在 CakePHP 3 中检索相关数据 (hasMany)

Retrieve related data (hasMany) in CakePHP 3 

Events hasMany TicketTypes
TicketTypes belogsTo Events

我正在尝试检索具有关联票证类型的所有事件：

$query= $this->Events
    ->find()
    ->select(['id', 'name'])
    ->autoFields(false)
    ->contain(['TicketTypes' => function($q) { 
        return $q->select(['TicketTypes.id', 'TicketTypes.name']); }])
;

SQL 查询生成：

SELECT Events.id AS `Events__id`, Events.name AS `Events__name` FROM events Events

但我期望的是：

SELECT Events.id AS `Events__id`, Events.name AS `Events__name`, TicketTypes.id AS `TicketTypes__id`, TicketTypes.name AS `TicketTypes__name` FROM events Events LEFT JOIN ticket_types TicketTypes ON Events.id = (TicketTypes.event_id)

我的模型是这样配置的：

class EventsTable extends Table
{
    public function initialize(array $config)
    {
        $this->displayField('name');

        $this->addAssociations([
            'hasMany'=> ['TicketTypes']
        ]);
    }
}

class TicketTypesTable extends Table
{
    public function initialize(array $config)
    {
        $this->displayField('name');

        $this->addAssociations([
            'belongsTo' => ['Events']
        ]); 
    }
}

这是调试查找查询的结果：

object(Cake\ORM\Query) {

    '(help)' => 'This is a Query object, to get the results execute or iterate it.',
    'sql' => 'SELECT Events.id AS `Events__id`, Events.name AS `Events__name` FROM events Events',
    'params' => [],
    'defaultTypes' => [
        'Events.id' => 'integer',
        'id' => 'integer',
        'Events.name' => 'string',
        'name' => 'string',
        'Events.datetime_start' => 'datetime',
        'datetime_start' => 'datetime',
        'Events.datetime_end' => 'datetime',
        'datetime_end' => 'datetime',
        'Events.created' => 'datetime',
        'created' => 'datetime',
        'Events.modified' => 'datetime',
        'modified' => 'datetime',
        'Events.slug' => 'string',
        'slug' => 'string',
        'TicketTypes.id' => 'integer',
        'TicketTypes.event_id' => 'integer',
        'event_id' => 'integer',
        'TicketTypes.name' => 'string',
        'TicketTypes.description' => 'text'
    ],
    'decorators' => (int) 0,
    'executed' => false,
    'hydrate' => true,
    'buffered' => true,
    'formatters' => (int) 0,
    'mapReducers' => (int) 0,
    'contain' => [
        'TicketTypes' => [
            'queryBuilder' => object(Closure) {

            }
        ]
    ],
    'matching' => [],
    'extraOptions' => [],
    'repository' => object(App\Model\Table\EventsTable) {

        'registryAlias' => 'Events',
        'table' => 'events',
        'alias' => 'Events',
        'entityClass' => 'App\Model\Entity\Event',
        'associations' => [
            (int) 0 => 'tickettypes'
        ],
        'behaviors' => [],
        'defaultConnection' => 'default',
        'connectionName' => 'default'

    }

}

这是调试的结果 $query->all():

object(Cake\ORM\ResultSet) {

    'items' => [
        (int) 0 => object(App\Model\Entity\Event) {

            'id' => (int) 101,
            'name' => 'qwertyuiop',
            'ticket_types' => [],
            '[new]' => false,
            '[accessible]' => [
                '*' => true
            ],
            '[dirty]' => [],
            '[original]' => [],
            '[virtual]' => [],
            '[errors]' => [],
            '[repository]' => 'Events'

        },
    ...

如您在此行中所见，'ticket_types' => [] 查询未返回票证类型。

我怎样才能检索 TicketTypes 数据？

谢谢。

hasMany 正在单独查询中检索关联

您关于 CakePHP ORM 如何检索关联数据的假设不正确。

与在主查询中使用联接的 hasOne 和 belongsTo 关联不同，hasMany 和 belongsToMany 关联数据是在单独的查询中检索的，即使用从主查询收集的外键值进行过滤，在您的情况下将是 Events.id 列值。

查看 SQL 日志的其余部分，您应该会找到类似于

的查询 
SELECT
    TicketTypes.id AS `TicketTypes__id`, ...
FROM
    ticket_types TicketTypes
WHERE
    TicketTypes.event_id IN (1,2,3, ...)

该查询的结果与主要结果拼接在一起，并在单个结果集中返回。

需要选择外键

第二个问题是您的包含 select() 调用缺少外键列 (TicketTypes.event_id)，这是必需的，因为没有它，ORM 无法将结果拼接在一起，因此门票类型将不会出现在结果中。

引自文档：

When you limit the fields that are fetched from an association, you must ensure that the foreign key columns are selected. Failing to select foreign key fields will cause associated data to not be present in the final result.

另见