A relationship between users and followers is many-to-many.

My model:

type User struct {
    gorm.Model
    Username   string  `json:"username" gorm:"unique"`
    Name       string  `json:"name"`
    Followers  []*User `json:"followers" gorm:"many2many:user_followers"`
    Following  []*User `json:"following" gorm:"many2many:user_following"`
}

This model, when migrated, creates two junction tables which hold the user id and the follower/following id respectively.

Am I making a mistake by separating the Followers and Followings and in they are actually supposed to be just one table?

CodePudding user response：

I'd follow the KISS principle here and simplify the solution.

One table followers with user_from_id,user_to_id,create_at,... fields and with a (user_from_id,user_to_id) unique key should be enough. The (user_from_id,user_to_id) unique key will make sure that there are no duplicates.

Most likely you'll have 4 types of queries for this table:

1. Select current user followers ... WHERE user_to_id=%current_user_id% ...
2. Select users followed by the current user ... WHERE user_from_id=%current_user_id% ...
3. Check if the current user is following another user: ... WHERE user_from_id=%current_user_id% AND user_to_id=%another_user_id% ...
4. Check if another user is following the current user: ... WHERE user_from_id=%another_user_id% AND user_to_id=%current_user_id% ...

Cases 2,3,4 are already covered by the (user_from_id,user_to_id) unique key. However, you'll need an extra index (not unique, simple index will be enough) to optimise the 1st query: (user_to_id).

Note: you may need extra indexes to optimise queries for your table. I assumed the most common use cases.