init structure of backend

.env.example

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+FLASK_APP=main.py
+FLASK_ENV=development

.gitignore

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+*__pycache__
+.idea
+venv
+env
+.env
+db.sqlite
+.pytest_cache

Readme_backend.md

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+## Installation 
+Python 3.8 version is required.
+```bash
+python3 --version
+```
+
+Create virtual environment and install packages
+```bash
+virtualenv venv
+source ./venv/bin/activate
+pip install -r requirements.txt
+```
+***
+
+## Usage
+Create `.env` file  and fill with similar data like `.env.example`.
+Then run application:
+```bash
+flask run
+```
+***
+
+## Testing
+Run tests
+```bash
+pytest
+```
+***
+
+### Useful commands:
+Add new package
+```bash
+pip install NAME_OF_PACKAGE
+```
+Save new added package to requirements
+```bash
+pip freeze > requirements.txt
+```
+***
+
+#### Flask commands: 
+Create the application structure directories
+```bash
+flask startapp NAME_OF_APP
+```
+Above command create package structure:
+\
+Create serializer in `__schemas__.py` file:
+```python3 
+class ExampleSchema(ma.SQLAlchemyAutoSchema):
+    class Meta:
+        model = MODEL_NAME
+```
+\
+Create models in `__models__.py` file:
+```python3 
+class Example(db.Model):
+    __tablename__ = "examples"
+
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+    title = db.Column(db.String(255), unique=True)
+```
+\
+Create api routes in ```__routes__.py``` file. You only have to register blueprint in `app/__init__.py`.
+```python3 
+from flask import Blueprint, make_response, jsonify, Response
+
+
+bp = Blueprint("{name}", __name__, url_prefix="/{name}")
+
+
+@bp.route("/", methods=["GET"])
+def index() -> Response:
+    return make_response(jsonify({{"hello": "{name}"}}), 200)
+
+```
+\
+Print all your routes
+```bash
+flask routes
+```
+Create migration, but first you have to create model
+```bash
+flask db migrate
+```
+Apply your changes to database, use after migration command
+```bash
+flask db upgrade
+```
+If you want back changes in your databases, use below command
+```bash
+flask db downgrade
+```
+Create empty migration, you can write manually migration here. 
+```bash
+flask db revision
+```

app/__init__.py

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+import os
+
+from flask import Flask
+from flask_migrate import Migrate
+
+from .config import config
+from .dependencies import db, ma
+from .commands.startapp import startapp
+from .utils import import_models
+
+
+def create_app(config_name: str = None) -> Flask:
+    if config_name is None:
+        config_name = os.environ.get("FLASK_ENV")
+
+    app = Flask(__name__)
+    app.config.from_object(config.get(config_name) or config.get("development"))
+
+    db.init_app(app)
+    ma.init_app(app)
+
+    if config_name != "production":
+        with app.app_context():
+            import_models()
+
+    Migrate(app, db)
+
+    # register blueprints
+    # app.register_blueprint(blueprint)
+
+    # register commands
+    app.cli.add_command(startapp)
+
+    return app

app/commands/startapp.py

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+import os
+import re
+
+from flask import current_app
+from click import command, argument
+from click.exceptions import ClickException
+from flask.cli import with_appcontext
+
+
+@command("startapp")
+@argument("name")
+@with_appcontext
+def startapp(name: str) -> None:
+    """Create the application structure"""
+
+    if not re.match("^[a-zA-Z].*$", name):
+        raise ClickException(f"The name argument must be type of string!")
+
+    app_dir = current_app.config["SRC_DIR"] / name
+    if os.path.exists(app_dir):
+        raise ClickException("Directory {name} has already exists!")
+
+    os.mkdir(app_dir)
+
+    schema_content = """\'\'\'
+Below you write a schema of model
+Example:
+
+class ExampleSchema(ma.SQLAlchemyAutoSchema):
+    class Meta:
+        model = MODEL_NAME
+\'\'\'
+
+from ..dependencies import ma
+"""
+
+    model_content = """\'\'\'
+Below you write a model.
+Example:
+
+class Example(db.Model):
+    __tablename__ = "examples"
+
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+    title = db.Column(db.String(255), unique=True)
+
+\'\'\' 
+
+from ..dependencies import db
+"""
+
+    route_content = f"""from flask import Blueprint, make_response, jsonify, Response
+
+
+bp = Blueprint("{name}", __name__, url_prefix="/{name}")
+
+
+@bp.route("/", methods=["GET"])
+def index() -> Response:
+    return make_response(jsonify({{"hello": "{name}"}}), 200)
+"""
+
+    filenames = ["__init__.py", "schemas.py", "models.py", "routes.py"]
+    contents = ["", schema_content, model_content, route_content]
+
+    for filename, content in zip(filenames, contents):
+        with open(app_dir / filename, "w") as f:
+            f.write(content)

