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July 27, 2021 08:14
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Minimal example of not working cascaded deleting
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| from flask import Flask | |
| from flask_migrate import Migrate | |
| from flask_sqlalchemy import SQLAlchemy | |
| app = Flask(__name__) | |
| app.config["SQLALCHEMY_DATABASE_URI"] = f"sqlite:///testing.sqlite3" | |
| app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False | |
| db = SQLAlchemy(app) | |
| db.session().execute("PRAGMA foreign_keys=ON") | |
| migrate = Migrate(app, db) | |
| import models | |
| import routes | |
| # this is just for testing purposes. uncomment to get a clean DB after each server restart | |
| # db.drop_all() | |
| # db.create_all() |
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| <!-- should be placed under templates/ --> | |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>{{msg}}</title> | |
| </head> | |
| <body> | |
| <p>{{msg}}</p> | |
| <form method="post" action="/project"> | |
| <input type="submit" value="Create"> | |
| <input type="submit" formaction="/delete" value="Delete"> | |
| </form> | |
| <h1>Projects</h1> | |
| {% for project in projects %} | |
| <p>{{ project }}</p> | |
| {% endfor %} | |
| <h1>Labels</h1> | |
| {% for label in labels %} | |
| <p>{{ label }}</p> | |
| {% endfor %} | |
| <h1>Files</h1> | |
| {% for file in files %} | |
| <p>{{ file }}</p> | |
| {% endfor %} | |
| <h1>Results</h1> | |
| {% for result in results %} | |
| <p>{{ result }}</p> | |
| {% endfor %} | |
| </body> | |
| </html> |
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| from app import app | |
| from app import db | |
| from datetime import datetime | |
| from sqlalchemy_serializer import SerializerMixin | |
| class BaseModel(db.Model, SerializerMixin): | |
| __abstract__ = True | |
| serialize_only = ("id", "name",) | |
| date_format = '%s' # Unixtimestamp (seconds) | |
| datetime_format = '%d. %b. %Y %H:%M:%S' | |
| time_format = '%H:%M' | |
| id = db.Column(db.Integer, primary_key=True) | |
| name = db.Column(db.String, nullable=False) | |
| def __repr__(self): | |
| attrs = self.to_dict() | |
| content = ", ".join([f"{attr}={value}" for attr, value in attrs.items()]) | |
| return f"<{self.__class__.__name__}: {content}>" | |
| def delete(self, commit=True) -> None: | |
| db.session.delete(self) | |
| if commit: | |
| self.commit() | |
| @classmethod | |
| def new(cls, commit=True, **kwargs): | |
| obj = cls(**kwargs) | |
| db.session.add(obj) | |
| if commit: | |
| obj.commit() | |
| return obj | |
| def commit(self): | |
| db.session.commit() | |
| db.session.commit() | |
| class Project(BaseModel): | |
| serialize_only = BaseModel.serialize_only + ("created",) | |
| root_folder = db.Column(db.String) | |
| created = db.Column(db.DateTime, default=datetime.utcnow, | |
| index=True, nullable=False) | |
| # contraints | |
| __table_args__ = () | |
| files = db.relationship("File", | |
| backref="project", | |
| passive_deletes=True) | |
| labels = db.relationship("Label", | |
| backref="project", | |
| passive_deletes=True) | |
| class Label(BaseModel): | |
| serialize_only = BaseModel.serialize_only + \ | |
| ("created", "reference", "project_id") | |
| project_id = db.Column( | |
| db.Integer, | |
| db.ForeignKey("project.id", ondelete="CASCADE"), | |
| nullable=False) | |
| created = db.Column(db.DateTime, default=datetime.utcnow, | |
| index=True, nullable=False) | |
| reference = db.Column(db.String) | |
| __table_args__ = ( | |
| db.UniqueConstraint('project_id', 'reference'), | |
| ) | |
| class File(BaseModel): | |
| serialize_only = BaseModel.serialize_only + \ | |
| ("path", "project_id") | |
| project_id = db.Column( | |
| db.Integer, | |
| db.ForeignKey("project.id", ondelete="CASCADE"), | |
| nullable=False) | |
| path = db.Column(db.String, nullable=False) | |
| results = db.relationship("Result", backref="file", passive_deletes=True) | |
| class Result(BaseModel): | |
| serialize_only = BaseModel.serialize_only + \ | |
| ("file_id", "label_id") | |
| file_id = db.Column( | |
| db.Integer, | |
| db.ForeignKey("file.id", ondelete="CASCADE"), | |
| nullable=False) | |
| label_id = db.Column( | |
| db.Integer, | |
| db.ForeignKey("label.id", ondelete="SET NULL"), | |
| nullable=True) | |
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| flask | |
| flask-sqlalchemy | |
| flask-migrate | |
| SQLAlchemy-serializer |
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| import random | |
| from app import app | |
| from flask import render_template | |
| from flask import redirect | |
| from models import * | |
| @app.route("/") | |
| def index(): | |
| projects = Project.query.all() | |
| labels = Label.query.all() | |
| files = File.query.all() | |
| results = Result.query.all() | |
| return render_template("index.html", | |
| msg="Index", | |
| projects=projects, | |
| labels=labels, | |
| files=files, | |
| results=results, | |
| ) | |
| @app.route("/project", methods=["POST"]) | |
| def new_project(): | |
| project = Project.new(name="Project", root_folder="some_folder") | |
| for n in range(random.randint(1, 10)): | |
| Label.new(name="A label", project_id=project.id, reference=f"Label #{n+1:04d}") | |
| for n in range(random.randint(1, 4)): | |
| file = File.new(name="A file", project_id=project.id, path=f"some_file_{n:04d}.txt") | |
| for n in range(random.randint(1, 3)): | |
| label = random.choice(Label.query.filter_by(project_id=project.id).all()) | |
| Result.new(name="A result", file_id=file.id, label_id=label.id) | |
| return redirect("/") | |
| @app.route("/delete", methods=["POST"]) | |
| def del_project(): | |
| project = Project.query.first() | |
| if project is not None: | |
| project.delete(commit=True) | |
| return redirect("/") | |
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