A result set from a PDO query is as follows...

Array
(
[0] => Array
    (
        [activity_link_type] => Category
        [data_id] => 1
    )

[1] => Array
    (
        [activity_link_type] => Category
        [data_id] => 38
    )

[2] => Array
    (
        [activity_link_type] => PData
        [data_id] => 108
    )

[3] => Array
    (
        [activity_link_type] => PData
        [data_id] => 109
    )

[4] => Array
    (
        [activity_link_type] => PData
        [data_id] => 112
    )

[5] => Array
    (
        [activity_link_type] => PData
        [data_id] => 115
    )

[6] => Array
    (
        [activity_link_type] => Role
        [data_id] => 6
    )
)

I wish to 'dedupe' the array in the simplest means (without having to do multiple nested database queries) so it looks like the following...

Array
(
[0] => Array
    (
        [activity_link_type] => Category
        [data_id] => 1
        [data_id] => 38
    )

[1] => Array
    (
        [activity_link_type] => PData
        [data_id] => 108
        [data_id] => 109
        [data_id] => 112
        [data_id] => 115
   
[2] => Array
    (
        [activity_link_type] => Role
        [data_id] => 6
    )
)

I've tried array_merge(), array_merge_recursiveand array_unique() but they either don't do anything or dedupe the wrong level of the array!

All help appreciated!

CodePudding user response：

The array you think you wanted is not possible but how about this, its fairly close and also produces an array with the activity_link_type as a key which may in fact be useful later when trying to access this array

$from_db = [
            ['activity_link_type' => 'Category', 'data_id' => 1 ],
            ['activity_link_type' => 'Category', 'data_id' => 38 ],
            ['activity_link_type' => 'PData', 'data_id' => 108 ],
            ['activity_link_type' => 'PData', 'data_id' => 112 ],
            ['activity_link_type' => 'PData', 'data_id' => 115 ],
            ['activity_link_type' => 'Role', 'data_id' => 6 ]
];

$new = [];

foreach ( $from_db as $a){
    if ( isset( $new[$a['activity_link_type']] ) ) {
        $new[$a['activity_link_type']]['data_ids'][] = $a['data_id'];
    } else {
        $new[$a['activity_link_type']] = ['activity_link_type' => $a['activity_link_type'], 
                                          'data_ids' => [$a['data_id']] ];
    }   
}
print_r($new);

RESULT

Array
(
    [Category] => Array
        (
            [activity_link_type] => Category
            [data_ids] => Array
                (
                    [0] => 1
                    [1] => 38
                )
        )
    [PData] => Array
        (
            [activity_link_type] => PData
            [data_ids] => Array
                (
                    [0] => 108
                    [1] => 112
                    [2] => 115
                )
        )
    [Role] => Array
        (
            [activity_link_type] => Role
            [data_ids] => Array
                (
                    [0] => 6
                )
        )
)