How to get SelectField current value with Flask WTF

问题

I making a gender form using Flask-WTF, here is the snippet of my code:

class Gender(enum.Enum):
    Male = 'Male'
    Female = 'Female'

    def __str__(self):
        return self.value

gender = [(str(y), y) for y in (Gender)]

class EditStudentForm(Form):
    gender = SelectField('Gender', choices=gender)

@app.route('/edit_student')
def edit_student():
    student = Student.query.filter_by(id=student_id).first()
    student_form = EditStudentForm()
    # ... validate on submit
        # ....
        # ....
    return render_template(student=student, student_form=student_form)

That code already works, included I can insert the data to the database.

But, if the current user gender value on database is Female, whenever I refresh the browsers, the form did not get the current value.

In HTML I want it to be like this:

// edit form
<form>
  <input type="" value="currentUserValueFromDatabase">
</form>

I try to get current value using this way:

{{ f.render_field(student_form.gender, value=student.gender) }}

But it didn't prepopulate the current value from current user gender.

So what I want is to to display current value on selectfield or prepopulate the selectfield according to the current user value on the database.

回答1:

Pass student to the EditStudentForm as the obj keyword argument, e.g.:

student_form = EditStudentForm(obj=student_form)

Why? From WTForms docs:

obj – If formdata is empty or not provided, this object is checked for attributes matching form field names, which will be used for field values.

When you construct the form when handling a GET request, there is no form data, so it will use the object data.

回答2:

I think what you need is to set default value of gender field before you pass the form object to template. Try below.

@app.route('/edit_student')
def edit_student():
    student = Student.query.filter_by(id=student_id).first()
    student_form = EditStudentForm()
    # set default
    student_form.gender.default = student.gender
    # process it to propagate the change.
    student_form.process() 
    # ... validate on submit
        # ....
        # ....
    return render_template(student_form=student_form)

来源：https://stackoverflow.com/questions/57830463/how-to-get-selectfield-current-value-with-flask-wtf

标签

Flask

flask-wtforms

wtforms