a-amato3 / calculator-api

Calculator API

This is a simple calculator API built using NestJS framework. It provides a single endpoint /calculator/calculate to perform basic arithmetic operations on two operands.

Implementation Rationale

The implementation of the calculator API follows a basic approach. The CalculatorController class defines a single POST endpoint /calculate which accepts a JSON body containing two operands and the desired operation. The controller performs the requested operation and returns the result as a JSON response.

The implementation of the solution in the provided code aims to perform basic arithmetic calculations based on the operands and operation received in the request payload. Here is a rationale for the decisions made:

• A request and response interface were made to be used in the controller from a dto

• Destructuring the CalculatorRequest Object: The code starts by destructuring the CalculatorRequest object received in the request body from the dto file. This gives easy access to the operand1, operand2, and operation values, making the code more readable.

• Handling the Operation: The code used a switch statement to quickly switch between a given operational value value. This approach provides a clear and easy way to handle different arithmetic operations. Each case calculates the result by applying the respective operation to the operands.

• Returning the Response: Finally, the response object is returned to the client, containing the problem as well as the solution. This allows the client to retrieve the calculated result of the requested arithmetic operation.

• Unit tests: The 'calculator.controller.spec' file has a test case for all four operations as well as an invalid operation.

Usage

npm run start

1. Start the app with 'npm run start':

2. By default, the API server runs on http://localhost:3000. You can access the calculator endpoint at http://localhost:3000/calculator/calculate.

3. Use cURL or Postman to send a POST request to the /calculator/calculate endpoint with the following payload:

curl -X POST -H "Content-Type: application/json" -d '{
  "operand1": 10, "operand2": 5, "operation": "+"
  }' http://localhost:3000/calculator/calculate

Replace the values of operand1, operand2, and operation as per your calculation requirements.

4. The API will respond with a JSON object containing the problem (the operands and operation) and the solution (the calculated result).

Examples

Addition

To perform an addition calculation, send a POST request to /calculator/calculate with the following payload:

{
  "operand1": 10,
  "operand2": 5,
  "operation": "+"
}

The API response will be:

{
  "problem": {
    "op1": 10,
    "op2": 5,
    "operation": "+"
  },
  "solution": 15
}

Subtraction

To perform a subtraction calculation, send a POST request to /calculator/calculate with the following payload:

{
  "operand1": 10,
  "operand2": 5,
  "operation": "-"
}

The API response will be:

{
  "problem": {
    "op1": 10,
    "op2": 5,
    "operation": "-"
  },
  "solution": 5
}

Multiplication

To perform a multiplication calculation, send a POST request to /calculator/calculate with the following payload:

{
  "operand1": 10,
  "operand2": 5,
  "operation": "*"
}

The API response will be:

{
  "problem": {
    "op1": 10,
    "op2": 5,
    "operation": "*"
  },
  "solution": 50
}

Division

To perform a division calculation, send a POST request to /calculator/calculate with the following payload:

{
  "operand1": 10,
  "operand2": 5,
  "operation": "/"
}

The API response will be:

{
  "problem": {
    "op1": 10,
    "op2": 5,
    "operation": "/"
  },
  "solution": 2
}