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22 changes: 22 additions & 0 deletions app/__init__.py
Original file line number Diff line number Diff line change
@@ -1,7 +1,29 @@
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from dotenv import load_dotenv
import os

db = SQLAlchemy()
migrate = Migrate()
load_dotenv()

def create_app(test_config=None):
app = Flask(__name__)

if not test_config:
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
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Notice that since this option is being set in both branches of the if, it could be pulled out of the branches to either before or after the if to remove the repetition.

app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get("SQLALCHEMY_DATABASE_URI")
else:
app.config["TESTING"] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
app.config['SQLALCHEMY_DATABASE_URI'] = os.environ.get("SQLALCHEMY_TEST_DATABASE_URI")

db.init_app(app)
migrate.init_app(app, db)

# Register Blueprints
from .routes import planet_routes
app.register_blueprint(planet_routes.bp)
Comment on lines +26 to +27
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👍


return app
Empty file added app/models/__init__.py
Empty file.
39 changes: 39 additions & 0 deletions app/models/planet.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
from app import db

class Planet(db.Model):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String, nullable=False)
description = db.Column(db.String, nullable=False)
has_moon = db.Column(db.Boolean, nullable=False)
Comment on lines +5 to +7
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👍 Good column names and types. I like that you made them not nullable. For a boolean, usually being nullable is unnecessary. For strings, it can be a little more convenient, but requiring fields can make our data richer and more valuable for analysis.


def make_dict(self):
return dict(
id=self.id,
name=self.name,
description=self.description,
has_moon=self.has_moon,
)

def replace_all_details(self, data_dict):
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👍

self.name = data_dict["name"]
self.description = data_dict["description"]
self.has_moon = data_dict["has_moon"]

def replace_some_details(self, data_dict):
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👍

planet_keys = data_dict.keys()
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We don't need to retrieve the keys separately here. The in operator on dictionaries checks for a key itself, so the later checks could be written as:

    if "name" in data_dict:
        # handle name key...


if "name" in planet_keys:
self.name = data_dict["name"]
if "description" in planet_keys:
self.description = data_dict["description"]
if "has_moon" in planet_keys:
self.has_moon = data_dict["has_moon"]

# *************************
@classmethod
def from_dict(cls, data_dict):
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👍

return cls(
name = data_dict["name"],
description = data_dict["description"],
has_moon = data_dict["has_moon"]
)
2 changes: 0 additions & 2 deletions app/routes.py

This file was deleted.

Empty file added app/routes/__init__.py
Empty file.
101 changes: 101 additions & 0 deletions app/routes/planet_routes.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,101 @@
from flask import Blueprint, jsonify, abort, make_response, request
from app.models.planet import Planet
from app import db

bp = Blueprint("planets_bp",__name__, url_prefix="/planets")
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👍


# helper functions
def get_planet_record_by_id(id):
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👍

Helper looks good, including the error message helper!

try:
id = int(id)
except ValueError:
error_message(f"Invalid planet id {id}", 400)

planet = Planet.query.get(id)

if planet:
return planet

error_message(f"No planet with id {id} found", 404)

def error_message(message, status_code):
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👍

abort(make_response(jsonify(dict(details=message)), status_code))

# POST /planets
@bp.route("", methods=["POST"])
def create_planet():
request_body = request.get_json()

try:
planet = Planet.from_dict(request_body)
except KeyError as error:
error_message(f"Missing key: {error}", 400)

db.session.add(planet)
db.session.commit()
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Some food for thought that we didn't discuss in the readings: the call to commit here can also cause exceptions. Consider that we have a boolean column, but a user might pass in a string that can't be converted to a boolean. That would fail when we try to commit the record.

