Make number of Likes limited to user x post relationship

[anlsergio]

The "LikePost" feature allows a single user to add likes to a single post as much as he pleases, so it requires a more complex structure in order to ensure that a post can only be liked once by a single user.

Suggestion:

• Database: The database requires another table to store Users' foreign keys and Posts' foreign keys in order to create an N x N relationship between Users and Posts (this makes it possible also to add more fancy features like fetching a list of the users that currently like the post);
• Code: Additional logic must be put in place to validate if a given post is already liked by a given user;
• Unlike: Of course the "UnlikePost" feature should have the same approach applied so that a single user isn't able to indefinitely unlike a post.

Disclaimer: it's not flagged as a bug because it was thought to be simple initially but it's a great enhancement suggestion for the future.