Laravel属于ToMany，无法解决它

Question

I have a jokes, joke_tags, tags table. And I'm trying to get all tags that match the joke ID.

class Joke extends Model
{
    public function tags() {
        return $this->belongsToMany('App\Tag', 'joke_tags', 'tag_id', 'joke_id');
    }
}

My Tag model:

class Tag extends Model
{
    public function jokes() {
        return $this->belongsToMany('App\Joke');
    }
}

Both functions tags() and jokes() don't work... I've been struggling with that for 2 hours now.

My db layout:

Schema::create('jokes', function (Blueprint $table) {
    $table->increments('ID');
    $table->string('author');
    $table->longText('joke');
    $table->timestamps();
});

Schema::create('joke_tags', function (Blueprint $table) {
    $table->increments('ID');
    $table->integer('joke_id')->unsigned();
    $table->foreign('joke_id')->references('ID')->on('jokes');
    $table->integer('tag_id')->unsigned();
    $table->foreign('tag_id')->references('ID')->on('tags');
});

Schema::create('joke_votes', function (Blueprint $table) {
    $table->increments('ID');
    $table->integer('joke_id')->unsigned();
    $table->foreign('joke_id')->references('ID')->on('jokes');
    $table->string('IP');
    $table->boolean('type');
});

Schema::create('tags', function (Blueprint $table) {
    $table->increments('ID');
    $table->string('tag');
});

Answer 1

Add this to both of your models and you would be good to go.

protected $primaryKey = 'ID';

EDIT: You should define the relationships as follows besides adding the above property.

class Joke extends Model
{
    public function tags() {
        return $this->belongsToMany('App\Tag', 'joke_tags', 'joke_id', 'tag_id');
    }
}

class Tag extends Model
{
    public function jokes() {
        return $this->belongsToMany('App\Joke', 'joke_tags', 'tag_id', 'joke_id');
    }
}