php - laravel belongstomany 有条件

Question

我有以下模型。

class Training extends \Eloquent {

    // Add your validation rules here
    public static $rules = [
        'name' => 'required',
        'city' => 'required',
        'province' => 'required',
        'budget_year' => 'required|integer',
        's_date' => 'required|date',
        'e_date' => 'required|date'
    ];

    // Don't forget to fill this array
    protected $fillable = [
        'name',
        'city',
        'province',
        'budget_year',
        's_date',
        'e_date'
    ];

    public function material(){
        return $this->hasMany('Material');
    }

    public function budget(){
        return $this->belongsToMany('Budget')->withPivot('amount');
    }

    public function budgetById($training_id){
        $this->belongsToMany('Budget')->where('training_id', '=', $training_id)->get();
    }

}

当我使用DB::getQueryLog调试budgetById方法时，查询如下

select budgets.*, 
budget_training.training_id as pivot_training_id, 
budget_training.budget_id as pivot_budget_id 
from budgets inner join budget_training on budgets.id = budget_training.budget_id 
where budget_training.training_id is null and training_id='6'

它返回 0 行，但是当我尝试修改查询并在 pgadmin 中运行它时，以下脚本运行良好。

select budgets.*, 
budget_training.training_id as pivot_training_id, 
budget_training.budget_id as pivot_budget_id 
from budgets inner join budget_training on budgets.id = budget_training.budget_id 
where budget_training.training_id='6'

注意我从 Laravel 生成的查询中删除了 training_id is null and。我的 budgetById 方法有什么问题？

Answer 1

你已经调用了 get() 而没有在这里使用 return:

public function budgetById($training_id){
    // = in where is optional in this case
    $this->belongsToMany('Budget')->where('training_id', '=', $training_id);
}

你应该这样使用:

public function budgetById($training_id){
    // = in where is optional in this case
    return $this->belongsToMany('Budget')->where('training_id', '=', $training_id);
}