Laravel attach pivot to table with multiple values - laravel

Question

Background
I'm creating a database revolving around food allergies and I have a many to many relationship between foods and allergies. There is also a pivot value called severity which has a numerical number representing the severity of the allergy for that food item.
This link table looks like this;
food_id|allergy_id|severity
-------|----------|--------
1 | 1 | 3
1 | 4 | 1
2 | 2 | 1
The problem
When trying to update the link table with Eloquent (where $allergy_ids is an array)
$food->allergies()->attach($allergy_ids);
How would I go about adding multiple values to this pivot table at once along with the pivot values?
I can add all the allergy_id's for a particular food item in one go using the above line, but how can I also add in the severity column at the same time with an array of various severity values? Maybe something like
$food->allergies()->attach($allergy_ids, $severity_ids);
Edit: There could be between 0-20 allergies for a specific food item, and a severity rating from 0-4 for each allergy, if this helps at all.

Answer 1

You can.
From this example in Docs (4.2, 5.0):
$user->roles()->sync(array(1 => array('expires' => true)));
Hardcoded version for the first two rows:
$food = Food::find(1);
$food->allergies()->sync([1 => ['severity' => 3], 4 => ['severity' => 1]]);
Dynamically, with your arrays $allergy_ids and $severities in a compatible state (size and sort), you shall prepare your sync data before. Something like:
$sync_data = [];
for($i = 0; $i < count($allergy_ids); $i++))
$sync_data[$allergy_ids[$i]] = ['severity' => $severities[$i]];
$food->allergies()->sync($sync_data);

Answer 2

You can't do it like you' like so I suggest a simple loop:
foreach ($allergy_ids as $key => $id)
{
$food->allergies()->attach($id, array_get($severity_ids, $key));
// should you need a sensible default pass it as a 3rd parameter to the array_get()
}
workaround
However if you wanted to attach multiple allergies with single severity level/id then you could do this:
$food->allergies()->attach($allergy_ids, array('severity' => $singleSeverityValue));

Answer 3

From version 5.1 of Laravel (Currently in Laravel 9.x) onwards it is possible to pass an array as a second argument with all the additional parameters that need to be saved in the intermediate table.
As you can read in the documentation
When attaching a relationship to a model, you may also pass an array of additional data to be inserted into the intermediate table:
$user->roles()->attach($roleId, ['expires' => $expires]);
For convenience, attach and detach also accept arrays of IDs as input:
$user->roles()->attach([1 => ['expires' => $expires], 2, 3]);
Then you can simply do
$food->allergies()->attach([1 => ['severity' => 3], 4 => ['severity' => 1]]);

Answer 4

So, on Laravel 9, passing the ids in the array worked for me. Likeso,
$user->roles()->attach([$a->id,$b->id,$c->id]); and so on.
I guess instead of passing the string. We can pass just the id or else convert the string into array.

Answer 5

Easiest indeed is to attach with the extra data, like so:
$retailer->paymentmethods()->attach($paymentmethod, array('currency' => $paymentmethod->currency));
change out the values for food allergy severity, but you get the hint... :-)