The File Generator

About

• This is an application (web-service) that allows one to generate and download file(excel for now) based on dynamic number of columns(headers) at runtime and certain configuration values such as prefix, postfix, and some values as per the users' requirements.
• This is the backend service available at the endpoint /api/v1/fileGenerator/download which receives the payload that differs from one user to another user at run time. Payload example is as follows:

  
  {
  "fileType": "",
  "headers": {
      "email": {
          "type": "email",
          "prefix": "abc",
          "postfix": "abc.io",
          "value": "demoemail"
      },
      "phone": {
          "type": "phone",
          "prefix": "+977",
          "value": "9867612345"
      },
      "name": {
          "type": "name",
          "prefix": "John",
          "postfix": "Doe",
          "value": "Demo"
      },
      "address": {
          "type": "string",
          "prefix": "BGL-",
          "value": "Nepal"
      },
      "dummy": {
          "type": "",
          "prefix": "",
          "postfix": ""
      }
  },
  "noOfRecords": 20
  }

Challenges

• Since, the number of items inside the "headers" payload dynamically grow and shrink based on the user's requirements, it is very hard to determine and return the exact type or the exact format while filling the excel file. For instance, when user adds address as the name of of the header column, not sure how to determine the value for this column(definitely it does, I am just talking about the exact format of the data not just some random string value). Furthermore, using if else is cumbersome and it never meets the requirements for all the possible values that users may enter. Another example could be, let us say user entered the completely uncommon header, then addressing with if else also becomes almost not feasible and type of data would just look too random and additionally not meaningful even though it will contain some type of random data.
• It works perfectly now, just the exact desired value when user doesn't fill some prefix, postfix values on the app, i.e just enters the column name, and nothing else, that time, it is very hard to know what format of data user wants.
  
  

Further work

• Work can be done with slight modification to generate csv file. In additon to this, it can also be made for pdf file generation.
• Is there any proper work that can address the above problem ?
• Can we make some logic and implement it in a method to accommodate most of the data types ? It would be nice if it returns some meaningful formatted values for columns other than those explicitly handled.
  
  

Postmand Request and Response Example

1. In the screenshot example above, inside of the headers key, we have other nested keys, namely, email, phone, name, address, dummy and these are essentially excel files' header name.
2. This key will be as many as we put and headers will be generated accordingly.
3. Inside of the each key, we have other key such as type, prefix, postfix, these are fundamentally, extra configurations for the value of the header to be generated. For instance, if email has following structure :

   {
   "email" : {
     "type" : "email",
     "prefix": "cse-",
     "postfix" : "ubc.com",
     "value": "some_value"
   }
   }

   In such case, one of the example emails which would be generated is cse-111222@ubc.com, where 111222 will be some randomly generated value. If we include value as well, it will just be appended to the prefix.

Example CURL request

Either run locally or pull the docker image and hit the following request

• To pull the docker image from docker hub, use following command:

  docker pull badripaudel77/dynamic-excel-generator

• To run the docker image, run the following command

  docker run -p 8080:8080 badripaudel77/dynamic-excel-generator:latest

• Finally, send the CURL request to run the application as follows:

  curl -X POST http://localhost:8080/api/v1/fileGenerator/download \
  -H "Content-Type: application/json" \
  -d '{
  "fileType": "",
  "headers": {
      "email": {
          "type": "email",
          "prefix": "abc",
          "postfix": "abc.io",
          "value": "demoemail"
      },
      "phone": {
          "type": "phone",
          "prefix": "+977",
          "value": "9867612345"
      },
      "name": {
          "type": "name",
          "prefix": "John",
          "postfix": "Doe",
          "value": "Demo"
      },
      "address": {
          "type": "string",
          "prefix": "BGL-",
          "value": "Nepal"
      },
      "dummy": {
          "type": "",
          "prefix": "",
          "postfix": ""
      }
  },
  "noOfRecords": 20
  }'