Combining query results in laravel

Question

On my website, users can upload images and attach tags to those images.

I've got an images table,a tag table and an images_tag pivot table.

Images can have many tags, and tags can belong to many images.

I want to be able to generate a list of all the tags a user has used in his/her images.

$imageIDs = Images::where('created_by', Auth::user()->id)->lists('id');

So this would create a list of all the image IDs that a user has upload.

What I want is essentially "foreach $imageIDs, check the images_tag table and for every match go to the tags table and get me back the tagname value."

But I have no idea how I'd do that.

Maybe a foreach then use the merge method on all the results? Any help would be appreciated!

Alexey Mezenin · Accepted Answer · 2017-01-15 05:26:06Z

1

You need to use whereHas() to check the relationship:

$userTags = Tags::whereHas('images', function($q) {
    $q->where('created_by', auth()->user()->id);
})->get();

Then just pass this data to a view:

return view('some.view', compact('userTags'));

And iterate over tags in a view:

@foreach ($userTags as $tag)
    {{ $tag->name }}
@endforeach

answered Jan 15, 2017 at 5:26

Alexey Mezenin

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Comments

Gayan · Accepted Answer · 2017-01-15 05:05:25Z

1

What you could do is this.

class Tag extends Model
{
    public function images()
    {
        return $this->belongsToMany(Image::class);
    }
}

class SomeController
{
    public function someMethod()
    {
        $tags = Tag::with(['images' => function ($image) {
            return $image->where('created_by', Auth::user()->id);
        }])->select('id', 'tagname')->get();
        // these are your $tags 
    }
}

You should not use a query inside foreach(). Then it would result N+1 problem. What you instead do is eager loading using with() statement.

edited Jan 15, 2017 at 5:05

answered Jan 15, 2017 at 4:38

Gayan

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4 Comments

Gayan Over a year ago

You're getting a collection. $tag collection contains all the tags matches your query. laravel.com/docs/5.3/collections

Felix Over a year ago

Fair enough. So I already had the first functions, images(), in my Tag model doing the whole belongsToMany thing. However, I'm not sure how someMethod would work. I'm still fairly new to Laravel. How would I call this function in my controller so that I could return the view with $tags?

Gayan Over a year ago

Please consider SomeController and someMethod() a dummy Class and a Method since I don't know your code structure. You only gonna need the query part.

Gayan Over a year ago

@FelixMaxime since you mentioned you are fairly new I suggest you watching laracasts.com/series/laravel-5-fundamentals

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