Flask-WTF selectfield with UUID

Question

I am using sqlalchemy and use UUID for the primary keys in my database (postgres)

Here is my class:

class EntityType(db.Model):
    __tablename__ = 'entity_type'

    id = db.Column(UUID(as_uuid=True), primary_key=True, server_default=db.text('gen_random_uuid()'))
    name = db.Column(db.Text, nullable=False)

In the form to add an entity, the user has to choose an entity type, I have the following

class EntityAddForm(FlaskForm):

    url = StringField('URL', validators=[DataRequired(),URL(require_tld=True)])
    entity_type = SelectField('Entity type')
    description = TextAreaField('Description')
    submit = SubmitField('Add')

    def validate_entity_type(self, entity_type):
        entity_type = EntityType.query.filter_by(id=entity_type.data).first()
        if entity_type is None:
            raise ValidationError('Please select a different entity type.')

To load the form, I have the following code to populate the selectField with rows of the table.

    form = EntityAddForm()
    form.entity_type.choices = [(et.id, et.name) for et in EntityType.query.order_by('name')]

The issue is that the if form.validate_on_submit(): does not return True on the submit.

It seems that WTForms needs a string/unicode/int using coerce for the id of the selectField

Is there a way to keep using the UUID type instead of switching to integer to get the selectField working?

I tried with QuerySelectEntity or a custom UUID type but could not succeed.

Thank you

Attack68 Attack68 · Accepted Answer · 2019-12-24T17:59:06

Have you tried either converting your database to string so that it play nice with the web:

def default_uuid():
    return uuid.uuid4().hex

class EntityType(db.Model):
    __tablename__ = 'entity_type'
    id = db.Column(db.String, primary_key=True, default=default_uuid)

or

expressly converting the data when passed to the web for use within the form:

form.entity_type.choices = [(str(et.id), et.name) for et in EntityType.query.order_by('name')]

and

def validate_entity_type(self, entity_type):
        entity_type = EntityType.query.filter_by(id=uuid.UUID(entity_type.data)).first()
        if entity_type is None:
            raise ValidationError('Please select a different entity type.')

Flask-WTF selectfield with UUID

1 Answers