CODEWITHSUNDEEP
pythonflasksqlalchemyflask-sqlalchemy
Aakash Dasgupta
Aakash Dasgupta

Reputation: 74

Flask-SQLAlchemy - get distinct elements in QuerySelectField?

So I am populating the queryselectfield from my database.

def place_query():
    
    return Place.query
    
class CreateItineraryForm(FlaskForm):

   opts = QuerySelectField('Select a city',query_factory=place_query,allow_blank=True,get_label='city',validators=[DataRequired()])

   days = IntegerField('Enter the number of days of stay',validators=[DataRequired()])

   submit = SubmitField("Generate Itinerary")

But since my database has multiple tuples with the same city. So in my select field the same city shows up multiple times. Is there a way I can select only distinct city names?

This is the schema if that's helpful -

class Place(db.Model):

__tablename__ = 'places'

id = db.Column(db.Integer,primary_key=True)

name = db.Column(db.String(64),nullable=False,index=True)

lat = db.Column(db.Float,nullable=False)

long = db.Column(db.Float,nullable=False)

city = db.Column(db.String(30),nullable=False,index=True)

user_reviews = db.relationship('Review',backref='subject',lazy=True)

def __init__(self,name,lat,long,city):

self.name = name

self.lat = lat

self.long = long

self.city = city

Thanks for the help!

Upvotes: 0

Views: 172

Answers (1)

Aakash Dasgupta
Aakash Dasgupta

Reputation: 74

So the trick was to not use QuerySelectField but to use SelectField.

This is the new code -

# this returns a tuple of the form (city_name,)
cities = db.session.query(Place.city).group_by(Place.city).order_by(Place.city).all()

city_list = []

# here we create a list from the tuple
def create_list(cities):
    for city in cities:
        city_list.append(city[0])

    return city_list

And the new select field looks like this -

opts = SelectField('Select a city',validators=[DataRequired()],choices=create_list(cities))

Upvotes: 1

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