Joining tables CakePHP

Question

I have a table batch_detail_process has foreign key batch_detail_id and it is joined with belongsTo in model. Now I want to get the ArticleRatio on the basis of article_id & item_id.

My tables foreign keys are as follows:

batch_details_processes = id, batch_detail_id

batch_details = id, batch_id, item_id

batch = id, article_id,

article_ratios = id, article_id, item_id,ratio

$conditions = array();

$conditions['joins'] = array(
                array(
                    'table' => 'batches',
                    'alias' => 'Batch',
                    'type' => 'LEFT',
                    'conditions' => array(
                        'Batch.id = BatchDetail.batch_id'
                    )
                ),
                array(
                    'table' => 'article_ratios',
                    'alias' => 'ArticleRatio',
                    'type' => 'LEFT',
                    'conditions' => array(
                        'ArticleRatio.article_id = Batch.article_id',
                        'ArticleRatio.item_id = BatchDetail.item_id'
                    )
                )
            );

        $bdp = $this->BatchDetailsProcess->find('all',$conditions);

pr($bdp);

returns following:

SQL Generated by it:

SELECT  `BatchDetailsProcess`.`id`, `BatchDetailsProcess`.`batch_detail_id`,
        `BatchDetailsProcess`.`qty_in`, `BatchDetailsProcess`.`qty_out`,
        `BatchDetailsProcess`.`process_step_id`, `BatchDetailsProcess`.`qc_test`,
        `BatchDetailsProcess`.`qc_note`, `BatchDetailsProcess`.`qc_accept`,
        `BatchDetailsProcess`.`qc_reject`, `BatchDetailsProcess`.`moved_further`,
        `BatchDetailsProcess`.`assigned_to`, `BatchDetailsProcess`.`receive_confirmation`,
        `BatchDetailsProcess`.`created_by`, `BatchDetailsProcess`.`updated_by`,
        `BatchDetailsProcess`.`created`, `BatchDetailsProcess`.`updated`,
        `BatchDetail`.`id`, `BatchDetail`.`batch_id`, `BatchDetail`.`po_transaction_id`,
        `BatchDetail`.`current_position`, `BatchDetail`.`out_date`,
        `BatchDetail`.`item_id`, `ProcessStep`.`id`, `ProcessStep`.`article_id`,
        `ProcessStep`.`production_step_id`, `ProcessStep`.`sequence`,
        `ProcessStep`.`rate_per`, `ProcessStep`.`amount_per`
    FROM  `star_impact`.`batch_details_processes` AS `BatchDetailsProcess`
    LEFT JOIN  `star_impact`.`batch_details` AS `BatchDetail`
           ON (`BatchDetailsProcess`.`batch_detail_id` = `BatchDetail`.`id`)
    LEFT JOIN  `star_impact`.`process_steps` AS `ProcessStep`
           ON (`BatchDetailsProcess`.`process_step_id` = `ProcessStep`.`id`)
    LEFT JOIN  `star_impact`.`batches` AS `Batch`
           ON (`Batch`.`id` = `BatchDetail`.`batch_id`)
    LEFT JOIN  `star_impact`.`article_ratios` AS `ArticleRatio`
           ON (`ArticleRatio`.`article_id` = `Batch`.`article_id`
              AND  `ArticleRatio`.`item_id` = `BatchDetail`.`item_id`
                          )
    WHERE  1 = 1

I want to select article ratios on basis of matching article_id & item_id. But results doesn't return the ArticleRatio but only BatchDetailProcess, BatchDetail and ProcessStep.

AD7six · Accepted Answer

results doesn't return the ArticleRatio

Joins are not associations.

CakePHP's ORM does not issue SELECT * queries, fields are always specified so from the question:

SELECT 
    ... <- No ArticleRatio here 
FROM 
    `star_impact`.`batch_details_processes` AS `BatchDetailsProcess` 
...
WHERE 
    1 = 1

If there is no mention in select, there will be no fields returned from the joined table, and no data for CakePHP from those tables.

Either:

Specify the fields in the query

Instead of letting CakePHP decide which fields to return, specify them:

$conditions['fields'] = '*';
$bdp = $this->BatchDetailsProcess->find('all',$conditions);

SELECT 
    * <- Lazy, all fields. Or be more specific with 'fields'
FROM 
    `star_impact`.`batch_details_processes` AS `BatchDetailsProcess` 
...
WHERE 
    1 = 1

Note that the second parameter to find is parameters not conditions.

OR:

Use associations.

Instead of joins, use temporary associations:

$this->BatchDetailsProcess->bindModel('hasOne', [
    'Batch' =>  [
        'conditions' => [
            'Batch.id = BatchDetail.batch_id'
        ]
    ],
    'ArticleRatio' => [
        'conditions' => [
            'ArticleRatio.article_id = Batch.article_id',
            'ArticleRatio.item_id = BatchDetail.item_id'
        ]
    ]
]);
$this->BatchDetailsProcess->find();

This will create a left join, and add populate the fields/entities in the response; adapt the parameters passed to the association definitions (and use containable) to suit.

Joining tables CakePHP

Answers (1)

Joins are not associations.

Specify the fields in the query

Use associations.

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