I'm currently working on a simple Laravel project where I need to get the posts of the users I'm following. With the code below, I can get the posts but I also add a lot of duplicate queries and an N+1 issue on the Authenticated user. So it's becoming sort of a head scratcher. I've looked though other similar scenarios online but I haven't been able to pinpoint what I'm doing wrong. Perhaps there is a better way. Currently, I have on the User model:
public function usersImFollowing()
{
return $this->belongsToMany(User::class, 'follow_user', 'user_id', 'following_id')
->withPivot('is_following', 'is_blocked')
->wherePivot('is_following', true)
->wherePivot('is_blocked', false)
->paginate(3);
}
public function userPosts()
{
return $this->hasMany(Post::class, 'postable_id', 'id')
->where('postable_type', User::class);
}
As you can see, I am using two booleans to determine if a user is following or is blocked. Also, the Post model is a polymorphic model. There are several things I've tried, among them, I tried a hasManyThrough, without using the hasMany Posts relationship above. It got the posts for each user but since I'm using the booleans above, I couldn't use them in the hasManyThrough, it simply got the posts based on the following_id, whether or not the user was following or was blocked became irrelevant.
Then in a separate service class, I tried the methods below (I'm using a separate class to maintain the code easier). They both get the posts for each user but add an N+1 problem and 12 duplicate queries based on 5 posts from 2 users. I will also need to filter the results based on some conditions, so it will probably add more queries. Additionally, I'm using a Laravel resource collection that would pull other items for each post, such as images, comments, etc., so the amount of queries would increase even more. Not sure, perhaps I'm doing too much and there is an easier way:
Either:
$following = $request->user()->usersImFollowing();
$posts = $following->map(function($user){
return $user->userPosts()->get();
})->flatten(1);
return $posts;
Or
$postsfromfollowing = [];
$following = $request->user()->usersImFollowing()->each(function($user) use (&$postsfromfollowing){
array_push($postsfromfollowing,$user->userPosts);
});
$posts = Arr::flatten($postsfromfollowing);
return $posts;
Maybe you could use scopes to do little celanup of code and generated sql.
In User model something like
public function scopeIsFollowedBy(Builder $query, int $followerId) {
return $query->where('following_id', '=', $followerId);
}
And in Post model
public function scopeIsFollowedBy(Builder $query, int $followerId) {
return $query->whereHas('user', function($q) use ($followerId) {
$q->isFollowedBy($followerId);
});
}
You can use it then in coltroller like any other condition like this:
Post::isFollowedBy($followerId)->...otherConditions...->get();
The SQL generated won't go through foreach but only add one IF EXISTS select (generated by whereHas part of the code)
More on local scopes in Laravel is here https://laravel.com/docs/8.x/eloquent#local-scopes
Related
UserModel has many lead and each lead can have one propertyLead and each propertyLead can have many attachments.
Each model is listed below,
UserModel:
public function leads()
{
return $this->hasMany('App\Models\Leads', 'fk_user_id');
}
LeadsModel:
public function propertyLead()
{
return $this->hasOne('App\Models\PropertyLead', 'fk_lead_id');
}
PropertyLeadModel:
public function attachments()
{
return $this->hasMany('App\Models\Attachments', 'fk_property_lead_id');
}
Now, I am using the Lazy Eager Loading of laravel to readData from dataBase, so far I am able to reach to PropertyLeadModel but I am not able to understand how to reach to attachment relation in the PropertyLeadModel,
$leads = User::find(Auth::user()->id)->leads->load('propertyLead');
so user gives me leads and leads gives me propertyLead but not able to understand how to reach more down to Attachments in the propertyLeadModel.
Please, help me to understand.
Thank you.
You can load nested relationships using "dot" notation.
$user = Auth::user();
$user->load('leads.propertyLead.attachments');
// see all relationships loaded
dd($user);
Since leads and attachments are "many" relationships, they will be Collections you have to iterate through to access any particular instance.
Try this, not tested
$leads = Auth::user()->leads->load('propertyLead', 'propertyLead.attachments');
Try this
User::with('leads.propertyLead.attachments')->where('id',Auth::user()->id)->first();
I have various parent/child relationships, drilling down a few levels. What I want to know is if its possible to do something like this:
$student = Student::find(1);
$student->bursaries()->enrolments()->courses()->where('course','LIKE','%B%');
(With the end goal of selecting the course which is like '%B%'), or if I would have to instead use the DB Query builder with joins?
