My concern is that while orderBy is applied to the query, I'm not sure how the sortBy is applied?
The reason for using sortBy in my case is because I get the collection via the model (i.e. $user->houses->sortBy('created_at')).
I'm just concerned about the performance: is sortBy simply looping each object and sorting them?, or is Laravel smart enough to simply transform the sortBy into an orderBy executed within the original query?
You need orderBy in order to perform a SQL order.
$user->houses()->orderBy('created_at')->get()
You can also eager load the houses in the right order to avoid N+1 queries.
$users = User::with(['houses' => function ($query) {
return $query->orderBy('created_at');
}])->get();
$orderedHouses = $users->first()->houses;
The sortBy method is applied to the Collection so indeed, it will looping each objects.
The orderBy() method is much more efficient than the sortBy() method when querying databases of a non-trivial size / at least 1000+ rows. This is because the orderBy() method is essentially planning out an SQL query that has not yet run whereas the sortBy() method will sort the result of a query.
For reference, it is important to understand the difference between a Collection object and a Builder object in Laravel.
A builder object is, essentially, an SQL query that has not been run. In contrast, a collection is essentially an array with some extra functionality/methods added. Sorting an array is much less efficient than pulling the data from the DB in the correct format on the actual query.
example code :
<?php
// Plan out a query to retrieve the posts alphabetized Z-A
// This is still a query and has not actually run
$posts = Posts::select('id', 'created_at', 'title')->orderBy('title', 'desc');
// Now the query has actually run. $posts is now a collection.
$posts = $posts->get();
// If you want to then sort this collection object to be ordered by the created_at
timestamp, you *could* do this.
// This will run quickly with a small number or rows in the result,
// but will be essentially unusable/so slow that your server will throw 500 errors
// if the collection contains hundreds or thousands or objects.
$posts = $posts->sortBy('created_at');
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.
I'm a bit new to this, and was originally trying to check if my model was returning results with isEmpty(), but thought I'd try count() instead, then I came across the following:
I've got the following code, which returns data from my model:
$results = Game::where('code', '=', $code)->with('genre', 'creator')
And whether I use first() or get() combined with count(result) or $results->count() I get different values, and I'm not sure why.
when using ->first()
dd($results->count()) = 11930 // Number of rows in the db
when using ->get()
dd($results->count()) = 1 // What I'd expect the query to return
when using ->first()
dd(count($results)) = "count(): Parameter must be an array or an object that implements Countable"
when using ->get()
dd(count($results)) = 1
I don't understand 1) why when using first, the count is the same as every row in the db. 2) Why count() can't be used with first().
Is anyone able to shed some light as to why I can't use count on first as I'd like to?
Update:
I'm also not able to use ->isEmpty() with ->first() but can with ->get()...?
When I try using it with first, I get Illuminate\Database\Query\Builder::isEmpty does not exist.
Disclaimer: I'm not sure why your database count and your results count aren't the same, however I can shed some light on the different types of count.
Game::where('code', '=', $code)->count();
This is being called on a query builder instance. It is run on the database query, without selecting all the rows. Check out the title Aggregates here: https://laravel.com/docs/5.7/queries
Game::where('code', '=', $code)->get()->count();
As soon as your use get() laravel selects the rows, boots them all as models, and creates a collection. This count is on the collection (a bit like an array) so just gets the number that are returned (i.e. if they are paginated or anything like that it will just get that amount). Check out Count here.
Game::where('code', '=', $code)->first()->count();
This is being run on the first returned model... unless you've written it, a default laravel model won't have a count() method.
count($results)
Finally, count() when not a class method is just the default php function that returns the length of an array or other object (documentation).
First of all,
get() returns collection of objects while first() returns modal object of query.
$results = Game::where('code', '=', $code)->with('genre', 'creator')
dd($results->count()) = 11930 // Number of rows in the db
when using ->get()
$results = Game::where('code', '=', $code)->with('genre', 'creator')->get()
dd($results->count()) = 1
because it has collection, which contains numbers of objects of database data. As ->count getting only one collection so it returns 1.
I may be missing something extremely trivial, but is it possible to retrieve specific columns/fields from models when grabbing a collection rather then returning the entire item's fields?
Here is my query:
$items = Items::where('visible', true)->take(10)->get();
This obviously returns each item in there entirety, including unique id's, and other fields i dont want to be fetched... how can i refine this query to just select specific fields from the models?
Laravel Query Builder get() function receives array of columns which you need to fetch.
$items = Items::where('visible', true)->take(10)->get(['column_1', 'column_2']);
Use select() method to do this:
$items = Items::select(['column_1', 'column_2']'])->where('visible', true)->take(10)->get();
Source: Latavel Database Query Builder
Laravel Query Builder gives a huge flexibility to write this types of query.
You can use select(), get(), all() methods.
Items::where('visible', true)->take(10)->get('col_1', 'col_2');
OR
Items::select('col_1', 'col_2')->where('visible', true)->take(10)->get();
Items::select(['col_1', 'col_2'])->where('visible', true)->take(10)->get();
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 $post->load("comments");
});
So if we load them seperatly, next time when some of them updated all you need to do clear specific relation cache and fetch it again. No need to fetch post, tags, images etc. over and over.
I am new to laravel and confused about some query methods.
find($id) is useful and returns a nice array, but sometimes I need to select by other fields rather than id.
The Laravel document said I could use where('field', '=', 'value') and return a bunch of data, which is fine.
What I can't understand is why I need to add ->first() every time, even if I am pretty sure there is only one single row matches the query.
It goes like this:
$query->where(..)->orderBy(..)->limit(..) etc.
// you can chain the methods as you like, and finally you need one of:
->get($columns); // returns Eloquent Collection of Models or array of stdObjects
->first($columns); // returns single row (Eloquent Model or stdClass)
->find($id); // returns single row (Eloquent Model or stdClass)
->find($ids); // returns Eloquent Collection
// those are examples, there are many more like firstOrFail, findMany etc, check the api
$columns is an array of fields to retrieve, default array('*')
$id is a single primary key value
$ids is an array of PKs, this works in find method only for Eloquent Builder
// or aggregate functions:
->count()
->avg()
->aggregate()
// just examples here too
So the method depends on what you want to retrieve (array/collection or single object)
Also the return objects depend on the builder you are using (Eloquent Builder or Query Builder):
User::get(); // Eloquent Colleciton
DB::table('users')->get(); // array of stdObjects
even if I am pretty sure there is only one single row matches the query.
Well Laravel cant read your mind - so you need to tell it what you want to do.
You can do either
User::where('field', '=', 'value')->get()
Which will return all objects that match that search. Sometimes it might be one, but sometimes it might be 2 or 3...
If you are sure there is only one (or you only want the first) you can do
User::where('field', '=', 'value')->first()
get() returns an array of objects (multiple rows)
while
first() returns a single object (a row)
You can of course use get() when you know it will return only one row, but you need to keep that in mind when addressing the result:
using get()
$rez = \DB::table('table')->where('sec_id','=','5')->get();
//will return one row in an array with one item, but will be addressed as:
$myfieldvalue = $rez[0]->fieldname;
using first()
$rez = \DB::table('table')->where('sec_id','=','5')->first();
// will also return one row but without the array, so
$myfieldvalue = $rez->fieldname;
So it depends on how you want to access the result of the query: as an object or as an array, and also depends on what "you know" the query will return.
first() is the equivalent of LIMIT 1 at the end of your SELECT statement. Even if your query would return multiple rows, if you use first() it will only return the first row