Laravel - 合并两个关系给出错误

Question

使用 Laravel 5.4，我有一个表 Teams 和另一个表 Matches 每场比赛都有TEAM HOME ID和TEAM AWAY ID

我发现了一个很棒的技巧，可以在这种情况下合并以查找球队在主场或客场进行的所有比赛。但它似乎不起作用。

Laravel merge reltationships

/**
 * The matches that this team has played at home.
 */
public function matchesHome()
{
    return $this->hasMany('App\Match', 'team_home_id', 'id');
}

/**
 * The matches that this team has played away.
 */
public function matchesAway()
{
    return $this->hasMany('App\Match', 'team_away_id', 'id');
}

/**
 * The matches that this team has played.
 */
public function matches()
{
    $matchesPlayedHome = $this->matchesHome();
    $matchesPlayedAway = $this->matchesAway();

    // Merge collections and return single collection.
    return $matchesPlayedHome->merge($matchesPlayedAway);     // cannot get this to work | Call to undefined method Illuminate\Database\Query\Builder::merge()
}

我得到的错误是 Call to undefined function merge 调用未定义的方法 Illuminate\Database\Query\Builder::merge()

请帮忙 谢谢

........

我什至尝试过预先加载，在这种情况下错误变成了

关系方法必须返回 Illuminate\Database\Eloquent\Relations\Relation 类型的对象

public function matches()
{
    $matches = Team::with('matchesHome', 'matchesAway')->get();
    return $matches;
}

Answer 1

我觉得你的语法有点不对：

function matches() {
  return $this->matchesHome->merge($this->matchesAway);
}

Answer 2

这就是我解决问题的方法。 $appends 在另一篇文章中的答案不清楚，所以让我在下面解释一下。

如果不给$appends添加任何方法，Laravel认为也是关系属性，报错Relationship method must return an object of type Illuminate\Database\雄辩\关系\关系

因为它正在寻找一种它没有得到的关系。这就是为什么如果我们添加 $appends 我们可以让下面的代码工作。

如果有人遇到这种情况，我就是这样解决的。

protected $appends = ['matches'];

/**
 * The matches that this team has played at home.
 */
public function matchesHome()
{
    return $this->hasMany('App\Match', 'team_home_id', 'id');
}

/**
 * The matches that this team has played away.
 */
public function matchesAway()
{
    return $this->hasMany('App\Match', 'team_away_id', 'id');
}


/**
 * This function is used by the appends to append two attributes
 */
public function getMatchesAttribute()
{
    return $this->matchesHome->merge($this->matchesAway);
}

我们也可以用 Eager loading 替换它，它会正常工作。