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Python

Andy Hughes
Andy Hughes
8,479 Points
Posted by Andy Hughes
Andy Hughes
8,479 Points

How to modify this for updating things

I keep writing this and ending up with pages, so I'll bullet point it to be concise :)

1) Trying to create an update function for the social app. 2) Can't get it to update the database with the new information. Info just stays the same. 3) Tried .save() and .update() but neither makes a difference.

I'm building on what Kenneth developed so it's Sqlite, Flask, Peewee.

What am I trying to achieve? 1) I have a view that shows a database table. Each row has a 'delete' and 'update' link. 2) Clicking 'update' uses the ID from the row to take the user to a form that should allow them to update that row. 3) The form seems to work ok and I get no errors, but the database functionality is not updating the row and that's what I want it to do.

I need some help :) Relevant code is below.

app.py

'''updates a standard'''
@app.route('/update_standard/<int:id>', methods=('GET', 'POST'))
@login_required
def update_standard(id):
    form = forms.UpdateForm()
    if form.validate_on_submit():
        models.Standards.change_standard(
            section=form.section.data,
            standard=form.standard.data)
        flash("Standard updated! Thanks!", "success")
        return redirect(url_for('view_standards'))
    return render_template('update-standard.html', form=form, id=id)

models.py

class Standards(Model):
    section = CharField(unique=False)
    standard = CharField(unique=True)

    class Meta:
        database = DATABASE


    @classmethod
    def create_standard(cls, section, standard):
        try:
            with DATABASE.transaction():
                cls.create(
                    section=section,
                    standard=standard
                )
        except IntegrityError:
            raise ValueError("Section or Standard already exists")


    @classmethod
    def delete_standard(cls, id, section, standard):
        try:
            with DATABASE.transaction():
                cls.delete(
                    id=id,
                    section=section,
                    standard=standard)
        except IntegrityError:
            raise ValueError("Standard does not exist for deletion")


    @classmethod
    def change_standard(cls, section, standard):
        try:
            with DATABASE.transaction():
                cls.update(
                    section=section,
                    standard=standard)
        except IntegrityError:
            raise ValueError("Standard does not exist for update")

forms.py

class UpdateForm(FlaskForm):
    section = TextAreaField('Enter new section', validators=[DataRequired(), section_exists])
    standard = TextAreaField('Enter new standard', validators=[DataRequired(), standard_exists])

1 Answer

jb30
jb30
44,806 Points

In models.py, try changing change_standard to

    @classmethod
    def change_standard(cls, id, section, standard):
        try:
            with DATABASE.transaction():
                standards_to_update = cls.get_by_id(id) # specifies which Standards to update
                standards_to_update.section = section # updates the value for section
                standards_to_update.standard = standard # updates the value for standard
                standards_to_update.save() # saves changes
        except DoesNotExist:
            raise ValueError("Standard does not exist for update")

and passing in id as an argument for models.Standards.change_standard in app.py

        models.Standards.change_standard(
            id=id,
            section=form.section.data,
            standard=form.standard.data)
Andy Hughes
Andy Hughes
8,479 Points
Andy Hughes
Andy Hughes
8,479 Points

jb30 - Sir, you are a bloomin superstar! Thank you. It works perfectly.

Just let me work through the logic to see if I understand what you're answer is doing. :)

1) change_standard is receiving the ID, Section, Standard from my form view? 2) you then look for the passed in record with the 'get_by_id(id)'? 3) you then relate 'section' and 'standard' to the 'standards_to_update' variable that already knows the record from the ID? 4) You then use the save() to update the database?

It's just important for me to understand how it works in case I need to do it again. :)

Thank you again for the support.

jb30
jb30
44,806 Points

1) change_standard is receiving the section and standard from the form, and the id from def update_standard(id):

2) Yes. There are ways to find which record it is from the section or standard, but you might be changing those values in change_standard and the section and standard are not guaranteed to be unique.

3) Yes.

4) Yes.