jcord's avatar
Level 4

Grouping Relations in a Collection

Hi,

Not sure whats going on here.

I am attempting to tidy some legacy data in a system. There are duplicate records i want to find, iterate through and remove.

As you can probably see from the code below i want to group on a relation "mixData" and its "stage" field to find duplicates. I get the results i require when adding a new property to the object as "mixDataGroupedByStage" but if i try to overwrite the "mixData" field nothing changes.

What am i doing wrong?

$mixCycles = MixCycle::with(["mixData"])
  ->where("id", 134)
  ->get();

$mixCycles->map(function ($mixCycle) {
  $mixCycle->mixDataGroupedByStage = $mixCycle->mixData->groupBy("stage");
  $mixCycle->mixData = $mixCycle->mixData->groupBy("stage");
  return $mixCycle;
});

the results

to save on showing all data, the MixData model contains a "stage" field

Any pointers greatly appreciated

0 likes
2 replies
LaryAI's avatar
Level 58

The issue you're encountering is due to the fact that the mixData relationship is an Eloquent collection, and when you attempt to overwrite it with a grouped collection, it doesn't persist the changes as expected. This is because Eloquent collections are designed to represent the relationship data as it is retrieved from the database, and modifying them directly can lead to unexpected behavior.

To achieve your goal of grouping the mixData by the stage field and effectively replacing the mixData with this grouped data, you can follow these steps:

  1. Create a new property to store the grouped data, as you have done with mixDataGroupedByStage.
  2. Use the new property for any operations that require the grouped data.

Here's how you can modify your code to achieve this:

$mixCycles = MixCycle::with(['mixData'])
    ->where('id', 134)
    ->get();

$mixCycles->map(function ($mixCycle) {
    // Group the mixData by the 'stage' field
    $groupedMixData = $mixCycle->mixData->groupBy('stage');
    
    // Store the grouped data in a new property
    $mixCycle->mixDataGroupedByStage = $groupedMixData;
    
    // If you need to work with the grouped data, use the new property
    // For example, you can iterate over the grouped data like this:
    foreach ($mixCycle->mixDataGroupedByStage as $stage => $data) {
        // Perform operations on each group
    }
    
    return $mixCycle;
});

By using a separate property (mixDataGroupedByStage), you can work with the grouped data without affecting the original mixData relationship. This approach ensures that you maintain the integrity of the Eloquent model and its relationships while still achieving the desired grouping functionality.

1 like
tisuchi's avatar

@jcord How about this?


$mixCycles = MixCycle::with(['mixData'])
    ->where('id', 134)
    ->get();

$mixCycles->map(function ($mixCycle) {
    $mixCycle->setRelation('mixData', $mixCycle->mixData->groupBy('stage'));
    return $mixCycle;
});

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