yaaminu / mpharma-takehome

Backend Take Home Challenge

Running

Ensure you have docker compose installed on your system and run this in the terminal

docker-compose up

This will start both the database(postgres) and the rest API. The REST api will be reachable on port 5000.

Using The REST api

The REST api allows users to create, edit, delete and view diagnostic codes. The table below summarizes the api. On success, the server returns standard http status code and on failure, the server adds an additional application specific error code to the response as described in table 2. All api responses are in json and the structure is described in table 3.

Table 1.0

Action	Method	Endpoint	Body	Notes
Create	POST	/api/v1/diagnostic_records	full_code, revision, short_desc, full_desc, category_name
Edit	PUT	/api/v1/diagnostic_records/:id	full_code?, revision?, short_desc?, full_desc?, category_name?	1. Any fields can be optional but at least one field must be submitted
Delete	DELETE	/api/v1/diagnostic_records/:id
Find By ID	GET	/api/v1/diagnostic_records/:id
List	GET	/api/v1/diagnostic_records/?page={number=1}		The server returns extra information such as the totalPageCount, currentPage, and the number of entries per page.

Table 2.0

Error code	Description
E_VALIDATION	Form validation failed
E_DUPLICATE	Attempted to add an item that already exists
E_NOT_FOUND	Attmpted to retrieve or delete a non-existing item
E_UNKNOWN	An unknown error occured

Table 3.0

name	description	notes
status	the http status code
code	the application specific error code	only available when a request errs
message	A short description of the response (useful when a request errs)
totalPageCount	the total number of pages	only for list requests (see above)
page	the current page	only for list requests
value	response data	only exists in list, findById and edit requests
err	When a requests errs, the server sends the error stack to the client	only in development mode

Example api requests requests

1. Create a new diagnostic code

 `curl http://{host}:{port}/api/v1/diagnostic_codes -X POST -d category_name="example category" -d full_desc="Full description" -d short_desc="   Short description" -d full_code="A02.29" -d revision=" ICD-10`

2. Edit an exisiting diagnostic code

 `curl http://{host}:{port}/api/v1/diagnostic_codes/:id -X PUT -d full_code=A02.1`
 changes the full_code to A02.1

3. Delete a diagnostic code

 `curl http://{host}:{port}/api/v1/diagnostic_codes/:id -X DELETE`

4. Find a diagnostic code by id

 `curl http://{host}:{port}/api/v1/diagnostic_codes/:id`

5. List at most the first 20 diagnostic codes

 `curl http://{host}:{port}/api/v1/diagnostic_codes/?page=1`

6. List at most the second 20 diagnostic codes

 `curl http://{host}:{port}/api/v1/diagnostic_codes/?page=2`

6. List at most the first 5 diagnostic codes

 `curl http://{host}:{port}/api/v1/diagnostic_codes/?page=1&limit=5`

Testing

1. Ensure that there's a running postgres instance

2. A database named mpharma exists

3. A postgres user named postgres with password postgres exists

4. Jump into the project root and run the following in your terminal:

    npm install npx typescript -g 
    npm install
    npm run migrate
    npm test 

NOTE All the http routes were tested manually for brevity sake.

Technical Consideration

ICD-10 vs ICD-9 incompatibility

The new ICD-10 introduced some backward incompatible changes. However that change matters if one relies on the semantics in the code. I decided against that and just treated all codes as a series of charaters and required the version to be explictly specified by the user. Offloading that burden to the user simplified the system. To ensure users don't supply invalid codes, I implemented a rudimentary checks to ensure that supplied codes match with the version specified.

However, the tradeoff is that it'll be more challenging to take advantage of the semantic meanings embeded in the codes in the future assuming this were a real project.

Pagination

Pagination is controlled by the user and they are allowed to change entries per page. More importantly tho, the records are sorted by id to ensure the odering is stable (since users can't change the id).