我正在学习CakePHP，但在处理关联的方式上遇到了一些问题（可能只是我的误解）。我有一个RESULTS表，它有一个由表WORKSHEETS和STUDENTS的两个外键组成的复合键。下面是RESULTS、Worksheets和Students之间的关系。
结果N - 1学生
结果N - 1工作表
Data Schema here
我的问题是，RESULTS表的搭建ADD页没有显示STUDENTS和WORKSHEETS的<select>字段。
首先，这是results/add.php页面的HTML，由Form-〉控件生成。STUDENT和WORKSHEET的两个输入不是Select，而是隐藏的输入。

<input type="hidden" name="student_id" options="(object)Cake\Datasource\ResultSetDecorator" id="student-id"/>
<input type="hidden" name="worksheet_id" options="(object)Cake\Datasource\ResultSetDecorator" id="worksheet-id"/>
<div class="input text">
<label for="result">Result</label>
<input type="text" name="result" id="result" maxlength="6"/></div>

<button type="submit">Submit</button>

下面是为ResultsTable.php搭建的initialize（）代码：

$this->setTable('results');
    $this->setDisplayField(['student_id', 'worksheet_id']);
    $this->setPrimaryKey(['student_id', 'worksheet_id']);

    $this->addBehavior('Timestamp');

    $this->belongsTo('Students', [
            'foreignKey' => 'student_id',
            'joinType' => 'INNER',
    ]);
    $this->belongsTo('Worksheets', [
            'foreignKey' => 'worksheet_id',
            'joinType' => 'INNER',
    ]);

下面是add.php中的表单控件生成（前两行在搭建过程中甚至没有添加）。

echo $this->Form->control('student_id', ['options' => $students]);
   echo $this->Form->control('worksheet_id', ['options' => $worksheets]);
   echo $this->Form->control('result');

下面是控制器中add函数的最后一部分：

$students = $this->Results->Students->find('list', ['limit' => 200])->all();
  $worksheets = $this->Results->Worksheets->find('list', ['limit' => 200])->all();
  $this->set(compact('result', 'students', 'worksheets'));

初始化（）

$this->setTable('students');
        $this->setDisplayField('name');
        $this->setPrimaryKey('id');

        $this->addBehavior('Timestamp');

        $this->belongsTo('Ranks', [
            'foreignKey' => 'rank_id',
        ]);
        $this->belongsTo('Grades', [
            'foreignKey' => 'grade_id',
            'joinType' => 'INNER',
        ]);
        $this->hasMany('Results', [
            'foreignKey' => 'student_id',
        ]);

初始化（）

$this->setTable('worksheets');
        $this->setDisplayField('id');
        $this->setPrimaryKey('id');

        $this->addBehavior('Timestamp');

        $this->belongsTo('Subranks', [
            'foreignKey' => 'subrank_id',
            'joinType' => 'INNER',
        ]);
        $this->hasMany('Results', [
            'foreignKey' => 'worksheet_id',
        ]);
    }

关于为什么会发生这种情况的一些提示？
如果您需要任何其他信息或代码，请告诉我。
PS：具有belongsTo关系的所有其他表都已正确搭建，并具有正确的<select>字段。
调试（$workesks）输出：

ROOT\templates\Results\add.php (line 8)
object(Cake\Datasource\ResultSetDecorator) id:0 {
'count' => (int) 12
}

调试（$students）输出：

ROOT\templates\Results\add.php (line 10)
object(Cake\Datasource\ResultSetDecorator) id:0 {
  'count' => (int) 2
}

