CODEWITHSUNDEEP
pythonsqlalchemyflask-sqlalchemy
Charlie Brown
Charlie Brown

Reputation: 469

Cannot test simple sqlalchemy model dataclass: "Mapper mapped class could not assemble any primary key columns for mapped table"

I have a simple Python script (models.py) to create a Flask-SQLAlchemy app and a simple sqlalchemy dataclass (reference here) that looks like this:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = "sqlite:///test.db"
db = SQLAlchemy(app)

class User(db.Model):

    __tablename__ = 'user'

    user_id: db.Column(db.Integer, primary_key=True)
    user_url: db.Column(db.String(2083), unique=True, nullable=False)
    username: db.Column(db.String(80), unique=True, nullable=False)
    avatar_url: db.Column(db.String(2083), unique=True, nullable=False)

I then wrote an extremely simple pytest script that looks like this, following the example on creating a Flask-SQLAlchemy app from here:

import pytest

from models import User
from models import db

def test_basic():

    db.create_all()

    u1 = User(1, "http://testuserurl", "charliebrown", "http://avatarurl")

    assert u1.user_id == 1
    assert u1.user_url == "http://testuserurl"
    assert u1.username == "charliebrown"
    assert u1.avatar_url == "http://avatarurl"

This test fails immediately on the line "from models import User" with the message:

sqlalchemy.exc.ArgumentError: Mapper mapped class User->user could not assemble any primary key columns for mapped table 'user'

I don't understand this message (specially given that I do indeed specify the primary_key in User). Any help please?

Upvotes: 0

Views: 3579

Answers (1)

Hemi03
Hemi03

Reputation: 34

Try to use = instead of :

Like this:

class User(db.Model):

    __tablename__ = 'user'

    user_id = db.Column(db.Integer, primary_key=True)
    user_url = db.Column(db.String(2083), unique=True, nullable=False)
    username = db.Column(db.String(80), unique=True, nullable=False)
    avatar_url = db.Column(db.String(2083), unique=True, nullable=False)

Upvotes: 2

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