How do I pre-fill a Flask WTForms Form with existing data for an "Edit Profile" route?-CodePudding

The problem

Whenever I write data to the attribute form.[any-field-name].data, the written data appears in the form, which is what I want. However, if a change is made in the form field when the form is rendered, the new value seems to only be stored in form.[any-field-name].raw_data. form.[any-field-name].data merely shows the original value that was written to .data before the user had the chance to type a new value in the field.

Obviously I could just grab the results from .raw_data, but that would defeat the purpose of having a form validation library. How can I elegantly pre-fill form fields for the user while allowing Flask-WTForms to accept fresh data from those same fields?

FYI: This is a bit different from a typical "edit profile" route, as my app creates a new UserVersion record every time a profile edit is made.

The Flask route

@app.route("/edit_user", methods=["GET", "POST"])
@login_required
def edit_user_self():
    """Edit user account that is currently logged in."""

    # get latest version of currently logged in user
    user_version = current_user.user_versions[0]

    # instantiate form and fill with existing data
    form = EditUserForm()
    form.username.data = user_version.username
    form.email.data = user_version.email
    form.addr_housenumber.data = user_version.addr_housenumber
    form.addr_street.data = user_version.addr_street
    form.addr_unit.data = user_version.addr_unit
    form.addr_city.data = user_version.addr_city
    form.addr_state.data = user_version.addr_state
    form.addr_postcode.data = user_version.addr_postcode

    if not form.validate_on_submit():
        return render_template("edit_user.html", form=form)
    else:
        # create new user version
        new_user_version = UserVersion(user=current_user,
            username = form.username.data,
            password = user_version.password,
            email = form.email.data,
            addr_housenumber = form.addr_housenumber.data,
            addr_street = form.addr_street.data,
            addr_unit = form.addr_unit.data,
            addr_city = form.addr_city.data,
            addr_state = form.addr_state.data,
            addr_postcode = form.addr_postcode.data
        )

        db.session.add(new_user_version)
        db.session.commit()

        flash("Changes saved")
        return redirect("/view_user")

The form model

class EditUserForm(FlaskForm):
    username = StringField(
        "Username", validators=[DataRequired(message="Please enter a username")]
    )
    email = StringField(
        "Email",
        validators=[
            DataRequired(),
            Email(message="Please enter a valid email address"),
        ],
    )
    addr_housenumber = StringField("Housenumber", validators=[Length(max=80)])
    addr_housename = StringField("Housename", validators=[Length(max=80)])
    addr_conscriptionnumber = StringField(
        "Conscription Number", validators=[Length(max=80)]
    )
    addr_street = StringField("Street", validators=[Length(max=80)])
    addr_place = StringField("Place", validators=[Length(max=80)])
    addr_postcode = StringField("Postcode", validators=[Length(max=80)])
    addr_city = StringField("City", validators=[Length(max=80)])
    addr_country = StringField("Country", validators=[Length(max=80)])
    addr_hamlet = StringField("Hamlet", validators=[Length(max=80)])
    addr_suburb = StringField("Suburb", validators=[Length(max=80)])
    addr_subdistrict = StringField("Subdistrict", validators=[Length(max=80)])
    addr_province = StringField("Province", validators=[Length(max=80)])
    addr_state = StringField("State", validators=[Length(max=80)])
    addr_door = StringField("Door", validators=[Length(max=80)])
    addr_unit = StringField("Unit", validators=[Length(max=80)])
    addr_floor = StringField("Floor", validators=[Length(max=80)])
    addr_block = StringField("Block", validators=[Length(max=80)])
    submit = SubmitField("Save")

Library versions

Flask 1.1.2
Flask WTForms 0.14.3
Flask SQLAlchemy 2.1

CodePudding user response：

I use placeholder for this purpose. You can pre-fill in the edit_user_self by mean of:

form.username.render_kw({'placeholder':user_version.email})

Oterwise you can do it in jinja like this:

{{wtf.form_field(form.email,
 placeholder=user_version.email)}}

but to do so you should pass additional information to jinja template.

CodePudding user response：

You need to swap your logic around. Test for form submission and validate first, else pre-populate and return the form:

@app.route('/submit', methods=['GET', 'POST'])
def submit():
    form = MyForm()
    
    if form.validate_on_submit():
        #Validate and Process submitted form first:
        new_user_version = UserVersion(user=current_user,
                                       username = form.username.data)

        db.session.add(new_user_version)
        db.session.commit()
        return redirect('/success')

    user_version = current_user.user_versions[0]
    #Pre-populate your form here:
    form.username.data = user_version.username

    return render_template('submit.html', form=form)