Models / Relationships
Student:
public function bursaries() {
return $this->hasMany('App\StudentBursary');
}
StudentBursary:
public function enrolments() {
return $this->hasMany('App\StudentBursaryEnrolment');
}
If what you want is to query all courses, from all enrollments, from all bursaries, from a students, then, unfortunately, you are one table too many from getting by with the Has Many Through relationship, because it supports only 3 tables.
Online, you'll find packages that you can import / or answers that you can follow to provide you more though of solutions, for example:
1) How to use Laravel's hasManyThrough across 4 tables
2) https://github.com/staudenmeir/eloquent-has-many-deep
Anyhow, bellow's something you can do to achieve that with Laravel alone:
// Eager loads bursaries, enrolments and courses, but, condition only courses.
$student = Student::with(['bursaries.enrolments.courses' => function($query) {
$query->where('course','LIKE','%B%');
}])->find(1);
$enrolments = collect();
foreach($student->bursaries as $bursary) {
$enrolments = $enrolments->merge($bursary->enrolments);
}
$courses = collect();
foreach ($enrolments as $enrolment) {
$courses = $courses->merge($enrolment->courses);
}
When you do $student->bursaries() instead of $student->bursaries, it returns a query builder instead of relationship map. So to go to enrolments() from bursaries() you need to do a bursaries()->get(). It should look like this.
$student->bursaries()->get()[0]->enrolments(), added the [0] because im using get(), you can use first() to avoid the [0]
$student->bursaries()->first()->enrolments()
But I'm not sure if it will suffice your requirement or not.
I have a user model, and I want to check if a user has been assigned a mentor.
public function mentorapplication()
{
return $this->hasMany(mentorApplication::class, 'user_id');
}
public function mentorAssigned()
{
return ($this->mentorapplication()->status == "counsellorAssigned");
}
when I call $user->mentorAssigned() in tinker I get an undefined property for status.
Any ideas?
A couple of things here. Firstly, your relationship is has-many, which is one-to-many. When you try to use the relationship you should expect a Collection to be returned, rather than a single entity. Therefore trying to access the ->status property on returned collection won't work.
Secondly, when you're trying to access the relationship like this:
$this->mentorapplication()
You will get a HasMany instance, which would allow you to chain on more constraints to the query, just like ->where(...), or ->orderBy(...). You would need to use something like ->get() or ->first() to actually run the query and get the results you're after. You can omit the () here and Laravel will load the relation for you, returning your collection:
$this->mentorapplication
Now, I don't know exactly what it is you're trying to achieve, but say for instance you wanted to see if at least one of the mentorApplication objects assigned to the user has a status of counsellorAssigned, you could do something like this:
public function mentorAssigned()
{
foreach ($this->mentorapplication as $mentorapplication) {
if ($mentorapplication->status == 'counsellorAssigned') {
return true;
}
}
return false;
}
Or you could use Laravel's Collection methods to help you rather than just doing a loop here. There are many approaches you could take so I will just leave it there.
after some digging I still could not find any solid way to retrieve the inverse of a many-to-many polymorphic relation that allows mixed models results.
Please consider the following:
I have several models that can be "tagged". While it is trivial to retrieve for example $item->tags, $article->tags and the inverse with $tag->articles and $tag->items I have no easy way to do something like $tag->taggables to return both articles and items in the same collection. Things get even bumpier as I need to use pagination/simple pagination to the query.
I have tried a few workarounds but the best I could put together still looks crappy and limited. Basically:
I queried the DB once per "taggable";
put all in a single big collection;
passed the collection to a phpleague/fractal transformer (my API uses it) that returns different json values depending on the parsed models.
The limits of this approach is that building a pagination is a nightmare and fractal "include" options can't be used out of the box.
Can anyone help me? I'm currently using Laravel 5.1.
There is not much magic in my current code. Faking and simplifying it to make it short:
From the api controller:
$tag = Tag::findOrDie($tid);
$articles = $tag->cms_articles()->get();
$categories = $tag->cms_categories()->get();
$items = $tag->items()->simplePaginate($itemsperpage);
$taggables = Collection::make($articles)->merge($categories);
// Push items one by one as pagination would dirt the collection struct.
foreach ($items as $item) {
$taggables->push($item);
}
return $this->respondWithCollection($taggables, new TaggableTransformer);
Note: using simplePaginate() is there only because I would like all articles and categories to be shown on first page load while the number of items are so many that need pagination.
