Laravel: Difference between whereHas and with contains constraint-CodePudding

What is difference between:

->whereHas('user', function($user){
    $user->where('age', '>', 21);
})

and

->with(['user' => function($user){
    $user->where('age', '>', 21);
}])

apart from that with method causes eager loading?

CodePudding user response：

As you said, With causes eager loading but doesn't restrict/filter the results.

WhereHas doesn't eager load the user model but restricts/filters the results.

Imagine a Blogs model that can have a user or not.

WhereHas will query for models with a user meeting the requirements and only return models that do.

With will query for all blog models but only include the user when it meets the requirement.

Three blog posts

id: 1
user: { id: 1, age: 25 }
title: blog post 1

id: 2
user: null
title: blog post two without user

id: 3
user: { id: 3, age: 15 }
title: blog post 2 with user low age

This

Blog::whereHas('user', function($user){
    $user->where('age', '>', 21);
})->get()

will return you

id: 1
user: null
user_id: 1
title: blog post 1

While

Blog::with(['user' => function($user){
    $user->where('age', '>', 21);
}])->get()

Will return you

id: 1
user: { id: 1, age: 25 }
user_id: 1
title: blog post 1

id: 2
user: null
user_id: null
title: blog post 2 without user

id: 3
user: null
user_id: 3
title: blog post 2 with user low age

You would most likely be using the two together, like this, restricted to fetch only blog posts by users over the age of 21, and eager load the user model on those, without the restriction since results are already limited for it in the whereHas.

Blog::whereHas('user', function($user){
    $user->where('age', '>', 21);
})->with('user');