Laravel加入3桌

本文介绍了Laravel加入3桌的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 我正在建立一个类似Twitter的应用程式。有一个Feed，我只想显示我关注的用户的帖子。 我尝试了所有的连接，但没有什么似乎工作。 我有3个表： c >。 示例 $ shares = DB :: table（'shares'） - > join（'users'，'users.id'，'='，'shares.user_id'） - > join（'follows'，'follows.user_id'，'='，'users.id'） - > where（'follows.follower_id'，'='，3） - > get（）; 模型方法 实现你使用 DB :: 查询而不是模型。所以我修复答案，并提供了更多的清晰度。我建议你使用模型，对于那些以框架和特别的SQL开头的人来说，这很容易。 模型示例 class User extends Model { public function shares（$ { return $ this- > hasMany（'Share'）; } public function followers（）{ return $ this-> belongsToMany（'User'，'follows'，'user_id'，'follower_id'）; } public function followees（）{ return $ this-> belongsToMany（'User'，'follows'，'follower_id'，'user_id'）; } } class Share扩展模型{ public function user（）{ return $ this-> belongsTo（'User'）; } } 模型用法示例： $ my = User :: find（'my_id'）; //按照我的用户检索所有共享 //希望加载共享的所有者 $ shares = Share :: with（'user'） - > join（'follows'，'follows.user_id'，'='，'shares.user_id'） - > where（'follows.follower_id'，'='，$ my- > id） - > get（'shares。*'）; //注意共享。* here //输出共享内容的用户名 foreach（$ shares为$ share）{ echo $ share-> user-> username; } //检索所有正在关注的用户 $ my-> followees; //检索跟随我的所有用户 $ my-> followers; I am building a Twitter-like app. There is a Feed in which I want to only show posts of Users who I follow.I tried everything with joins, but nothing seems to work.I have 3 tables: Users, Followers, SharesThe Tables look like this:Users: idFollowers: user_id, follower_idShares: user_idWhat I need to get is "ALL Shares WHERE share.user_id = followers.follower_id""ANDWHERE followers.user_id = users.id"Assume, the users.id is 3, I tried this:$shares = DB::table('shares') ->leftjoin('followers', 'shares.user_id', '=', 'followers.follower_id') ->leftjoin('users', 'followers.user_id', '=', 'users.id') ->where('users.id', 3) ->where('shares.user_id', 'followers.follower_id') ->get();But it doesnt work.Any help is appreciated :) 解决方案 I believe your join is wrong:$shares = DB::table('shares') ->join('users', 'users.id', '=', 'shares.user_id') ->join('followers', 'followers.user_id', '=', 'users.id') ->where('followers.follower_id', '=', 3) ->get();I also suggest you to name your table as follows instead, it feels a bit more natural to say user has many followers through follows and user has many followees through follows.Example$shares = DB::table('shares') ->join('users', 'users.id', '=', 'shares.user_id') ->join('follows', 'follows.user_id', '=', 'users.id') ->where('follows.follower_id', '=', 3) ->get();Model approachI didn't realize you were using DB:: queries and not models. So I'm fixing the answer and providing a lot more clarity. I suggest you use models, it's a lot easier for those beginning with the framework and specially SQL.Example of models:class User extends Model { public function shares() { return $this->hasMany('Share'); } public function followers() { return $this->belongsToMany('User', 'follows', 'user_id', 'follower_id'); } public function followees() { return $this->belongsToMany('User', 'follows', 'follower_id', 'user_id'); }}class Share extends Model { public function user() { return $this->belongsTo('User'); }}Example of Model usage:$my = User::find('my_id');// Retrieves all shares by users that I follow// eager loading the "owner" of the share$shares = Share::with('user') ->join('follows', 'follows.user_id', '=', 'shares.user_id') ->where('follows.follower_id', '=', $my->id) ->get('shares.*'); // Notice the shares.* here// prints the username of the person who shared somethingforeach ($shares as $share) { echo $share->user->username;}// Retrieves all users I'm following$my->followees;// Retrieves all users that follows me$my->followers; 这篇关于Laravel加入3桌的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！