From the Transformer class:
public function transform($taggable)
{
switch (get_class($taggable)) {
case 'App\Item':
$transformer = new ItemTransformer;
break;
case 'App\CmsArticle':
$transformer = new CmsArticleTransformer;
break;
case 'App\CmsCategory':
$transformer = new CmsCategoryTransformer;
break;
}
return $transformer->transform($taggable);
}
Please consider that the other transformers are simply returning arrays of data about the models they correlate with. If you use Fractal you would easily spot that nested "included" models would not be applied.
Nothing fancy for the Tag model:
class Tag extends Model
{
protected $morphClass = 'Tag';
protected $fillable = array('name', 'language_id');
public function cms_articles() {
return $this->morphedByMany('App\CmsArticle', 'taggable');
}
public function cms_categories() {
return $this->morphedByMany('App\CmsCategory', 'taggable');
}
public function items() {
return $this->morphedByMany('App\Item', 'taggable');
}
// Would love something like this to return inverse relation!! :'(
public function taggables() {
return $this->morphTo();
}
}
I am also considering the option to do 3 separate calls to the API to retrieve articles, categories and items in three steps. While in this particular scenario this might make sense after all, I would still need to deal with this particular inverse relation headache with another part of my project: notifications. In this particular case, notifications would have to relate to many different actions/models and I would have to retrieve them all in batches (paginated) and sorted by model creation date...
Hope this all makes sense. I wonder if a completely different approach to the whole inverse "polymorphic" matter would help.
Kind regards,
Federico
Ah yes. I was down your path not all that long ago. I had the same nightmare of dealing with resolving the inverse of the relationship of polymorphic relationships.
Unfortunately polymorphic relationships haven't been given much attention in the Laravel ecosystem. From afar they look like unicorns and rainbows but soon you're fighting things like this.
Can you post an example of a $thing->taggable for a better picture? Think it may be solvable with a dynamic trait + accessor magic.
I'm trying to return a Laravel collection object with relations where the resulting collection is based on a nested criteria (ie. a nested model's field value). So it would look something like this:
User -> Category -> Post -> Comments where comment.active == 1
In this case, I want the result to include all of a specific user's categories => posts => comments, where the comment is active. If it is active, it would be nested in the proper hierarchy (Category->Post->Comment). If the comment is not active, any related post and potentially category (if there are no other posts with active comments) should not show up in the collection at all.
I've tried eager loading through with(), load() and filter() with no luck. They will continue to load the relations with empty comment relations. Looking for guidance as to where to research: joins? filters? advanced wheres with nesting?
One attempt:
$user->categories->filter(function($category) {
return $category->isActive();
});
In my model I have all the relationships setup appropriately, and in addition to that I have setup isActive() as follows:
// Category model
public function isActive() {
$active = $this->posts->filter(function($post) {
return $post->isActive();
}
}
// Post model
public function isActive() {
return (boolean) $this->comments()->where('active', 1)->count();
}
This works as expected, but it also includes eagerly loaded nested relationships where comments have an active field of 0. Obviously I'm doing this the wrong way but would appreciate any direction.
Another attempt:
User::with(['categories.posts.comments' => function($q) {
$q->where('active', 1);
}])->find(1);
Unfortunately, this also loads relations (categories and posts) that have no active comments. Replacing the relations with 'categories.posts.isActive' does not work either.
Still confusing because you didn't provide enough code but you may try something like this to get all the users with nested categories.posts.comments without any condition:
$users = User::with('categories.posts.comments')->get();
But it'll give you every thing even when you don't have any comments but to add condition you may try something like this:
// It should return all user models with `categories - posts - active comments`
$users = User::with('categories.posts.activeComments')->get();
Post model:
public function activeComments() {
return $this->hasMany('Comment')->where('active', 1);
}
You may also add more filters using constraints like:
$users = User::with(array('categories.posts.activeComments' => function($query){
$query->whereNull('comments.deleted_at');
}))->get();
But I'm not sure about it, don't know enough about your relationships, so just gave you an idea.