Python

Zero allows you to define your API endpoints as individual functions. Each such function resides in it's own file. The function should be named handler. If your function resides in ./api/process.py file, it's exposed at http://<SERVER>/api/process.

Zero uses flask internally. Which means you can use any of the awesome flask imports like jsonify and request.

Example

# hello.py
def handler():
  return "Hello"

The above file exports a function named handler. When you visit http://127.0.0.1:3000/hello, Zero calls handler() and the response is sent back to browser.

Before You Start

You must install Python3 before using Zero for Python.

Printing To Console

It's common to use print() for debugging. You must use flush=True for your print statements to work. Like this: print("Hello", flush=True)

JSON Response

APIs usually respond in JSON format. This means you can use flask's jsonify module to create JSON response.

Example

from flask import jsonify
def handler():
  arr = [1, 2, 3]
  return jsonify(
      username="basic",
      email="[email protected]",
      arr=arr
  )

URL Parameters

Here is an example of how to get URL parameters sent by browser (the ?id=1&.... part of URL) in your Python handler:

# hello.py
from flask import request
def handler():
  name = request.args.get('name')
  return "Hello, " + name

Visiting http://127.0.0.1:3000/hello?name=luke will now print Hello, luke.

Requirements.txt

Zero can auto-install dependencies using pip. Just add a requirements.txt file to your project root.

Example

numpy==1.15.0
pandas==0.20.3

Dynamic Routes (Pretty URL Slugs)

Zero decides routes based on file structure. Most projects also require dynamic routes like /user/luke and /user/anakin. Where luke and anakin are parameters. Zero natively supports this type of routes: any file or folder that starts with $ is considered a dynamic route.

So if you create ./user/$username.py and then from browser visit /user/luke, Zero will send that request to $username.py file and your handler should accept a username argument. Code for this:

# project/
# └── user/
#     └── $username.js <- this file
def handler(username):
  return "Hello, " + username

Parameters apply to folder-names too. Another example: if you want to cater /user/luke/messages route, you can handle this with following directory structure:

project/
└── user/
    └── $username/
        └── index.py
        └── messages.py

index.py handles /user/:username routes.
messages.py handles /user/:username/messages routes.

You can also have nested dynamic paths like /user/:username/:commentId with a handler in ./user/$username/$commentId with the following code:

def handler(username, commentId):
  return username + " says: " + getComment(commentId)

Tip: $ is used by Bash for variables. So it might be confusing when you do cd $username or mkdir $username and nothing happens. The right way to do this is escaping the $ ie. cd $username or mkdir $username.

POST Data

Here is an example of how to get POST data (sent from an HTML form) in your Python handler:

# login.py
from flask import request
def handler():
  if request.method == 'POST':
    email = request.form.get('email')
    password = request.form.get('password')
    if password == "secretpassword":
      return "Success"
  return "Failed"

Here is an example HTML form:

<!-- index.html -->
<html>
  <body>
    <form action="/login" method="POST">
      <input type="email" name="email" />
      <input type="password" name="password" />
      <input type="submit" />
    </form>
  </body>
</html>

File Upload

Here is an example of how to handle file upload in your Python handler:

# upload.py
from flask import request
from werkzeug import secure_filename
def handler():
  if request.method == 'POST':
    f = request.files['file']
    f.save(secure_filename(f.filename))
    return 'file uploaded successfully'

Here is an example HTML form to send file to your API:

<!-- index.html -->
<html>
  <body>
    <form action="/upload" method="POST" enctype="multipart/form-data">
      <input type="file" name="file" />
      <input type="submit" />
    </form>
  </body>
</html>

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