CODEWITHSUNDEEP
phplaraveleloquentlaravel-collection
Martyn
Martyn

Reputation: 6383

How to Merge Two Eloquent Collections?

I have a questions table and a tags table. I want to fetch all questions from tags of a given question. So, for example, I may have the tags "Travel," "Trains" and "Culture" attached to a given question. I want to be able to fetch all questions for those three tags. The tricky, so it seems, is that questions and tags relationship is a many-to-many defined in Eloquent as belongsToMany.

I thought about trying to merge the questions Collections as below:

foreach ($question->tags as $tag) {
    if (!isset($related)) {
        $related = $tag->questions;
    } else {
        $related->merge($tag->questions);
    }
}

It doesn't seem to work though. Doesn't seem to merge anything. Am I attempting this correctly? Also, is there perhaps a better way to fetch a row of rows in a many-to-many relationship in Eloquent?

Upvotes: 145

Views: 291149

Answers (9)

trckster
trckster

Reputation: 610

I'm sorry about that, but since PHP 7.4 you're available to do like this (better use merge).

$foo = Foo::all();
$bar = Bar::all();

/** $foo will contain $foo + $bar */
$foo->push(...$bar);

Upvotes: -1

Miraj Khandaker
Miraj Khandaker

Reputation: 1082

I have faced some issue by using merge. So I used concat. You can used it like below.

$users = User::all();
$associates = Associate::all();
$userAndAssociate = $users->concat($associates);

Upvotes: 9

AidenFry
AidenFry

Reputation: 278

I would like to add that, i found that the concat method does not seem to override based on ID, while the merge method does. concat seems to work for me, while merge caused issues.

Upvotes: 0

João Carlos Junior
João Carlos Junior

Reputation: 301

Creating a new base collection for each eloquent collection the merge works for me.

$foo = collect(Foo::all());
$bar = collect(Bar::all());
$merged = $foo->merge($bar);

In this case don't have conflits by its primary keys.

Upvotes: 19

Luke Snowden
Luke Snowden

Reputation: 4196

All do not work for me on eloquent collections, laravel eloquent collections use the key from the items I think which causes merging issues, you need to get the first collection back as an array, put that into a fresh collection and then push the others into the new collection;

public function getFixturesAttribute()
{
    $fixtures = collect( $this->homeFixtures->all() );
    $this->awayFixtures->each( function( $fixture ) use ( $fixtures ) {
        $fixtures->push( $fixture );
    });
    return $fixtures;
}

Upvotes: 2

sh6210
sh6210

Reputation: 4540

$users = User::all();
$associates = Associate::all();

$userAndAssociate = $users->merge($associates);

Upvotes: 35

newbie2005
newbie2005

Reputation: 209

Merge two different eloquent collections into one and some objects happen to have the same id, one will overwrite the other. Use push() method instead or rethink your approach to the problem to avoid that. Refer to web

Upvotes: 20

patricus
patricus

Reputation: 62238

The merge() method on the Collection does not modify the collection on which it was called. It returns a new collection with the new data merged in. You would need:

$related = $related->merge($tag->questions);

However, I think you're tackling the problem from the wrong angle.

Since you're looking for questions that meet a certain criteria, it would probably be easier to query in that manner. The has() and whereHas() methods are used to generate a query based on the existence of a related record.

If you were just looking for questions that have any tag, you would use the has() method. Since you're looking for questions with a specific tag, you would use the whereHas() to add the condition.

So, if you want all the questions that have at least one tag with either 'Travel', 'Trains', or 'Culture', your query would look like:

$questions = Question::whereHas('tags', function($q) {
    $q->whereIn('name', ['Travel', 'Trains', 'Culture']);
})->get();

If you wanted all questions that had all three of those tags, your query would look like:

$questions = Question::whereHas('tags', function($q) {
    $q->where('name', 'Travel');
})->whereHas('tags', function($q) {
    $q->where('name', 'Trains');
})->whereHas('tags', function($q) {
    $q->where('name', 'Culture');
})->get();

Upvotes: 51

Wader
Wader

Reputation: 9883

The merge method returns the merged collection, it doesn't mutate the original collection, thus you need to do the following

$original = new Collection(['foo']);

$latest = new Collection(['bar']);

$merged = $original->merge($latest); // Contains foo and bar.

Applying the example to your code

$related = new Collection();

foreach ($question->tags as $tag)
{
    $related = $related->merge($tag->questions);
}

Upvotes: 215

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