Polls challenge

How do I use it?

If you can't wait to try this api, you're at the right place. Make sure docker has File Sharing enabled for the folder.

Run:

docker-compose up

in the polls folder, wait for Docker and Maven to do their thing, then fire away.

1. List all polls created by a user

GET: http://localhost:8080/api/v1/polls/createdBy?userId=4

Challenge: make it return a 500 (one answer in the controller)

2. Search polls by its title

POST: http://localhost:8080/api/v1/polls/search

RequestBody:

{
    "title":"谁是最坏蛋奇迹超级英雄?"
}

3. List all polls created after a certain date

GET: http://localhost:8080/api/v1/polls/listFrom?fromDate=2019-06-01 - all 3 polls

GET: http://localhost:8080/api/v1/polls/listFrom?fromDate=2020-05-15 - only 2

GET: http://localhost:8080/api/v1/polls/listFrom?fromDate=2020-06-15 - none

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Getting started

Discovery

I started by registering an account on Doodle and playing around a bit with my dashboard. Creating polls, participating in them as different users, checking out the request to https://api.doodle.com/v2.2/users/me/polls and its response.

Analysys

After analyzing polls.json, I came up with the two tables I need to create to complete the tasks.

User stories

1. List all polls created by a user

Create an endpoint that takes an integer userId param and returns with an empty list or a list of polls that the user created

2. Search polls by its title

Create an endpoint that takes a string title param and returns with an empty list or a list of polls with the exact title

3. List all polls created after a certain date

Create an endpoint that takes an ISO date date in param and returns with an empty list or a list of polls with initiated post the date param. As a timestamp, the date 2020-01-01 is 2020-01-01 00:00, so an initiated timestamp of 2020-01-01 01:00 is 'after' 2020-01-01

Technology choices

Visual Studio Code + Remote Development / Dev Containers

With VS Code Remote Development, you can use a Docker container as a full-featured development environment. VS Code is going to work as if it was running locally on the Linux container I chose to develop on. Other tools offer similar solutions of course (mounting the workspace, hot-reload), but I find the extreme approach of hooking the entire "IDE" into a container quite inspiring.

To open the dev container:

• Open the folder in VS Code
• Reopen in container (popup in bottom right of the window)
• Find a Java file, hit F5
• Say yes to Java standard mode (popup in bottom right of the window)
• After a minute and the Java mode switch, you're in - now you're developing on a 'remote' machine. Move it to the cloud and you've got GitHub CodeSpaces.

More about dev containers: https://stuartleeks.com/posts/vscode-devcontainers/

Debugging inside the container:

Note: While VS Code is great for smaller Java projects, it's not mature enough for complex, multi-project Java solutions.

Spring Boot

Nothing really comes close.

PostgreSQL

Easy integration with Java, UUID as primary key natively, can index JSON objects.

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If I had more time...

I would

• Test more!
• Observability: request tracing and logging for both the DB and the service
• Performance:
  • Add an index for the title and initiated column (if we want it them be really fast)
  • Consider replacing Tomcat with Undertow (slightly better throughput afaik)
  • Based on polls.json, the database has a lot more tables than what I modeled. We could consider preloading some sort of cache storage (probably NoSQL) as the poll is created
  • Read heavy system calls for read replicas
• Refactorings:
  • Find a better home for SearchQuery.java
  • Add some sort of linting / auto formatter
  • If only I could find some automapping from Postres snake_case to camelCase...
• Nicer docker-compose: Work on making it a bit more configurable production ready, like using the devcontainer image for building and a jre image for running

What I'd do differently

• Consider dropping the ORM in favour of DTOs: While I had fun with the ORM, some queries into POJOs would have done the job much faster.
• Have much less trouble using dev containers (First time using them for Java!)
• Not forget about adding the user_id to the