$school=$school->teachers->load('TeacherCourses');
This will return all teachers with their courses in my laravel project..
can I use with() function like below?? if I cant then how ?
$school=$school->teachers->with('TeacherCourses');
Yes, but the correct syntax would be different. load() is used after you've retrieved the model from the Database, but with() is used prior to that.
$school = School::first();
$school->teachers->load('teacherCourses');
̶T̶h̶i̶s̶ ̶w̶o̶n̶'̶t̶ ̶w̶o̶r̶k̶,̶ ̶a̶s̶ ̶̶t̶e̶a̶c̶h̶e̶r̶s̶̶ ̶s̶u̶g̶g̶e̶s̶t̶s̶ ̶a̶ ̶C̶o̶l̶l̶e̶c̶t̶i̶o̶n̶,̶ ̶w̶h̶i̶c̶h̶ ̶d̶o̶e̶s̶n̶'̶t̶ ̶h̶a̶v̶e̶ ̶a̶ ̶̶l̶o̶a̶d̶(̶)̶̶ ̶m̶e̶t̶h̶o̶d̶.̶ Corrected by #patricus; Collections do have a load() method, so ->teachers->load('teacherCourses') will work. Alternative syntax would be:
$school->load('teachers.teacherCourses');
The more efficient way to write this is:
$school = School::with('teachers.teacherCourses')->first();
This will eager-load both the teachers and teacherCourses nested relationships, in a minimal number of database calls.
Edit
Route Model Binding will do this behind-the-scenes:
$school = School::findOrFail($schoolId);
Since it's only loading a single Model, using load() is perfectly acceptable. with() loads the relationships via a single query, for a total of 1 + (# of relationships loaded) queries (3 in your case, school, teachers and teacherCourses). load() will do the same thing, so there's no need to use with() over load() in this case.
Related
I really tried to understand the difference between the with() method and the load() method, but couldn't really understand.
As I see it, using the with() method is "better" since I eager load the relation. It seems that if I use load() I load the relation just as if I would use the hasMany() (or any other method that relates to the relation between objects).
Do I get it wrong?
Both accomplish the same end results—eager loading a related model onto the first. In fact, they both run exactly the same two queries. The key difference is that with() eager loads the related model up front, immediately after the initial query (all(), first(), or find(x), for example); when using load(), you run the initial query first, and then eager load the relation at some later point.
"Eager" here means that we're associating all the related models for a particular result set using just one query, as opposed to having to run n queries, where n is the number of items in the initial set.
Eager loading using with()
If we eager load using with(), for example:
$users = User::with('comments')->get();
...if we have 5 users, the following two queries get run immediately:
select * from `users`
select * from `comments` where `comments`.`user_id` in (1, 2, 3, 4, 5)
...and we end up with a collection of models that have the comments attached to the user model, so we can do something like $users->comments->first()->body.
"Lazy" eager loading using load()
Or, we can separate the two queries, first by getting the initial result:
$users = User::all();
which runs:
select * from `users`
And later, if we decide that we need the related comments for all these users, we can eager load them after the fact:
$users = $users->load('comments');
which runs the 2nd query:
select * from `comments` where `comments`.`user_id` in (1, 2, 3, 4, 5)
...and we end up with the same result, just split into two steps. Again, we can call $users->comments->first()->body to get to the related model for any item.
Why use load() vs. with()? load() gives you the option of deciding later, based on some dynamic condition, whether or not you need to run the 2nd query. If, however, there's no question that you'll need to access all the related items, use with().
The alternative to either of these would be looping through the initial result set and querying a hasMany() relation for each item. This would end up running n+1 queries, or 6 in this example. Eager loading, regardless of whether it's done up-front with with() or later with load(), only runs 2 queries.
As #damiani said, Both accomplish the same end results—eager loading a related model onto the first. In fact, they both run exactly the same two queries. The key difference is that with() eager loads the related model up front, immediately after the initial query (all(), first(), or find(x), for example); when using load(), you run the initial query first, and then eager load the relation at some later point.
There is one more difference between With() & load(), you can put the conditions when using with() but you can't do the same in case of load()
For example:
ProductCategory::with('children')
->with(['products' => function ($q) use($SpecificID) {
$q->whereHas('types', function($q) use($SpecificID) {
$q->where('types.id', $SpecificID)
});
}])
->get();
#damiani Explanied difference between load() and with() as well but he said load() is not cacheable so I wanna say couple words about it.
Let assume we have a blog post and related with comments. And we're fetching together and caching it.
$post = Cache::remember("post.".$slug,720,function()use($slug){
return Post::whereSlug($slug)->with("comments")->first();
});
But if there is a new comment and we want to display it immediately, we have to clear post cache and fetch post and comments together again. And that causes unnecessary queries. Lets think there are another queries for tags, media, contributors of the post etc. it will increase amount of resource usage..
public function load($relations)
{
$query = $this->newQueryWithoutRelationships()->with(
is_string($relations) ? func_get_args() : $relations
);
$query->eagerLoadRelations([$this]);
return $this;
}
As you can see above when we use the method it loads given relation and returns model with fetched relation. So you can return it outside of a callback.
