Counting a Model Relations in Laravel

Everywhere I go in Laravel, I find treasures in the Docs! Ofcourse it's not a treasure if it's easily findable but I don't know what to call something precious and usefull other than treasure, lol. One treasure I found is "models' relations count"! Let's jump into it.

Study Case

Let's pretend we have a model and what's better than using User.php as our example model! The User is usually tied to many other models in an app and they all can be related in different ways. Some of them are one-to-many while others are one-to-one. Sometimes we might have morph relations like a Post. Posts can be written be Users or Teams.

Scenario

In our Scenario, the users are really rich and they have multiple cars and houses. They also have stocks to many companies and tags for the types of companies they have stocks.

Issue

We need to create a report for all the users and how relations do they have such as cars, houses, tags, stocks, etc.

Normal Solution

As a typical solution, we'll query all the users and all their relations eagrly.

$users = User::with(['cars','boats','houses',tags','stocks'])->get();

foreach($users as $user){
  echo $user->cars->count();
  echo $user->boats->count();
  ...
}

But if we're only querying the relations to get their counts only. Why do we even need to query the relations?! Actually, Laravel provides a way to only query the count of the relations which is more convient and effecient. How can we do that?

Better Solution

We can do it by using the withCount() method on the model itself.

$users = User::withCount(['cars','boats','houses',tags','stocks'])->get();

// Notice that laravel will automatically add *_count to the relation
// and put it as a property

foreach($users as $user){
  echo $user->cars_count;
  echo $user->boats_count;
  ...
}

More Details

Let's say we already have the model queried but we need to add the count to a relation at one point. Here, we use the loadCount() function.

public function addUserStuff(User $user){
  $user = $user->loadCount('stocks');

  echo $user->stocks_count;
}

Other Agregate Functions

Other than withCount, Laravel provides withMin,withMax,withAvg,withSum,and withExists methods. The method will add a relation_function_column attribte to the current model.

$candidates = User::withSum('region','votes')->get();
foreach($candidates as $candidate){
  echo $candidate->region_sum_votes;
}

and voila! Happy coding!

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