Flask 图像字段，如何在更新 wtform 中填充图像字段？

Question

I have an app where user can add, update and delete virtual assistants. To update them I have used populate_obj method. It takes all fields from original virtual assistant like name, last_name and populates fields in update form, but it does not populate image field. Because of that user has to upload photo even if he does not want to update this row. For example: user wants to update only name, he pushes the button update, writes new name, and pushes the button submitt, then he get information "choose photo", but he does not need to write new last_name it is populated and I want the same with photo. I am wondering what can be solution here? I mean how can I populate photo row so user does not have to choose photo each time?

Model

class VirtualAssistant(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(30))
    last_name = db.Column(db.String(30))
    image_filename = db.Column(db.String)
    image_url = db.Column(db.String)

View:

@app.route("/update/<int:id>/", methods=["GET", "POST"])
def update_virtual_assistant(id):
    updated_virtual_assistant = VirtualAssistant.query.get_or_404(id)
    form = UpdateVirtualAssistant(obj=updated_virtual_assistant)
    if request.method == "POST":
        if form.validate_on_submit():
            form.populate_obj(updated_virtual_assistant)
            if "photo" in request.files:
                photo = request.files["photo"]
                filename = photos.save(form.photo.data)
                url = photos.url(filename)
                path = "C:\\Users\\Luiza\\VirtualAssistants\\static\\img\\" + filename
                resize_photo(path)
                updated_virtual_assistant.image_url = url
                updated_virtual_assistant.image_filename = filename
            db.session.commit()
            return "the virtual assistant has been updated"
    return render_template("UpdateVirtualAssistant.html", updated_virtual_assistant=updated_virtual_assistant, form=form)

forms:

class AddVirtualAssistant(FlaskForm):
    name = StringField("name", validators=[DataRequired()])
    last_name = StringField("last_name", validators=[DataRequired()])
    photo = FileField("photo", validators=[DataRequired()])

class UpdateVirtualAssistant(AddVirtualAssistant):
    id = IntegerField("id", validators=[DataRequired()])

HTML:

<form method="POST" enctype="multipart/form-data">
    {{ form.csrf_token }}
    {{ form.id }}</br>
    {{ form.name }}</br></br>
    {{ form.last_name }}</br></br>
    {{ form.photo }}</br></br>
    <button type="submit">Update assistant</button>
</form>

Answer 1

You should make a separate class for UpdateVirtualAssistant() instead. This way the photo does not have the DataRequired() validator and you wouldn't have to worry about the "choose photo" validator flag in the first place. Also consider using the FileAllowed() validator to only allow certain file types.

class UpdateVirtualAssistant(FlaskForm):
    id = IntegerField("id", validators=[DataRequired()])
    name = StringField("name", validators=[DataRequired()])
    last_name = StringField("last_name", validators=[DataRequired()])
    photo = FileField("photo", validators=[FileAllowed(['jpg','jpeg','png'])])