Helper Functions

There are a few helper functions that are used throughout the codebase. These functions are defined in /src/helpers.py.

It is recommended to define new endpoints in /src/app.py, and define any helper functions in /src/helpers.py to keep the codebase organized.

Our main helper function is get_info(). This function takes no input, but returns the same json object that the /data endpoint returns. Every other endpoints data is just taken from this larger json object.

The function does the following:

Obtain zip_code and api_key

Query strings are accessed through the flask request object.
```
zipcode = request.args.get("zipcode")
read_key = request.args.get("read_key")
```
A query string is anything after a ? in the url. They have a name, value, and separated by a &.

If the zipcode or read key is not provided, we return an error message.
Convert zipcode into lat/long and create binding box.

To convert a zipcode, we have a lookup table called ZIP_DICT. Access it using lat,lng = ZIP_DICT[zipcode]

Another helper function is already defined to create the binding box. It returns a tuple of the northeast, northwest, southeast, and southwest coordinates of the box.
```
nwlat,nwlng,selat,selng = get_binding_box(lat,lng,RANGE)
```
Create the url to ping PurpleAir with.

To provide PurpleAir with the bounding box and the many other fields we want, we use the requests.get() function from the requests library. The function allows us to pass an url and a dictionary of query parameters.

There is a helper function to create the params dictionary for you, but it may be removed due to redundancy. My suggestion is to use the following code blocks as a guide.
```
# base url
url = "https://www.api.purpleair.com/v1/sensors/"
# dictionary of parameters we want to access
params = {
    "fields": "sensor_index,latitude,longitude,temperature,IAQI",
    "key": read_key,
    "nwlat": nwlat,
    "nwlng": nwlng,
    "selat": selat,
    "selng": selng,
}
response = requests.get(url, params=params)
```
NOTE

If we are to move away from using purpleair as our data source, we can simply change the url and the contents of the params dictionary.
Create the dictionary of data to be returned.

A dictionary named scores is created and the data to be returned is inserted. This is what the function ultimately returns to the end user.

If no sensors are found, we return an error message. Otherwise, we take the returned sensor data and format it accordingly to be returned.

To send data back as a json object, we use the jsonify() function from the flask library.

@api.route("/example")
def example():
    return jsonify({
        "IAQI": IAQI,
        "zipcode": zipcode
    })

Creating a new helper function

Navigate to ./src/helpers.py.
Define a new function which (ideally) is a refactoring of code that would otherwise be put in ./src/app.py.

For example, we defined a function to ping the PurpleAir API, converting zipcodes to their coordinates and creating bounding boxes for those coordinates. The logic of our API has been factored out into ./src/helpers.py. We use these functions for simplicity and keeping the main ./src/app.py clean.
Use function in ./src/app.py.

All functions defined within ./src/helpers.py are imported into ./src/app.py for you. There is no need to import the function manually. Use as necessary.

Cool Corridors Documentation

Helper Functions

Creating a new helper function