Merge pull request #94 from realpython/python-sqlite-sqlalchemy

Adding the example program files that go along with the python-sqlite…

Author: writeson

python-sqlite-sqlalchemy/README.md

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+# Python / Sqlite /SqlAlchemy article
+
+This repository contains the content and example code 
+for the python/sqlite/sqlaclchemy article I'm writing 
+for Real Python.
+
+This project was built using Python 3.8.0
+
+## Installing The Project
+
+From the main folder take the following steps:
+
+* Install a Python virtual environment for this project
+* Activate the virtual environment
+* Install the project:
+
+```shell script
+python -m pip install -e .
+```
+    

python-sqlite-sqlalchemy/project/__init__.py

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+# Build Files Used By The Examples
+
+The code in this directory builds the various data files used
+by the example programs. There are three build programs:
+
+ * build_temp_data_csv.py
+ * build_temp_data_sqlite.py
+ * build_author_book_publisher_sqlite.py
+ 
+## Build the Temperature CSV File
+ 
+ The build_temp_data_csv.py file builds a CSV data file
+ (temp_data.csv) in the data directory
+ containing temperature samples taken by students in a class.
+ The top row contains the labels, the students name followed
+ by a date value for each Wednesday of the week for a year.
+ 
+ It then creates data for each sample based on a table of 
+ temperature data, +/- 10 to make the data look variable
+ and reasonable.
+ 
+## Build the Temperature Database File
+ 
+ The build_temp_data_sqlite.py file builds a Sqlite database
+ from the previously created temp_data.csv file called 
+ temp_data.db in the data directory. 
+ 
+## Build the Author / Book / Publisher Database File
+ 
+ The build_author_book_publisher_sqlite.py file builds
+ a database from the data/author_book_publisher.csv file.
+ This database contains the tables necessary to describe 
+ the data and the relationships between the data necessary
+ for the examples.
+ 
+## Directory Structure
+ 
+ The directory structure is set up in such a way the
+ build programs (as well as the examples) can find the
+ data files needed for each one.
+ 
+## Executing the Programs
+ 
+  * Activate your Python virtualenv
+  * cd into the build/code directory
+  * python build_temp_data_csv.py - builds the csv data file
+  * python build_temp_data_sqlite.py - builds the temperature data from the csv file
+  * python build_author_book_publisher_sqlite.py - builds the author_book_publisher.db database file
+  
+  
+  
+ 
+ 

python-sqlite-sqlalchemy/project/build_data/README.md

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+"""
+This program builds the author_book_publisher Sqlite database from the
+author_book_publisher.csv file.
+"""
+
+import os
+import csv
+from pkg_resources import resource_filename
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+from project.modules.models import Base
+from project.modules.models import Author
+from project.modules.models import Book
+from project.modules.models import Publisher
+
+
+def get_author_book_publisher_data(filepath):
+    """
+    This function gets the data from the csv file
+    """
+    with open(filepath) as csvfile:
+        csv_reader = csv.DictReader(csvfile)
+        data = [row for row in csv_reader]
+        return data
+
+
+def populate_database(session, author_book_publisher_data):
+    # insert the data
+    for row in author_book_publisher_data:
+
+        author = (
+            session.query(Author)
+            .filter(Author.lname == row["lname"])
+            .one_or_none()
+        )
+        if author is None:
+            author = Author(fname=row["fname"], lname=row["lname"])
+            session.add(author)
+
+        book = (
+            session.query(Book)
+            .filter(Book.title == row["title"])
+            .one_or_none()
+        )
+        if book is None:
+            book = Book(title=row["title"])
+            session.add(book)
+
+        publisher = (
+            session.query(Publisher)
+            .filter(Publisher.name == row["publisher"])
+            .one_or_none()
+        )
+        if publisher is None:
+            publisher = Publisher(name=row["publisher"])
+            session.add(publisher)
+
+        # add the items to the relationships
+        author.books.append(book)
+        author.publishers.append(publisher)
+        publisher.authors.append(author)
+        publisher.books.append(book)
+        session.commit()
+
+    session.close()
+
+
+def main():
+    print("starting")
+
+    # get the author/book/publisher data into a dictionary structure
+    csv_filepath = resource_filename(
+        "project.data", "author_book_publisher.csv"
+    )
+    author_book_publisher_data = get_author_book_publisher_data(csv_filepath)
+
+    # get the filepath to the database file
+    sqlite_filepath = resource_filename(
+        "project.data", "author_book_publisher.db"
+    )
+
+    # does the database exist?
+    if os.path.exists(sqlite_filepath):
+        os.remove(sqlite_filepath)
+
+    # create the database
+    engine = create_engine(f"sqlite:///{sqlite_filepath}")
+    Base.metadata.create_all(engine)
+    Session = sessionmaker()
+    Session.configure(bind=engine)
+    session = Session()
+    populate_database(session, author_book_publisher_data)
+
+    print("finished")
+
+
+if __name__ == "__main__":
+    main()

