在CakePHP 3中检索相关数据（hasMany）

Posted 2021-03-29

Events hasMany TicketTypes
TicketTypes belogsTo Events

我正在尝试检索具有相关故障单类型的所有事件：

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

生成的SQL查询：

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

但我的期望是：

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)

这就是我的模型的配置方式：

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']
        ]); 
    }
}

以下是调试查询查询的结果：

object(CakeORMQuery) {

    '(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(AppModelTableEventsTable) {

        'registryAlias' => 'Events',
        'table' => 'events',
        'alias' => 'Events',
        'entityClass' => 'AppModelEntityEvent',
        'associations' => [
            (int) 0 => 'tickettypes'
        ],
        'behaviors' => [],
        'defaultConnection' => 'default',
        'connectionName' => 'default'

    }

}

这是调试$query->all()的结果：

object(CakeORMResultSet) {

    'items' => [
        (int) 0 => object(AppModelEntityEvent) {

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

        },
    ...

正如您在此行中所看到的那样，查询不会返回'ticket_types' => []票证类型。

我该怎么做才能检索TicketTypes数据？

谢谢。

答案

hasMany关联正在单独的查询中检索

关于Cakephp ORM如何检索关联数据的假设是不正确的。

与在主查询中使用连接的hasOne和belongsTo关联不同，hasMany和belongsToMany关联数据在单独的查询中被检索，该查询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，您应该找到类似的查询

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

该查询的结果与主结果一起拼接，并在单个结果集中返回。

需要选择外键

第二个问题是你的包含select()调用缺少外键列（TicketTypes.event_id），这是必需的，因为没有它，ORM不能将结果拼接在一起，因此票证类型将不会出现在结果中。

从文档引用：

限制从关联中提取的字段时，必须确保选择了外键列。未能选择外键字段将导致相关数据不存在于最终结果中。

也可以看看

• Cookbook > Database Access & ORM > Retrieving Associated Data
• Cookbook > Database Access & ORM > Query Builder > Passing Conditions to Contain