How to return form field errors to template rendered in a different django view - django

Question

I have a django bootstrap 4 template (wordcloud.html) that contains a form. The form was originally created as raw html within wordcloud.html, and the view for that template populates the fields. The form (create_wordcloud_form) uses post to send the data to a different view (create_wordcloud_view.py). The original developer didn't use django's built in template/form/view structure, so there is no form.py nor a form template.
The issue I need to address is validating the form. It has to be server-side validation, as one of the fields needs to be tested against one of the databases to prevent duplicate fields.
Do I need to refactor the whole mess into the standard django template/form/view idiom using crispy-forms, or is there a way to use what I already have and return some error messages from the view that processes the form data?
The code for validating the fields is easy. I am not sure how to structure the return statement in the event there are field errors, since wordcloud.html is rendered in a different view.
create_wordcloud_view:
#method_decorator(login_required, name='post')
class CreateWordCloud(View):
def post(self, request):
logger.debug("CreateWordCloud START")
q_dict = request.POST
logger.debug("q_dict=%s" % q_dict)
sources = []
filters = {}
cloud_name = None
for key in q_dict:
logger.debug("key=%s" % key)
if key == 'csrfmiddlewaretoken':
continue
if key in ["Titles", "Descriptions", "Comments", "Translations", "Text"]:
sources.append(key)
elif key == 'wordcloud_name':
cloud_name = q_dict['wordcloud_name']
else:
values = q_dict.getlist(key)
if len(values) == 1:
filters[key] = values[0]
else:
filters[key] = values
# Need to add field validation here
# 1. Must have at least one source
# 2. wordcloud_name must not be in the table of wordclouds
# 3. Alert user that no words were found for the combination of sources
# and filters selected
from wordcloud.tasks import create_wordcloud_task_3
create_wordcloud_task_3(None, cloud_name, sources, filters=filters)
# If the form data is valid and more than a few words are returned from
# create_wordcloud_task_3, then redirect to wordcloud.html
return redirect("/memorabilia/wordcloud.html", permanent=False)
# If form is invalid or no words returned from create_wordcloud_task_3,
# return to wordcloud.html with original data and appropriate field error
# messages.
return ????
create_wordcloud_form (a snippet from the wordcloud.html template):
<div id="wordcloud_form" style="display: none;">
<form action="/wordcloud/ajax/create_wordcloud/" class="was-validated" method="post">{% csrf_token %}
<div class="form-row">
<div class="col-md-12">
<p>First, select the source of words:</p>
</div>
</div>
<div class="form-row">
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="source_text" name="Text">
<label class="form-check-label" for="source_text">Text</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="source_translation" name="Translations">
<label class="form-check-label" for="source_translation">Translations</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="source_titles" name="Titles">
<label class="form-check-label" for="source_titles">Titles</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="source_descriptions" name="Descriptions">
<label class="form-check-label" for="source_descriptions">Descriptions</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="source_comments" name="Comments">
<label class="form-check-label" for="source_comments">Comments</label>
</div>
<span>{{ form_sources_required }}
</div>
<div class="form-row mt-3">
<div class="col-md-12">
<p>Second, filter documents based on the metadata, if desired:</p>
</div>
</div>
{% for category in categories %}
{% if forloop.counter0|divisibleby:3 %}
<div class="form-row">
{% endif %}
<div class="col">
<label>{{ category.label }}</label>
<select class="selectpicker" name="{{ category.label }}" multiple data-size="10">
{% for option in category.options %}
<option>{{ option }}</option>
{% endfor %}
</select>
</div>
{% if forloop.counter|divisibleby:3 %}
</div>
{% endif%}
{% endfor %}
<div class="form-row mt-3">
<div class="col-md-12">
<div class="form-group">
<label for="wordcloud_name">Finally, give your wordcloud a name</label>
<input type="text" name="wordcloud_name" class="form-control" id="wordcloud_name" placeholder="Enter your wordcloud name">
<div class="invalid-feedback">{{ form_cloud_name_required }} {{ form_duplicate_cloud_name_error }}</div>
</div>
</div>
</div>
<div class="form-row mt-3">
<div class="col-md-12">
<button type="submit" class="btn btn-primary">Submit</button>
</div>
</div>
</form>
</div>
A picture of the rendered form:

Answer 1

You can create a django form with the same field names as your html form.
After you submit the form you can check if it valid:
form = YourForm(request.POST)
# check whether it's valid:
if form.is_valid():
...
Then if the form is not valid you can show the errors in your template like so:
<div class="form-group">
<label for="wordcloud_name">Finally, give your wordcloud a name</label>
<input type="text" name="wordcloud_name" class="form-control" id="wordcloud_name" placeholder="Enter your wordcloud name">
<div class="invalid-feedback">{{ form.wordcloud_name.errors }}</div>
</div>