Update existing Posts in "Build a social Network with Flask". Has anyone built this functionality?

Question

How would I proceed if I wanted to make this possible? Do I make it as a function on the class or in app.py?

Currently I'm thinking of making it in the app.py. But honestly, I have no idea.. I've found this in the docs but I'm not sure how I could use it.

@app.route('/edit/<int:post_id>', methods=('GET', 'POST'))
@login_required
def edit_post(post_id)
    edit = models.Post.select().where(models.Post.id == post_id)
    form = forms.PostForm()

How do I populate the existing form in post.html with the data?

Answer 1 · 2016-06-04T11:51:36Z

June 4, 2016 11:51am

@app.route('/edit_post/<int:post_id>', methods=('GET', 'POST'))
@login_required
def edit_post(post_id):
    form = forms.PostForm()
    if form.validate_on_submit():
        new_content = form.content.data.strip()
        q = models.Post.update(content=new_content).where(models.Post.id == Post_id)
        q.execute()
        flash("Post updated", "success")
        return redirect(url_for('index'))
    return render_template('edit_post.html', form=form)

Figured out the update part. Just missing the part where the form i filled out with the old content when the editing is opened.

UPDATE June 5. 2345: Did it. In case anyone needs this:

@app.route('/edit_post/<int:post_id>', methods=('GET', 'POST'))
@login_required
def edit_post(post_id):
    edit = models.Post.select().where(models.Post.id == post_id).get()
    form = forms.PostForm(obj=edit)
    form.populate_obj(edit)
    if form.validate_on_submit():
        new_content = form.content.data.strip()
        new_finished = form.finished.data
        q = models.Post.update(content=new_content, finished=new_finished).where(models.Post.id == post_id)
        q.execute()
        flash("Post updated", "success")
        return redirect(url_for('index'))
    return render_template('edit_post.html', form=form)

Credits to: (flask-wtf-tricks)[https://goonan.io/flask-wtf-tricks/]

Answer 2 · 2016-06-14T06:46:03Z

June 14, 2016 6:46am

Thanks for sharing, Michael! Super helpful.

I found this line especially neat! form = forms.PostForm(obj=edit)

And it saves a ton of time trying to pre-populate this over and over again for however many fields you have: form.<field>.data = edit.<field>

I am, however, a bit lost as to what the form.populate_obj(edit) line does.

I did a bit of digging in the wtforms library.

def populate_obj(self,obj):
python
for name, field in iteritems(self._fields):
            field.populate_obj(obj, name)

I don't really understand what self._fields means, but I assume it's referencing the /fields/core.py as that's the only other place I could find populate_obj. We see in /fields/core.py:

    def populate_obj(self, obj, name):
        """
        Populates `obj.<name>` with the field's data.
        :note: This is a destructive operation. If `obj.<name>` already exists,
               it will be overridden. Use with caution.
        """
        setattr(obj, name, self.data)

So populate_obj iterates over each record (field) in a row (model instance) and calls setattr. But why do we need to call this before we get data out of our form?

I'm able to have users edit their records without this line. Is there any reason to keep it? What does it do?

https://github.com/wtforms/wtforms/blob/master/wtforms/form.py https://github.com/wtforms/wtforms/blob/master/wtforms/fields/core.py

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Michael Kristiansen

Michael Kristiansen

Update existing Posts in "Build a social Network with Flask". Has anyone built this functionality?

2 Answers

Michael Kristiansen

Michael Kristiansen

Denton Zhou

Denton Zhou