CODEWITHSUNDEEP
pythonsqlalchemyflask-sqlalchemy
axmug
axmug

Reputation: 466

Cannot define a primary key

I'm trying to define a primary key in a table using SQLAlchemy. The problem is that I can't do it due to the following error:

ArgumentError: Mapper Mapper|BankAccount|bank_account could not assemble any primary key columns for mapped table 'bank_account'

My code is this one:

from flask import Flask,request,jsonify
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
import os

# init app
app = Flask(__name__) 
basedir = os.path.abspath(os.path.dirname(__file__))

# Database
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + 
os.path.join(basedir,'db.sqlite')

app.config ['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

# init db

db = SQLAlchemy(app)
# init marshmallow
ma = Marshmallow(app)

# class account
class BankAccount(db.Model):
    number_acc: db.Column(db.String(50), primary_key = True)
    owner_acc: db.Column(db.String(50))
    bank: db.Column(db.String(50))
    amount_acc: db.Column(db.Float)

    # constructor of the class
   def __init__(self,number_acc,owner_acc,bank,amount_acc):
       self.number_acc = number_acc
       self.owner_acc = owner_acc
       self.bank = bank
       self.amount_acc = amount_acc

How can I insert the primary key in the table bank_account?

Upvotes: 2

Views: 267

Answers (1)

Ilja Everilä
Ilja Everilä

Reputation: 52929

SQLAlchemy Column objects are not type annotations, so you must assign them as class attributes instead – see "Declaring a Mapping" & "Mapping Table Columns":

class BankAccount(db.Model):
    number_acc = db.Column(db.String(50), primary_key = True)
    owner_acc = db.Column(db.String(50))
    bank = db.Column(db.String(50))
    amount_acc = db.Column(db.Float)

In your current attempt you effectively have no columns that Declarative can find during class construction, since the column information is hidden in the annotations.

Upvotes: 1

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