Dynamic choices WTForms Flask SelectField

问题

I\'m trying to pass userID variable to WTForms with FlaskForms. First I\'ll show code that works fine and then what I need to modify(that the part I don\'t know how). I\'m adding new Name associated with some group.

FlaskForm model:

class AddName(FlaskForm):
    name =StringField(\'Device name\', validators=[InputRequired(),Length(min=4, max=30)])
    groupID = SelectField(\'Payload Type\', choices=[(1,\"Group1\"),(2,\"Group2\")], validators=[InputRequired])

View model:

@app.route(\'/dashboard/addname\', methods=[\'GET\', \'POST\'])
def addname():
    form=AddName()
    if form.validate_on_submit():
        name=Name(form.name.data,form.groupID.data)
        db.session.add(name)
        db.session.commit()
        return \"New name added\"

Template:

              <form method=\"POST\" action=\"/dashboard/addname\">
                  <h2>Add name</h2>
                  {{ form.hidden_tag() }}
                  {{ wtf.form_field(form.name) }}
                  {{ wtf.form_field(form.groupID) }}
                  <button type=\"submit\">Add name</button>
              </form>

I see correct list in dropdown, and on submit gives me correct numbers.

Task: I need to pass different list based on current_user.userID. I\'m forming list using SQLAlchemy, by making query from table from DB, so My Flask view is:

@app.route(\'/dashboard/addname\', methods=[\'GET\', \'POST\'])
def addname():
    available_groups=db.session.query(Groups).filter(Groups.userID == currend_user.userID).all()
    #Now forming the list of tuples, so it\'s ok for SelectField
    groups_list=[(i.groupID, i.groupName) for i in available_groups]
    form=AddName()
    if form.validate_on_submit():
        name=Name(form.name.data,form.groupID.data)
        db.session.add(name)
        db.session.commit()
        return \"New name added\"

1. How can i pass my groups_list to the form? I tried to implement forming procedure in the FlaskForm model, but it doesn\'t see current_user object
2. Do I need to transform groupID to string and then back to int when I need to pass it to the SelectField like tuples?

回答1:

The main idea here is to assign the choices list to the field after instantiation. To do so you need to use argument coerce=int. The coerce keyword arg to SelectField says that we use int() to coerce form data. The default coerce is unicode().

Correct FormModel:

class AddName(FlaskForm):
    name =StringField('Device name', validators=[InputRequired(),Length(min=4, max=30)])
    groupID = SelectField('Payload Type', coerce=int, validators=[InputRequired])

Correct View:

@app.route('/dashboard/addname', methods=['GET', 'POST'])
def addname():
    available_groups=db.session.query(Groups).filter(Groups.userID == currend_user.userID).all()
    #Now forming the list of tuples for SelectField
    groups_list=[(i.groupID, i.groupName) for i in available_groups]
    form=AddName()
    #passing group_list to the form
    form.groupID.choices = groups_list
    if form.validate_on_submit():
        name=Name(form.name.data,form.groupID.data)
        db.session.add(name)
        db.session.commit()
        return "New name added"

来源：https://stackoverflow.com/questions/46921823/dynamic-choices-wtforms-flask-selectfield