To avoid this, we could add additional error checking in from_dict, as well as other model helpers that update the data in a record. Or we could wrap the call to commit in a try/except and look for the exception that SQLAlchemy raises (either by checking documentation, or by forcing it to happen once to see what error we should look for).


return jsonify(planet.make_dict()), 201

# GET /planets
@bp.route("", methods=["GET"])
def list_planets():
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👍

Get all looks good. I like the function name you used too. Nice use of the list comprehension and instance method to build the dictionary for the instance.

description_param = request.args.get("description")
name_param = request.args.get("name")
has_moon_param = request.args.get("has_moon")

if description_param:
planets = Planet.query.filter_by(description=description_param)
elif name_param:
planets = Planet.query.filter_by(name=name_param)
elif has_moon_param:
planets = Planet.query.filter_by(has_moon=has_moon_param)
else:
planets = Planet.query.all()
Comment on lines +46 to +53
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Hillary, you wrote that you wanted to write this in such a way that we could filter based on some combination of parameters. To do so, we can take advantage of the fact that until we call all() or try to iterate over the results, all of these methods return objects that represent the configured query, not the result. In fact, lots of the query methods in SQLAlchemy work this way (though it's hard to tell from the docs), allowing us to chain together complex queries.

As an example of this, consider the approach below:

    planets = Planet.query
    if description_param:
        planets = planets.filter_by(description=description_param)

    if name_param:
        planets = planets.filter_by(name=name_param)

    if has_moon_param:
        planets = planets.filter_by(has_moon=has_moon_param)

    planets = planets.all()

If no filters are provided, the final line effectively becomes Planet.query.all(), but if filters are present, the chain on additional filter_by calls as needed.

This strategy could even be used to add on paging or ordering behavior!


list_of_planets = [planet.make_dict() for planet in planets]

return jsonify(list_of_planets)


# GET /planets/<planet_id>
@bp.route("/<planet_id>", methods=["GET"])
def get_planet_by_id(planet_id):
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👍

planet = get_planet_record_by_id(planet_id)

return jsonify(planet.make_dict())

# PUT /planets/<planet_id>
@bp.route("/<planet_id>", methods=["PUT"])
def replace_planet_by_id(planet_id):
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👍

request_body = request.get_json()
planet = get_planet_record_by_id(planet_id)

try:
planet.replace_all_details(request_body)
except KeyError as error:
error_message(f"Missing key: {error}", 400)

db.session.commit()

return jsonify(planet.make_dict())

# DELETE /planets/<planet_id>
@bp.route("/<planet_id>", methods=["DELETE"])
def delete_planet_by_id(planet_id):
planet = get_planet_record_by_id(planet_id)

db.session.delete(planet)
db.session.commit()

return make_response(f"Planet with id {planet_id} successfully deleted")
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Be sure to jsonify this error message. If we don't, Flask will assume we meant this to be text/html Content-Type rather than application/json. This can cause problems for clients when trying to retrieve the contents of the response.


# PATCH /planets/<planet_id>
@bp.route("/<planet_id>", methods=["PATCH"])
def update_planet_by_id(planet_id):
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👍

request_body = request.get_json()
planet = get_planet_record_by_id(planet_id)
planet.replace_some_details(request_body)

db.session.commit()

return jsonify(planet.make_dict())
1 change: 1 addition & 0 deletions migrations/README
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Generic single-database configuration.
45 changes: 45 additions & 0 deletions migrations/alembic.ini
Original file line number Diff line number Diff line change
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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

[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

[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
96 changes: 96 additions & 0 deletions migrations/env.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,96 @@
from __future__ import with_statement

import logging
from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool
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.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 = engine_from_config(
config.get_section(config.config_ini_section),
prefix='sqlalchemy.',
poolclass=pool.NullPool,
)

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()
24 changes: 24 additions & 0 deletions migrations/script.py.mako
Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
"""${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"}
34 changes: 34 additions & 0 deletions migrations/versions/0909b759653b_add_planet_model.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
"""add planet model
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👍 Good description for this migration


Revision ID: 0909b759653b
Revises:
Create Date: 2022-04-30 22:05:20.168921

"""
from alembic import op
import sqlalchemy as sa


# revision identifiers, used by Alembic.
revision = '0909b759653b'
down_revision = None
branch_labels = None
depends_on = None


def upgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.create_table('planet',
sa.Column('id', sa.Integer(), autoincrement=True, nullable=False),
sa.Column('name', sa.String(), nullable=False),
sa.Column('description', sa.String(), nullable=False),
sa.Column('has_moon', sa.Boolean(), nullable=False),
sa.PrimaryKeyConstraint('id')
)
# ### end Alembic commands ###


def downgrade():
# ### commands auto generated by Alembic - please adjust! ###
op.drop_table('planet')
# ### end Alembic commands ###
Empty file added tests/__init__.py
Empty file.
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