MongoDB user Praise function theory realization [reprint]

Stores an array of _id for the user who likes the article in the posts (article) collection, for example:

posts{    _id:objectid (' 4e7020cb7cac81af7136236b '),    users_like_this_post: [        ObjectID (' 4e7020cb7cac81af71362361 '),        ObjectID (' 4e7020cb7cac81af71362362 ')    }

Check an article that likes the user:

Post = Db.posts.findOne ({_id:objectid (' 4e7020cb7cac81af7136236b ')}); Console.log (Post.users_like_this_post);

Check an article for the number of likes:

Post = Db.posts.findOne ({_id:objectid (' 4e7020cb7cac81af7136236b ')}); Console.log (post.users_like_this_post.length );

　　

Posts that have liked 100:

Posts = Db.posts.find ({' users_like_this_post.100 ': {$exists: true}});

　　

Check the user-liked article:

Posts = Db.posts.find ({users_like_this_post:user._id});

　　

User likes to post:

Db.posts.update ({_id:post._id}, {$addToSet: {users_like_this_post:user._id}});

　　

User likes to post cancel:

Db.posts.update ({_id:post._id}, {$pull: {users_like_this_post:user._id}});

　　

参考 https://segmentfault.com/q/1010000000663821

MongoDB user Praise function theory realization [reprint]