Now, the user can add new crimes to our crime database, but we want the map to display crimes that are already added as well. To achieve this, whenever the page is loaded, our app needs to make a call to the database to get the latest crime data. We then need to pass this data to our template file, loop through each crime, and place a marker in the correct place on the map.

Now, our data is stored in a MySQL database. We will access it using Python on the server side, and we want to display it using JavaScript on the client side; so, we'll need to spend a bit of time on converting our data to the appropriate format. When we access the data through our Python pymysql driver, we will receive it as a tuple. To display the data using JavaScript, we want it in JSON. JSON, you might remember from our Headlines project, is JavaScript Object Notation, a structured data format that JavaScript can easily read and manipulate. As with our previous project, we'll...