python-sqlite-sqlalchemy/project/build_data/__init__.py

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+import csv
+import datetime
+from random import randint
+from pkg_resources import resource_filename
+
+
+start_date = datetime.datetime.strptime("2019-01-02", "%Y-%m-%d")
+
+students = [
+    "John",
+    "Mary",
+    "Susan",
+    "Doug",
+    "Andrew",
+    "George",
+    "Martha",
+    "Paul",
+    "Helen",
+]
+
+temperature_data = [
+    10,
+    12,
+    16,
+    23,
+    13,
+    12,
+    14,
+    22,
+    25,
+    28,
+    32,
+    33,
+    37,
+    36,
+    35,
+    40,
+    44,
+    45,
+    50,
+    52,
+    58,
+    60,
+    66,
+    70,
+    70,
+    72,
+    78,
+    80,
+    81,
+    82,
+    85,
+    88,
+    90,
+    87,
+    90,
+    85,
+    82,
+    81,
+    78,
+    75,
+    72,
+    72,
+    70,
+    63,
+    65,
+    62,
+    60,
+    45,
+    40,
+    37,
+    30,
+    28,
+]
+
+
+def offset_temp(temperature):
+    """
+    This function modifies the temperature +/- a random
+    amount up to 10
+    :param temperature:     temperature to modify
+    :return:                modified temperature
+    """
+    return temperature + randint(-10, 10)
+
+
+def main():
+    # create the CSV file
+    csv_filepath = resource_filename("project.data", "temp_data.csv")
+
+    with open(csv_filepath, "w") as data_fh:
+
+        # create the writer
+        csv_writer = csv.writer(data_fh)
+
+        # write the header
+        header = ["name"]
+        for week in range(0, 52):
+            current_date = start_date + datetime.timedelta(days=week * 7)
+            header.append(current_date.strftime("%Y-%m-%d"))
+        csv_writer.writerow(header)
+
+        # iterate through the students and write their data
+        for student in students:
+            data = [student]
+            # iterate through the weeks
+            for week in range(0, 52):
+                data.append(offset_temp(temperature_data[week]))
+
+            csv_writer.writerow(data)
+
+
+if __name__ == "__main__":
+    main()

python-sqlite-sqlalchemy/project/build_data/build_author_book_publisher_sqlite.py

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+"""
+This program gathers information from the temp_data.db file about temperature
+"""
+
+import os
+import csv
+from pkg_resources import resource_filename
+from datetime import datetime
+from sqlalchemy import create_engine
+from sqlalchemy import Column, Integer, String, Date, Float
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.ext.declarative import declarative_base
+
+
+Base = declarative_base()
+
+
+class TemperatureData(Base):
+    __tablename__ = "temperature_data"
+    temperature_data_id = Column(Integer, primary_key=True)
+    name = Column(String, nullable=False)
+    date = Column(Date, nullable=False)
+    value = Column(Float, nullable=False)
+
+
+def get_temperature_data(filepath):
+    """
+    This function gets the temperature data from the csv file
+    """
+    with open(filepath) as csvfile:
+        csv_reader = csv.DictReader(csvfile)
+        data = {row["name"]: row for row in csv_reader}
+        for value in data.values():
+            value.pop("name")
+        return data
+
+
+def populate_database(session, temperature_data):
+    # insert the data
+    for student, data in temperature_data.items():
+        for date, value in data.items():
+            temp_data = TemperatureData(
+                name=student,
+                date=datetime.strptime(date, "%Y-%m-%d").date(),
+                value=value,
+            )
+            session.add(temp_data)
+        session.commit()
+    session.close()
+
+
+def main():
+    print("starting")
+
+    # get the temperature data into a dictionary structure
+    csv_filepath = resource_filename("project.data", "temp_data.csv")
+    temperature_data = get_temperature_data(csv_filepath)
+
+    # get the filepath to the database file
+    sqlite_filepath = resource_filename("project.data", "temp_data.db")
+
+    # does the database exist?
+    if os.path.exists(sqlite_filepath):
+        os.remove(sqlite_filepath)
+
+    # create and populate the sqlite database
+    engine = create_engine(f"sqlite:///{sqlite_filepath}")
+    Base.metadata.create_all(engine)
+    Session = sessionmaker()
+    Session.configure(bind=engine)
+    session = Session()
+    populate_database(session, temperature_data)
+
+    print("finished")
+
+
+if __name__ == "__main__":
+    main()

python-sqlite-sqlalchemy/project/build_data/build_temp_data_csv.py

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+fname,lname,title,publisher
+Issac,Asimov,Foundation,Random House
+Pearl,Buck,The Good Earth,Random House
+Pearl,Buck,The Good Earth,Simon & Schuster
+Tom,Clancy,The Hunt For Red October,Berkley
+Tom,Clancy,Patriot Games,Simon & Schuster
+Stephen,King,It,Random House
+Stephen,King,It,Penguin Random House
+Stephen,King,Dead Zone,Random House
+Stephen,King,The Shinning,Penguin Random House
+John,Le Carre,"Tinker, Tailor, Solider, Spy: A George Smiley Novel",Berkley
+Alex,Michaelides,The Silent Patient,Simon & Schuster
+Carol,Shaben,Into The Abyss,Simon & Schuster