从控制器的add方法中删除-〉all（）后，得到一个查询对象，如下所示：

ROOT\templates\Results\add.php (line 10)
object(Cake\ORM\Query) id:0 {
  '(help)' => 'This is a Query object, to get the results execute or iterate it.'
  'sql' => 'SELECT Students.id AS Students__id, Students.name AS Students__name FROM students Students LIMIT 200'
  'params' => [
  ]
  'defaultTypes' => [
    'Students__id' => 'integer',
    'Students.id' => 'integer',
    'id' => 'integer',
    'Students__student_number' => 'string',
    'Students.student_number' => 'string',
    'student_number' => 'string',
    'Students__name' => 'string',
    'Students.name' => 'string',
    'name' => 'string',
    'Students__rank_id' => 'integer',
    'Students.rank_id' => 'integer',
    'rank_id' => 'integer',
    'Students__worksheets_count' => 'integer',
    'Students.worksheets_count' => 'integer',
    'worksheets_count' => 'integer',
    'Students__perfects_count' => 'integer',
    'Students.perfects_count' => 'integer',
    'perfects_count' => 'integer',
    'Students__accuracy_rate' => 'integer',
    'Students.accuracy_rate' => 'integer',
    'accuracy_rate' => 'integer',
    'Students__created' => 'date',
    'Students.created' => 'date',
    'created' => 'date',
    'Students__modified' => 'date',
    'Students.modified' => 'date',
    'modified' => 'date',
    'Students__email' => 'string',
    'Students.email' => 'string',
    'email' => 'string',
    'Students__password' => 'string',
    'Students.password' => 'string',
    'password' => 'string',
    'Students__grade_id' => 'integer',
    'Students.grade_id' => 'integer',
    'grade_id' => 'integer',
  ]
  'decorators' => (int) 0
  'executed' => false
  'hydrate' => true
  'buffered' => true
  'formatters' => (int) 1
  'mapReducers' => (int) 0
  'contain' => [
  ]
  'matching' => [
  ]
  'extraOptions' => [
  ]
  'repository' => object(App\Model\Table\StudentsTable) id:1 {
    'registryAlias' => 'Students'
    'table' => 'students'
    'alias' => 'Students'
    'entityClass' => 'App\Model\Entity\Student'
    'associations' => [
      (int) 0 => 'Ranks',
      (int) 1 => 'Grades',
      (int) 2 => 'Results',
    ]
    'behaviors' => [
      (int) 0 => 'Timestamp',
    ]
    'defaultConnection' => 'default'
    'connectionName' => 'default'
  }
}

ROOT\templates\Results\add.php (line 8)
object(Cake\ORM\Query) id:0 {
  '(help)' => 'This is a Query object, to get the results execute or iterate it.'
  'sql' => 'SELECT Worksheets.id AS Worksheets__id FROM worksheets Worksheets LIMIT 200'
  'params' => [
  ]
  'defaultTypes' => [
    'Worksheets__id' => 'integer',
    'Worksheets.id' => 'integer',
    'id' => 'integer',
    'Worksheets__subrank_id' => 'integer',
    'Worksheets.subrank_id' => 'integer',
    'subrank_id' => 'integer',
    'Worksheets__link' => 'string',
    'Worksheets.link' => 'string',
    'link' => 'string',
    'Worksheets__created' => 'date',
    'Worksheets.created' => 'date',
    'created' => 'date',
    'Worksheets__modified' => 'date',
    'Worksheets.modified' => 'date',
    'modified' => 'date',
  ]
  'decorators' => (int) 0
  'executed' => false
  'hydrate' => true
  'buffered' => true
  'formatters' => (int) 1
  'mapReducers' => (int) 0
  'contain' => [
  ]
  'matching' => [
  ]
  'extraOptions' => [
  ]
  'repository' => object(App\Model\Table\WorksheetsTable) id:1 {
    'registryAlias' => 'Worksheets'
    'table' => 'worksheets'
    'alias' => 'Worksheets'
    'entityClass' => 'App\Model\Entity\Worksheet'
    'associations' => [
      (int) 0 => 'Subranks',
      (int) 1 => 'Results',
    ]
    'behaviors' => [
      (int) 0 => 'Timestamp',
    ]
    'defaultConnection' => 'default'
    'connectionName' => 'default'
  }
}