
to upload a new document, much like projects().
:param int project_id: The ID of the desired project.
"""
process_form = forms.DocumentProcessForm(prefix="process")
if process_form.validate_on_submit(): #This fails
files = request.form.getlist("process-files")
if len(files) > 0:
if request.form["action"] == process_form.DELETE:
delete(files)
elif request.form["action"] == process_form.PROCESS:
#TODO: process these files.
pass
# The template needs access to the ID of each file and its filename.
process_form.files.choices = []
file_objects = GetFiles(project_id) # database query, this works fine
for file_object in file_objects:
process_form.files.choices.append((file_object.id,
os.path.split(file_object.path)[1]))
return render_template("document_list.html",
process_form=process_form,
allowed_extensions=app.config["ALLOWED_EXTENSIONS"])
在我的模板中：
<form method="POST" role="form">
{{ process_form.hidden_tag() }}
<table>
<thead>
<tr>
<th>Filename</th>
<th>Select</th>
</tr>
</thead>
<tbody>
{% for file in process_form.files %}
<tr>
<td>
<label for="{{ file.id }}">
<a href="{{ url_for('document_show',
document_id=file.data,
project_id=project.id) }}">{{ file.label.text }}</a>
</label>
</td>
<td>
{{ file }}
</td>
</tr>
{% endfor %}
</tbody>
</table>
<h3>Selected file actions:</h3>
{{ process_form.process_button(class="btn btn-primary") }}
{{ process_form.delete_button(class="btn btn-danger") }}
</form>
Flask返回错误：
Traceback (most recent call last):
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/home/plasmasheep/prog/project/app/views.py", line 84, in project_show
if really_submitted(process_form):
File "/home/plasmasheep/prog/project/app/views.py", line 22, in really_submitted
return form.validate_on_submit() and form.submitted.data
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/flask_wtf/form.py", line 156, in validate_on_submit
return self.is_submitted() and self.validate()
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/wtforms/form.py", line 271, in validate
return super(Form, self).validate(extra)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/wtforms/form.py", line 130, in validate
if not field.validate(self, extra):
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/wtforms/fields/core.py", line 164, in validate
self.pre_validate(form)
File "/home/plasmasheep/prog/project/venv/lib/python2.7/site-packages/wtforms/fields/core.py", line 465, in pre_validate
values = list(c[0] for c in self.choices)
TypeError: 'NoneType' object is not iterable
self.choices为None。但是，self.data确实包含所选的复选框。我不知道该怎么做。
答案 0 :(得分：0)
这一行
files = MultiCheckboxField("Select", coerce=int)
应改为：
my_choices = [('0', 'PROCESS'), ('-1', 'DELETE')]
files = MultiCheckboxField("Select", choices = my_choices, coerce=int)
您需要提供＆＃34;选择＆＃34;实例化文件字段时的属性。
答案 1 :(得分：0)
问题是我在运行choices后添加到validate_on_submit。如果我像这样重新排列project_show：
@app.route(app.config["PROJECT_ROUTE"] + "<project_id>",
methods=["GET", "POST"])
def project_show(project_id):
"""
Show the files contained in a specific project. It also allows the user
to upload a new document, much like projects().
:param int project_id: The ID of the desired project.
"""
process_form = forms.DocumentProcessForm(prefix="process")
# The template needs access to the ID of each file and its filename.
# Note where this has been moved!
process_form.files.choices = []
file_objects = GetFiles(project_id) # database query, this works fine
for file_object in file_objects:
process_form.files.choices.append((file_object.id,
os.path.split(file_object.path)[1]))
if process_form.validate_on_submit(): #This works fine
files = request.form.getlist("process-files")
if len(files) > 0:
if request.form["action"] == process_form.DELETE:
delete(files)
elif request.form["action"] == process_form.PROCESS:
#TODO: process these files.
pass
return render_template("document_list.html",
process_form=process_form,
allowed_extensions=app.config["ALLOWED_EXTENSIONS"])