SelectField option to dynamically populate default value in TextAreaField using WTForms - flask

Question

I have a SelectField that is populated from a database table. I load the choices into the form as follows:
#statuses.route('/new', methods=['GET', 'POST'])
#login_required
def new_status():
form = StatusForm()
form.status_cd.choices = [(a.id, a.status_cd) for a in \
Status_Code.query.order_by('status_cd')]
if form.validate_on_submit():
status = Status(author=current_user)
form.to_model(status)
db.session.add(status)
db.session.commit()
flash('The status was added successfully.')
return redirect(url_for('.index'))
return render_template('statuses/new_status.html', form=form)
The model referenced in the query is as follows:
class Status_Code(db.Model):
__tablename__ = 'status_cd'
id = db.Column(db.Integer, primary_key=True)
status_cd = db.Column(db.String(16), nullable=False)
status_detail = db.Column(db.Text)
is_option_active = db.Boolean()
date_created = db.Column(db.DateTime, default=db.func.now())
And the form class is as follows:
class StatusForm(Form):
datetime = DateTimeField('Date / Time')
name = StringField('Name', validators=[Required()])
status_cd = SelectField('Status Code', coerce=int)
status_detail = TextAreaField('Status Detail', default="Default text",\
validators=[Required()])
submit = SubmitField('Submit')
The Question
Depending on the option selected in the SelectField, I want it to dynamically set the status_detail TextAreaField's default text. The value from the SelectField should query the database and return the status_detail, which should be the default text.
For example, if I have:
id status_cd status_detail
1 Apple The apples are red.
2 Banana The bananas are yellow.
If the user selects the "Apple" option, the default text should be "The apples are red."
Any assistance would be greatly appreciated! I am building my first Flask app so I'm new to this.

Answer 1

In my experience with flask, you can do this a couple of ways. There is no right way, and it is all up to you:
You can load the status_detail data, and place it in a data-detail tag in your select option value:
<select name='status_cd' onchange="get_status(this);">
{% for s in status %}
<option value='{{ s.id }}' data-detail='{{ s.status_detail }}'>{{ s.status_cd }} </option>
{% endfor %}
</select>
Then you can do an onchange with JavaScript, which can then get the data-detail value and update your text box (this is pseudo code, not meant for copy and paste):
<script>
function onchange(o){
var value = $(o).attr('data-detail');
//do something with the value
}
</script>
OR
You can do it where it pulls from the database dynamically if you don't wan to put the data-detail tag in your code, like this:
Same onchange with JavaScript, but can then do a call to an Ajax call to your routed method to return your value (this is pseudo code, not meant for copy and paste):
<script>
function onchange(o){
var value = $(o).value();
$.ajax({
url: '/my_rout',
data: value,
success : function(data){
//handle your result here
}
})
}
</script>
I hope this at least gets you in the right direction with some different options to choose from.