Flask WTF 'StringField' object has no attribute 'translate'
<p>I am relatively new to Python, and I've been following the <a href="http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world" rel="noreferrer">Miguel Grinberg Flask Mega-Tutorial</a>.</p>

<p>I have a very simple form which, when I try to submit, I receive the following error:</p>

<blockquote>
  <p>AttributeError: 'StringField' object has no attribute 'translate'</p>
</blockquote>

<p>Here is the form:</p>

<pre><code>from flask.ext.wtf import Form
from wtforms import StringField
from wtforms.validators import DataRequired


class CreateSubjectForm(Form):
    name = StringField('name', validators=[DataRequired()])
</code></pre>

<p>And <code>views.py</code>:</p>

<pre><code>@app.route('/create_subject', methods=['GET', 'POST'])
def create_subject():
    form = CreateSubjectForm()
    if form.validate_on_submit():
        subject = Subject(name=form.name)
        db.session.add(subject)
        db.session.commit()
    return render_template('create_subject.html',
                           title='Create Subject',
                           form=form)
</code></pre>

<p>My template is as follows:</p>

<pre><code>{% extends "base.html" %}

{% block content %}
    &lt;h2&gt;Create Subject&lt;/h2&gt;
    &lt;form action="" method="post" name="create_subject"&gt;
        {{ form.hidden_tag() }}
        &lt;div class="form-control-label"&gt;Name: &lt;/div&gt;
        &lt;div class="form-control"&gt;{{ form.name(size=45) }}&lt;/div&gt;
        &lt;input type="submit" value="Create"&gt;
    &lt;/form&gt;
{% endblock %}
</code></pre>

<p>I have been unable to solve this problem, but here is what I have looked at.</p>

<p>One concern arose from the fact that PyCharm tells me that it cannot find <code>wtf</code> in <code>flask.ext</code> in the line <code>from flask.ext.wtf import Form</code>.  I am using Python 2.7.  From research it appears that this is the correct way to import for 2.7.  I tried changing it to <code>from flask_wtf import Form</code> and the PyCharm error goes away, but the behaviour is the same.</p>

<p>From the traceback I thought it looked like something has gone wrong with versions and packages.  I double check I had everything installed with <code>pip.install</code> and it appears I do - here is <code>pip.freeze</code> from the virtual environment:</p>

<pre><code>Babel==2.2.0
blinker==1.4
coverage==4.0.3
decorator==4.0.9
Flask==0.10.1
Flask-Babel==0.9
Flask-Login==0.3.2
Flask-Mail==0.9.1
Flask-OpenID==1.2.5
Flask-SQLAlchemy==2.1
Flask-WhooshAlchemy==0.56
Flask-WTF==0.12
flipflop==1.0
guess-language==0.2
itsdangerous==0.24
Jinja2==2.8
MarkupSafe==0.23
pbr==1.8.1
PyMySQL==0.7.2
python-openid==2.2.5
pytz==2016.3
six==1.10.0
speaklater==1.3
SQLAlchemy==1.0.12
sqlalchemy-migrate==0.10.0
sqlparse==0.1.19
Tempita==0.5.2
Werkzeug==0.11.5
Whoosh==2.7.3
WTForms==2.1
</code></pre>

<p>And here is the traceback:</p>

<pre><code>&gt; Traceback (most recent call last):   File
&gt; "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1836, in __call__
&gt;     return self.wsgi_app(environ, start_response)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1820, in wsgi_app
&gt;     response = self.make_response(self.handle_exception(e))   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1403, in handle_exception
&gt;     reraise(exc_type, exc_value, tb)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1817, in wsgi_app
&gt;     response = self.full_dispatch_request()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1477, in full_dispatch_request
&gt;     rv = self.handle_user_exception(e)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1381, in handle_user_exception
&gt;     reraise(exc_type, exc_value, tb)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1475, in full_dispatch_request
&gt;     rv = self.dispatch_request()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\flask\app.py",
&gt; line 1461, in dispatch_request
&gt;     return self.view_functions[rule.endpoint](**req.view_args)   File "C:\Users\timni\onedrive\dev\studyplanner\app\views.py", line 24, in
&gt; create_subject
&gt;     db.session.commit()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\scoping.py",
&gt; line 157, in do
&gt;     return getattr(self.registry(), name)(*args, **kwargs)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 801, in commit
&gt;     self.transaction.commit()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 392, in commit
&gt;     self._prepare_impl()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 372, in _prepare_impl
&gt;     self.session.flush()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 2019, in flush
&gt;     self._flush(objects)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 2137, in _flush
&gt;     transaction.rollback(_capture_exception=True)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\util\langhelpers.py",
&gt; line 60, in __exit__
&gt;     compat.reraise(exc_type, exc_value, exc_tb)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\session.py",
&gt; line 2101, in _flush
&gt;     flush_context.execute()   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\unitofwork.py",
&gt; line 373, in execute
&gt;     rec.execute(self)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\unitofwork.py",
&gt; line 532, in execute
&gt;     uow   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\persistence.py",
&gt; line 174, in save_obj
&gt;     mapper, table, insert)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\orm\persistence.py",
&gt; line 800, in _emit_insert_statements
&gt;     execute(statement, params)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\base.py",
&gt; line 914, in execute
&gt;     return meth(self, multiparams, params)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\sql\elements.py",
&gt; line 323, in _execute_on_connection
&gt;     return connection._execute_clauseelement(self, multiparams, params)   File
&gt; "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\base.py",
&gt; line 1010, in _execute_clauseelement
&gt;     compiled_sql, distilled_params   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\base.py",
&gt; line 1146, in _execute_context
&gt;     context)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\base.py",
&gt; line 1344, in _handle_dbapi_exception
&gt;     util.reraise(*exc_info)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\base.py",
&gt; line 1139, in _execute_context
&gt;     context)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\sqlalchemy\engine\default.py",
&gt; line 450, in do_execute
&gt;     cursor.execute(statement, parameters)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\cursors.py",
&gt; line 156, in execute
&gt;     query = self.mogrify(query, args)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\cursors.py",
&gt; line 135, in mogrify
&gt;     query = query % self._escape_args(args, conn)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\cursors.py",
&gt; line 115, in _escape_args
&gt;     return dict((key, conn.escape(val)) for (key, val) in args.items())   File
&gt; "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\cursors.py",
&gt; line 115, in &lt;genexpr&gt;
&gt;     return dict((key, conn.escape(val)) for (key, val) in args.items())   File
&gt; "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\connections.py",
&gt; line 781, in escape
&gt;     return escape_item(obj, self.charset, mapping=mapping)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\converters.py",
&gt; line 26, in escape_item
&gt;     val = encoder(val, mapping)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\converters.py",
&gt; line 109, in escape_unicode
&gt;     return u"'%s'" % _escape_unicode(value)   File "C:\Users\timni\onedrive\dev\studyplanner\venv\lib\site-packages\pymysql\converters.py",
&gt; line 72, in _escape_unicode
&gt;     return value.translate(_escape_table) AttributeError: 'StringField' object has no attribute 'translate'
</code></pre>

<p>So at this point I am stumped.  Any help will be very greatly appreciated.  Thank you.</p>