Learn how to build a REST API with Python.

Become a Flask Developer

In this module, you will learn how to build a REST API using a lighter web framework for Python, i.e., FastAPI. You will learn the basics of FastAPI and learn how to implement parallel processing in Python APIs. 

Finally, you will deploy your API on Microsoft Azure and build a Continuous Integration/Continuous Development (CI/CD) Pipeline using Github.

Building REST API with Python

## Default query parameters 
As query parameters are not a fixed part of a path, they can be optional and can have default values. You can assign a default value to the query parameters as shown in the below code:



from fastapi import FastAPI

app = FastAPI()

course_items = [{"course_name": "Python"}, {"course_name": "NodeJS"}, {"course_name": "Machine Learning"}]

@app.get("/courses/")
def read_courses(start: int = 0, end: int = 10):
    return course_items[start : start + end]

import React from 'react';
import { shallow, configure } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

import HelloWorld from './app';

var TestResult = function() {
    this.succeeded = false;
    this.reason = "";
    this.input = "";
    this.expected_output = "";
    this.actual_output = "";
}

export const executeTests = function() {

  var results = [];

  result = new TestResult();
  result.input = 'HelloWorld Component';
  result.expected_output = "span containing text 'Hello World'"

  let wrapper = shallow(<HelloWorld />);

  // Call your Challenge function here.

  let type = wrapper.type();
  let testSuccessful = true;
  let failureReason;

  if (type !== 'span') {
    testSuccessful = false;
    failureReason = "You need to render exactly one span HTML element";
  } else if (wrapper.props().children != "Hello World") {
     testSuccessful = false;
     failureReason = "You have rendered wrong message in your span element";
  }

  result.actual_output = wrapper.html();

  if (testSuccessful) {
    result.succeeded = true;
    result.reason = "Succeeded"
  } else {
    result.succeeded = false;
    result.reason = failureReason;
  }

  results.push(result);

  return results;
}


FastAPI-test

React

Dart

GoJS React

Typescript React

Vue.js

In the example above, we have set the default values of `start = 0` and `end = 10`. So, when we go to the URL: 
```a
http://localhost:8000/courses/
```
It would be the same as going to:
```
http://localhost:8000/courses/?start=0&end=10
```
But if you go to, for example:
```a
http://localhost:8000/courses/?start=20
```
The parameter values in your function will be:
* `start = 20` because you set it in the `URL`.
* `end = 10` because that was the default value.

## Optional query parameters 
There is another way to implement query parameters by setting their default value as `None`. If you don’t want to pass the default values but want to have some optional query parameters, you can set its value to `None`. Let us see the implementation below:


# Default query parameters 
As query parameters are not a fixed part of a path, they can be optional and can have default values. You can assign a default value to the query parameters as shown in the below code:



In the example above, we have set the default values of `start = 0` and `end = 10`. So, when we go to the URL: 
```a
http://localhost:8000/courses/
```
It would be the same as going to:
```
http://localhost:8000/courses/?start=0&end=10
```
But if you go to, for example:
```a
http://localhost:8000/courses/?start=20
```
The parameter values in your function will be:
* `start = 20` because you set it in the `URL`.
* `end = 10` because that was the default value.

# Optional query parameters 
There is another way to implement query parameters by setting their default value as `None`. If you don’t want to pass the default values but want to have some optional query parameters, you can set its value to `None`. Let us see the implementation below:


Learn and implement default and optional query parameters using FastAPI.

Before We Begin

Building Blocks of an API in Python

Learn the Basics of FastAPI

Optical Character Recognition API Using Tesseract - Project 1

Cloud and Microsoft Azure Services

Text Analytics API Using Azure Cognitive Services - Project 2

Deploy the REST API on Microsoft Azure

Conclusion

Appendix

Default and Optional Query Parameters in FastAPI

Default query parameters