ListField is showing <ul> instead of <input> in edit/create post - flask

Question

I am using Flask, mongoengine for a project and I am trying to get basic stuff working from http://docs.mongodb.org/manual/tutorial/write-a-tumblelog-application-with-flask-mongoengine/
After implementing everything from above link I added a new field for "tags" in Post and when I try to create a post, my tags doesn't show a input box.
Any help is appreciated.
My code and screenshot below
class Post(db.DynamicDocument):
created_at = db.DateTimeField(default=datetime.datetime.now, required=True)
title = db.StringField(max_length=255, required=True)
slug = db.StringField(max_length=255, required=True)
comments = db.ListField(db.EmbeddedDocumentField('Comment'))
tags = db.ListField(db.StringField(max_length=30)) # New field I added
template form
{% macro render(form) -%}
<fieldset>
{% for field in form %}
{% if field.type in ['CSRFTokenField', 'HiddenField'] %}
{{ field() }}
{% else %}
<div class="clearfix {% if field.errors %}error{% endif %}">
{{ field.label }}
<div class="input">
{% if field.name == "body" %}
{{ field(rows=10, cols=40) }}
{% else %}
{{ field() }}
{% endif %}
{% if field.errors or field.help_text %}
<span class="help-inline">
{% if field.errors %}
{{ field.errors|join(' ') }}
{% else %}
{{ field.help_text }}
{% endif %}
</span>
{% endif %}
</div>
</div>
{% endif %}
{% endfor %}
</fieldset>
{% endmacro %}
rendering form code
{% extends "admin/base.html" %}
{% import "_forms.html" as forms %}
{% block content %}
<h2>
{% if create %}
Add new Post
{% else %}
Edit Post
{% endif %}
</h2>
<form action="?{{ request.query_string }}" method="post">
{{ forms.render(form) }}
<div class="actions">
<input type="submit" class="btn primary" value="save">
Cancel
</div>
</form>
{% endblock %}

Answer 1

From what I can gather, your problem is you're telling WTF to render the tags field, but WTForms doesn't know how to handle that information.
From looking at the Flask-MongoEngine documentation, it seems the ListField is just a FieldList as WTForms refers to it.
Currently you're not actually defining the form independently in WTForms, you're just using the magic included in Flask-MongoEngine, so my first attempt would be to add some more logic to your macro, add a {% elif field.type == 'ListField' %} and try and discover what's contained in there to iterate through to produce your form. From having a quick look at the source-code, something like the following might work.
{% elif field.type == 'ListField %}
{# render_the_group_label #}
{% for subfield in field.entries %}
{% if subfield.type == 'StringField' %}
{# render_the_subfield #}
{% endif %}
{% endfor %}
...
That code will need to be worked on, but hopefully it'll point you in the right direction. Otherwise, I'd actually define the form seperately in WTForms to give you a bit more control on the code-side. Luckily they provide a csv tag example which should help you if you need to go that route. I wrote a guide that takes a different route using #property decorators to achieve a similar effect, which again, might at least point you towards the finish line.