Database-Workstop

Today we'll go over how to set up a database using Flask and Flask-SQLAlchemy and connect it to a simple web app. Before we begin, clone this repository into a local directory that you want to use for this project. Also, make sure you have the latest versions of Python and virtualenv installed. If you haven't downloaded them yet, you can visit this link for Python: https://www.python.org/downloads/ and follow the instructions below for virtualenv.

Installing Virtualenv

Run this command in your terminal to install virtualenv:

pip install virtualenv

Installing Flask and Flask-SQLAlchemy

1. Open your terminal and create a virtual environment. We want to install dependencies in a virtual environment because different projects that you may be working on might require different versions of the dependencies that you're using. Using a virtual environment ensures that you always have the right dependencies for your current project. Run the following command to create your virtual environment.

   For macOS/Linux:

   python3 -m venv venv
   

   For Windows:

   py -3 -m venv venv
   

2. Then, activate your virtual environment:

   For macOS/Linux:

   . venv/bin/activate
   

   For Windows:

   venv\Scripts\activate
   

3. Finally, run the following lines to install Flask and Flask-SQLAlchemy using pip:

   pip install Flask
   pip install -U Flask-SQLAlchemy
   

Creating a Basic Web App

1. Take a look at the files in your directory, starter.py and the templates and static folders.

   starter.py contains a basic Flask application that creates a simple database and displays the content and formatting from templates and static.

2. Now let's take a look at our rudimentary web app. From your project directory, run the following command and go to localhost:5000 to take a look:

   For macOS/Linux:

   python3 starter.py
   

   For Windows:

   py starter.py
   

   If you try to add any groceries, you'll see that you get an error. Before using the grocery list, the functions in starter.py must be fully implemented.

3. Now take a closer look at starter.py. This file includes several imports and defines a Flask app, SQL database, Grocery class, and several functions for the grocery list. Start fixing the web app by filling in the blanks for the imcomplete functions.

4. First, implement the post request in the index function. In this function, you need to capture the input from the user-submitted form and make a grocery object out of the submitted info.

   Add the grocery item to the update (similar to how you would stage a git commit).

   Then, commit that change to the database and redirect back to the homepage of the web app.

5. Next, implement the delete function.

   This function gets an element from the database and deletes it from the database (HINT: think about how to identify items on the list without using its name).

   Then commit your changes and redirect back to the homepage, just like you did in the previous function.

6. Finally, implement the update function.

   Using what you've learned from the previous two functions, update an item in the database (HINT: this function aims to update an object's contents. Think of each grocery item as an entry in a dictionary).

Conclusion

Now you're done! That's the basic rundown of how to set up a Flask app using a SQL database through Flask-SQLAlchemy. Even if your team might not be using Flask, take a look as you might be implementing something similar in your project.

For a bonus challenge, suppose we needed to know how much of each item we need on our grocery list. Add an amount column to the Grocery object and implement it into your functions.

If you'd like to see the solutions for yourself, switch over to the solution branch and look inside app.py for the complete version of starter.py.