$post = Cache::remember("post.".$slug,720,function()use($slug){
return Post::whereSlug($slug)->first();
});
$post = Cache::remember("post.relation.images.".$slug,720,function()use($post){
return $post->load("images");
});
$post = Cache::remember("post.relation.comments".$slug,720,function()use($post){
return $post->load("comments");
});
So if we load them seperatly, next time when some of them updated all you need to do clear specific relation cache and fetch it again. No need to fetch post, tags, images etc. over and over.
So, in order to check the existence of a relationship on a model, we use the has function on the relationship like model1->has('relationship1').
While it is possible to supply the model1->with() function with an array of relations to eager load them all, both has and whereHas functions do not accept arrays as parameters. How to check for the existence of multiple relationships?
Right now, I am running multiple has functions on the same model (The relations are not nested):
model1->has('relationship1')
->has('relationship2')
->has('relationship3')
But that is tedious and error-prone. Solution anyone?
There unfortunately isn't a way to pass an array of relationships to has() or whereHas(), but you can use a QueryScope instead. On your Model, define the following:
public function scopeCheckRelationships($query){
return $query->has("relationship1")->has("relationship2")->has("relationship3");
}
Then, when querying your Model in a Controller, simply run:
$result = Model::checkRelationships()->get();
The function name to use a Scope is the name of the function, minus the word scope, so scopeCheckRelationships() is used as checkRelationships().
Also, it's actually possible to pass the relationships you want to query as a param:
public function scopeCheckRelationships($query, $relationships = []){
foreach($relationships AS $relationship){
$query->has($relationship);
// Might need to be `$query = $query->has(...);`, but I don't think so.
}
return $query;
}
...
$result = Model::checkRelationships(["relationship1", "relationship2", "relationship3"])->get();
In case you need this to be dynamic.
Here's the documentation for Query Scopes if you need more info: https://laravel.com/docs/5.8/eloquent#query-scopes
I created a queryScope
public function scopeCtmpActive($query)
{
return $query->where('ctmp_active', 'y');
}
Then I replace following line
$customtemplates_collection = Auth::user()->customtemplates->where('ctmp_active', 'y')->sortByDesc('ctmp_id');
with
$customtemplates_collection = Auth::user()->customtemplates->ctmpActive()->sortByDesc('ctmp_id');
And I am getting following FatalErrorException
Call to undefined method Illuminate\Database\Eloquent\Collection::ctmpActive()
How am I suppose to use a query exception with a relationship?
As the name implies, "query" scopes are for reusable, common "query" constraints.
$customtemplates_collection = Auth::user()->customtemplates;
This returns a collection. You are getting all "customtemplates" that belong to the authenticated user. Then, Laravel is nice in that the Collection class allows for a nice way to filter out results, which is why the next part works:
$customtemplates_collection = Auth::user()->customtemplates->where('ctmp_active', 'y');
You are using PHP. Not MySQL. To emphasize, you are getting every single "customtemplates" that belongs to the user, and then using (PHP) Laravel Collection's where method to go through each one and filter out the results. You are not adding a where clause to the query. That's why the above works.
However, query scopes are for query constraints so they need to happen during the query, not after. What you probably want is something like this:
$customtemplates_collection = Auth::user()->customtemplates()->ctmpActive()->orderBy('ctmp_id', 'desc')->get();
When you add the paranthesis after customtemplates(), you are invoking the customtemplates method. In this case, I'm assuming it's a HasMany relationship so it'll return a HasMany instance. Then basically, it uses PHP's magic method (__call) to build the query builder so each method after that is essentially prepping the database query. Then, when you're finished building the query, you call get to fetch the results.
In Laravel 4.2 I have a model called Product with many-to-many relationshis to other models like Country or Category. I want to filter out products that are "incomplete", which means they have no connected countries or no connected categories. I can use whereDoesntHave() method to filter out one relation. When I use it two times in one query it creates AND condition, but I need OR. I can't find orWhereDoesntHave() method in API documentation. I can't pass multiple relations as arguments because it expects first argument to be a string.
I need something like this:
$products = Product::whereDoesntHave('categories')->orWhereDoesntHave('countries')->get();
Is there any way to achive whereDoesntHave() with multiple OR conditions?
You can use doesntHave and specify the boolean operator:
$products = Product::doesntHave('categories')->doesntHave('countries', 'or')->get();
Actually you only need whereDoesntHave if you want to pass in a closure to filter the related models before checking if any of them exist. In case you want to do that you can pass the closure as third argument:
$products = Product::doesntHave('categories', 'or', function($q){
$q->where('active', false);
})->doesntHave('countries', 'or')->get();
Since Laravel 5.5 there is an orWhereDoesntHave function.
