In django forms custom widget return list as value instead of string

Question

Hi I am writting a custom widget which I want to return a list as the value. From what I can find to set the value that is returned you create a custom value_from_datadict function. I have done this

def value_from_datadict(self, data, files, name):
    value = data.get(name, None)
    if value:
        # split the sting up so that we have a list of nodes
        tag_list = value.strip(',').split(',')
        retVal = []
        # loop through nodes
        for node in tag_list:
            # node string should be in the form: node_id-uuid
            strVal = str(node).split("-")

            uuid = strVal[-1]
            node_id = strVal[0]

            # create a tuple of node_id and uuid for node
            retVal.append({'id': node_id, 'uuid': uuid})

        if retVal:
            # if retVal is not empty. i.e. we have a list of nodes
            # return this. if it is empty then just return whatever is in data
            return retVal

    return value

I expect this to return a list but when I print out the value it is returned as a string rather than a list. The string itself contains the right text but as i said it is a string and not a list. An example of what is returned could be

[{'id': '1625', 'uuid': None}]

but if I did str[0] it would print out [ instead of {'id': '1625', 'uuid': None}

How can I stop it from converting my list into a string?

Thanks

Answer 1

Well, it's simple: if you have a CharField, then you will get a string as a result, because CharField uses method to_python, that coerces the result to string. You need to create your own Field for this one and return a list.

OLD

Could you post the result of:

x = value_from_datadict(..)
print type(x)

so we can see, what exactly is returned?

And could you post the whole test case you are using to deliver the example?

Answer 2

widget.py

class AutoTagWidget(widgets.TextInput):
  def render(self, name, value, attrs=None):
    final_attrs = self.build_attrs(attrs, name=name)

    if not self.attrs.has_key('id'):
        final_attrs['id'] = 'id_%s' % name

    jquery = u"""
    <script type="text/javascript">
    $("#%s").tokenInput('%s', {
        hintText: "Enter the topic you wish to tag this resource to",
        noResultsText: "No results",
        prePopulate: %s,
        searchingText: "Searching..."
    });

    $("body").focus();
    </script>
    """ % (final_attrs['id'], reverse('ajax_autocomplete'), value)

    output = super(AutoTagWidget, self).render(name, "", attrs)

    return output + mark_safe(jquery)

  def value_from_datadict(self, data, files, name):
    #return data.get(name, None)
    value = data.get(name, None)
    if value:
        # split the sting up so that we have a list of nodes
        tag_list = value.strip(',').split(',')
        retVal = []
        # loop through nodes
        for node in tag_list:
            # node string should be in the form: node_id-uuid
            strVal = str(node).split("-")

            uuid = strVal[-1]
            node_id = strVal[0]

            # create a tuple of node_id and uuid for node
            retVal.append({'id': node_id, 'uuid': uuid})

        if retVal:
            # if retVal is not empty. i.e. we have a list of nodes
            # return this. if it is empty then just return whatever is in data
            return retVal

    return value

forms.py

class TagResourceForm(forms.Form):
     Tag_Resource_To = forms.CharField(max_length=255, widget=AutoTagWidget,required=False)

view.py

def tag_resource(request, slug):
  if request.method == 'POST':
    form = TagResourceForm(data=request.POST)
    if form.is_valid():
        tag_list = form.cleaned_data['Tag_Resource_To']
  else:
    form = TagResourceForm()

when posting the form tag_list = [{'id': '1625', 'uuid': None}]

but it is a string not a list.

if I do eval(tag_list) then I get it as a list but I'd rather it was just a list and not a string when it is returned