app/config.py

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+from pathlib import Path
+
+
+class Config:
+    TESTING = False
+    DB_SERVER = "localhost"
+    BASE_DIR = Path(__file__).resolve().parent.parent
+    SRC_DIR = BASE_DIR / "app"
+    EXCLUDED_DIRS = ["__pycache__", "commands"]
+
+    SQLALCHEMY_TRACK_MODIFICATIONS = False
+    SQLALCHEMY_DATABASE_URI = f'sqlite:///{BASE_DIR / "db.sqlite"}'
+
+
+class ProductionConfig(Config):
+    DB_SERVER = "0.0.0.0"
+
+
+class DevelopmentConfig(Config):
+    pass
+
+
+class TestingConfig(Config):
+    TESTING = True
+    SQLALCHEMY_DATABASE_URI = "sqlite:///:memory:"
+
+
+config = {
+    "development": DevelopmentConfig,
+    "production": ProductionConfig,
+    "testing": TestingConfig,
+}

app/dependencies.py

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+from flask_sqlalchemy import SQLAlchemy
+from flask_marshmallow import Marshmallow
+
+
+ma = Marshmallow()
+
+db = SQLAlchemy()

app/utils.py

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+import os
+import importlib
+import warnings
+
+from flask import current_app
+
+
+def get_app_directories() -> list:
+    directories = []
+    src_dir = current_app.config['SRC_DIR']
+    excluded_dirs = current_app.config['EXCLUDED_DIRS']
+
+    for dirname in os.listdir(src_dir):
+        path = src_dir / dirname
+        if os.path.isdir(path) and dirname not in excluded_dirs:
+            directories.append(dirname)
+    return directories
+
+
+def import_models() -> None:
+    directories = get_app_directories()
+
+    models_module = "models"
+    for dirname in directories:
+        try:
+            importlib.import_module(f"app.{dirname}.{models_module}")
+        except ModuleNotFoundError:
+            warnings.warn(f"Not found module {models_module}.py in package {dirname}")

main.py

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+from dotenv import load_dotenv
+from app import create_app
+
+if __name__ == "__main__":
+    load_dotenv()
+    app = create_app()
+    app.run()

migrations/README

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+Single-database configuration for Flask.

migrations/alembic.ini

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+# A generic, single database configuration.
+
+[alembic]
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic,flask_migrate
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[logger_flask_migrate]
+level = INFO
+handlers =
+qualname = flask_migrate
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

migrations/env.py

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+from __future__ import with_statement
+
+import logging
+from logging.config import fileConfig
+
+from flask import current_app
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+fileConfig(config.config_file_name)
+logger = logging.getLogger('alembic.env')
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+config.set_main_option(
+    'sqlalchemy.url',
+    str(current_app.extensions['migrate'].db.get_engine().url).replace(
+        '%', '%%'))
+target_metadata = current_app.extensions['migrate'].db.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline():
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url, target_metadata=target_metadata, literal_binds=True
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+
+    # this callback is used to prevent an auto-migration from being generated
+    # when there are no changes to the schema
+    # reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
+    def process_revision_directives(context, revision, directives):
+        if getattr(config.cmd_opts, 'autogenerate', False):
+            script = directives[0]
+            if script.upgrade_ops.is_empty():
+                directives[:] = []
+                logger.info('No changes in schema detected.')
+
+    connectable = current_app.extensions['migrate'].db.get_engine()
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+            process_revision_directives=process_revision_directives,
+            **current_app.extensions['migrate'].configure_args
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/script.py.mako

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+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

requirements.txt

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+alembic==1.7.7
+attrs==21.4.0
+click==8.1.3
+Flask==2.1.2
+flask-marshmallow==0.14.0
+Flask-Migrate==3.1.0
+Flask-SQLAlchemy==2.5.1
+greenlet==1.1.2
+importlib-metadata==4.11.3
+importlib-resources==5.7.1
+iniconfig==1.1.1
+itsdangerous==2.1.2
+Jinja2==3.1.2
+Mako==1.2.0
+MarkupSafe==2.1.1
+marshmallow==3.15.0
+marshmallow-sqlalchemy==0.28.0
+mccabe==0.6.1
+packaging==21.3
+pluggy==1.0.0
+py==1.11.0
+pycodestyle==2.8.0
+pyflakes==2.4.0
+pyparsing==3.0.9
+pytest==7.1.2
+pytest-flask==1.2.0
+python-dotenv==0.20.0
+six==1.16.0
+SQLAlchemy==1.4.36
+tomli==2.0.1
+Werkzeug==2.1.2
+zipp==3.8.0

tests/conftest.py

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+from typing import Generator
+
+import pytest
+from flask import Flask
+from flask.testing import FlaskClient
+
+from app import create_app
+
+
+@pytest.fixture()
+def app() -> Generator[Flask, None, None]:
+    app = create_app("testing")
+    yield app
+
+
+@pytest.fixture()
+def client(app: Flask) -> FlaskClient:
+    return app.test_client()

tests/test_example.py

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+def test_comparing_two_number():
+    assert 1 == 1