You may use it like this
Product::whereDoesntHave('categories', function($q){ //... })
->orWhereDoesntHave('countries', function($q){//...})
->get();
From you example it seems that you are not using a where clause, so you may just use
Product::doesntHave('categories')
->orDoesntHave('countries')
->get();
Use
Product::whereDoesntHave('categories')->doesntHave('countries', 'or')->get();
Laravel Source Code:
whereDoesntHave https://github.com/illuminate/database/blob/master/Eloquent/Builder.php#L654
calls
https://github.com/illuminate/database/blob/master/Eloquent/Builder.php#L628
internally.
Let’s say we have Authors and Books, with 1-n relationship – one Author can have one or many Books. Here’s how it looks in app\Author.php:
public function books()
{
return $this->hasMany(\App\Book::class, 'author_id');
}
Now, what if we want to show only those Authors that have at least one book? Simple, there’s method has():
$authors = Author::has('books')->get();
Similarly, there’s an opposite method – what if we want to query only the authors without any books? Use doesnthave():
$authors = Author::doesnthave('books')->get();
It’s not only convenient, but also super-easy to read and understand, even if you’re not a Laravel developer, right?
I really tried to understand the difference between the with() method and the load() method, but couldn't really understand.
As I see it, using the with() method is "better" since I eager load the relation. It seems that if I use load() I load the relation just as if I would use the hasMany() (or any other method that relates to the relation between objects).
Do I get it wrong?
Both accomplish the same end results—eager loading a related model onto the first. In fact, they both run exactly the same two queries. The key difference is that with() eager loads the related model up front, immediately after the initial query (all(), first(), or find(x), for example); when using load(), you run the initial query first, and then eager load the relation at some later point.
"Eager" here means that we're associating all the related models for a particular result set using just one query, as opposed to having to run n queries, where n is the number of items in the initial set.
Eager loading using with()
If we eager load using with(), for example:
$users = User::with('comments')->get();
...if we have 5 users, the following two queries get run immediately:
select * from `users`
select * from `comments` where `comments`.`user_id` in (1, 2, 3, 4, 5)
...and we end up with a collection of models that have the comments attached to the user model, so we can do something like $users->comments->first()->body.
"Lazy" eager loading using load()
Or, we can separate the two queries, first by getting the initial result:
$users = User::all();
which runs:
select * from `users`
And later, if we decide that we need the related comments for all these users, we can eager load them after the fact:
$users = $users->load('comments');
which runs the 2nd query:
select * from `comments` where `comments`.`user_id` in (1, 2, 3, 4, 5)
...and we end up with the same result, just split into two steps. Again, we can call $users->comments->first()->body to get to the related model for any item.
Why use load() vs. with()? load() gives you the option of deciding later, based on some dynamic condition, whether or not you need to run the 2nd query. If, however, there's no question that you'll need to access all the related items, use with().
The alternative to either of these would be looping through the initial result set and querying a hasMany() relation for each item. This would end up running n+1 queries, or 6 in this example. Eager loading, regardless of whether it's done up-front with with() or later with load(), only runs 2 queries.
As #damiani said, Both accomplish the same end results—eager loading a related model onto the first. In fact, they both run exactly the same two queries. The key difference is that with() eager loads the related model up front, immediately after the initial query (all(), first(), or find(x), for example); when using load(), you run the initial query first, and then eager load the relation at some later point.
There is one more difference between With() & load(), you can put the conditions when using with() but you can't do the same in case of load()
For example:
ProductCategory::with('children')
->with(['products' => function ($q) use($SpecificID) {
$q->whereHas('types', function($q) use($SpecificID) {
$q->where('types.id', $SpecificID)
});
}])
->get();
#damiani Explanied difference between load() and with() as well but he said load() is not cacheable so I wanna say couple words about it.
Let assume we have a blog post and related with comments. And we're fetching together and caching it.
$post = Cache::remember("post.".$slug,720,function()use($slug){
return Post::whereSlug($slug)->with("comments")->first();
});
But if there is a new comment and we want to display it immediately, we have to clear post cache and fetch post and comments together again. And that causes unnecessary queries. Lets think there are another queries for tags, media, contributors of the post etc. it will increase amount of resource usage..
public function load($relations)
{
$query = $this->newQueryWithoutRelationships()->with(
is_string($relations) ? func_get_args() : $relations
);
$query->eagerLoadRelations([$this]);
return $this;
}
As you can see above when we use the method it loads given relation and returns model with fetched relation. So you can return it outside of a callback.
$post = Cache::remember("post.".$slug,720,function()use($slug){
return Post::whereSlug($slug)->first();
});
$post = Cache::remember("post.relation.images.".$slug,720,function()use($post){
return $post->load("images");
});
$post = Cache::remember("post.relation.comments".$slug,720,function()use($post){
return $post->load("comments");
});
So if we load them seperatly, next time when some of them updated all you need to do clear specific relation cache and fetch it again. No need to fetch post, tags, images etc. over and over.