I'm having troubles with a n-n relationship in my Backpackforlaravel app. I have Registrations and Sessions, the setup in the model looks like this:
Registration:
public function sessions()
{
return $this->belongsToMany(\App\Models\Session::class);
}
Session:
public function registrations()
{
return $this->belongsToMany(\App\Models\Registration::class);
}
So the setup seems to be fine, and I also have a registration_session table in my database.
What I want to achieve is, that whenever a Session gets deleted, I want to delete all the entries in the registration_session table, but also all the Registrations. I thought the deletion of the entries in the registration_session table maybe is a standard, but it didn't delete them when I deleted a session. In order to achieve both, I did the following in the destroy function of my SessionCrudController:
public function destroy($id)
{
$this->crud->hasAccessOrFail('delete');
foreach ($this->crud->getCurrentEntry()->registrations as $registration) {
$registration->delete();
}
DB::table('registration_session')->where('session_id', $id)->delete(); //really required?
return $this->crud->delete($id);
}
I have the feeling that I'm doing things way more complicated than I should, so I would appreciate any recommendations.
Update: this is how I store the data initially in the table...the information is coming from a form, so it's not added in a CRUD panel:
DB::table('registration_session')->insert([
'registration_id' => $reg->id,
'session_id' => $sesId
]);
By default, Backpack or Laravel don't concern themselves with deleting related entries, because they assume your Database layer will handle it. With most DBMSs you can specify such rules, and Laravel makes it easy to do so in their migrations. Take a look at foreign key constraints in the Laravel docs, it's pretty easy to build your migration in such a way that any time one item gets deleted, the related items will to, using "cascade":
$table->foreignId('user_id')
->constrained()
->onUpdate('cascade')
->onDelete('cascade');
Related
I trying to learn laravel and to do some tests/demo apps. I've struggling now with laravel/eloquent tables relations. And I need advice.
I have 3 models [Application, Term, AppState] and their tables applications[id, terms_id, appStates_id, and other cols ], terms[id, startDate, endDate, ...], app_states[id, caption]
Application.php
public function term()
{
return $this->belongsTo('App\Term');
}
public function appState()
{
return $this->belongsTo('App\AppState');
}
in Term.php and AppState.php i have:
public function applications()
{
return $this->hasMany('App\Application');
}
How I can get let's say "caption"/"startDay"+"endDate" in blade for each application? I can get their ids $app->terms_id/$app->appStates_id in foreach loop, but i want get caption value from app_states table.
Has to be this relations also specified in migrations? In some tuts is mentioned, that is not needed in case i want to handle it only in laravel.
Thanks for advice
You can access a model's relationship values by calling the relationship method like a property.
$application = Application::find(1);
$application->term->startDate;
$application->term->endDate;
$application->appState->caption;
Also your relationship with AppState is wrong, since your foreign key doesn't follow a snake_case typing, you'll need to provide the appropriate key for it
public function appState()
{
return $this->belongsTo('App\AppState', 'appStates_id');
}
You might also want to check terms_id as well since the model name (Term) is singular but the foreign key is plural.
Has to be this relations also specified in migrations? In some tuts is mentioned, that is not needed in case i want to handle it only in laravel.
Well, yes, you don't need to if Laravel will only be the one accessing that database. But if any cases in the near future you decide to migrate to a different framework or use the same database in another application, it's better to include these relationships in the migration. Also a database administrator would probably cringe if you don't.
So provided your relationships are correctly setup, you can access them anywhere you have an instance of that model.
So for example, lets say you have passed a collection of applications to your view ($apps):
#foreach($apps as $app)
{{ $app->term->startDate }}
{{ $app->term->endDate }}
{{ $app->appState->caption }}
#endforeach
Important Note: We are accessing the Eloquent relationship using ->appState rather than ->appState(). The later is actually accessing a Query Builder instance and has some more advanced use cases
I have a Laravel 5.3 site and I think maybe I have some weird things going on due to some actions happening in API controllers and some happening in the regular controllers.
Or maybe an issue where at some times I am dealing with a Model, and sometimes with an Eloquent Collection.
The issue is, I am trying to retrieve relations on a Model and am getting null.
For instance, I have course Model that relates to week Model.
In course Model I get week items as
public function weeks()
{
return $this->hasMany(Week::class, 'course_id');
}
In backend, these relations get sent in this way:
$course->load('weeks')
All is good.
But when course item gets deleted and I try and take action in the week controller as
static::deleting(function($course) {
$course->weeks->delete();
});
$course->weeks is null. At that time I see in the database that all is good and this course items does indeed have a week item related, but $course shows 0 relations.
So something odd is happening where $course->webinars is not grabbing the week items related.
Is there something that I am fundamentally doing wrong? Maybe it is because in the models I have these sorts of statements:
protected $table = 'Week';
Are these preventing the relations from being pulled? I always thought that is I had some function in a model that returns relations that those relations would always be available when I use syntax $course->weeks.
Ideas?
Thanks again,
You can simply setup migrations to automatically delete from weeks if you delete a course, provided you have foreign key relationship.
If you have a column course_id in weeks table then add this into your migration
$table->foreign('course_id')
->references('id')->on('courses')
->onDelete('cascade')
I think you can use Observers. In your AppServiceProvider, first register the observer.
public function boot()
{
Course::observe(CourseObserver::class);
}
Now, add an Observer class.
class CourseObserver
{
public function deleting(Course $course)
{
$course->weeks()->delete();
}
}
I have two tables posts and sharedposts. sharedposts table has columns "user_id", "updated_at" and "post_id" where as posts table has 'id', 'title' and 'body'. I know about the relations to link both tables. All i want to do is to display each post ordered by 'updated_at' from both the tables. Please help with both query builder and eloquent way. Thanku
The code is not tested, but you can try this:
Post::whereHas('sharedpost',function($query){
$query->orderBy('updated_at');
})->get()
Maybe a bit different approach if there won't be to much of the updates of the models? This way I suppose the read should be faster (somebody please correct me if I'm wrong here)
Add another field to the table by creating new migration and adding
$table->timestamp('last_updated');
Then using Events update the field whenever the Post or SharedPost is updated by adding this to AppServiceProvider:
public function boot()
{
Post::saving(function ($post) {
$post->last_updated = Carbon::now();
});
}
I'm not sure if this will work though and it would be appreciated if you returned a feedback as I'm lazy to try it out myself at the moment :). Worse case scenario you might need to change the method as:
public function boot()
{
SharedPost::saved(function ($sharedpost) {
$sharedpost->post->last_updated = Carbon::now();
$sharedpost->save();
});
}
or you could check out Observers if you don't want the code in the AppServiceProvider. Haven't used it but it seems straightforward.
Then you could simply Post::orderBy('last_updated')->get();
This way you will have one or two more inputs to your database but I think (and guys please correct me if I'm wrong) the get() should be faster. Keep in mind I'm far from a MySQL expert.
And in the end, you can make it even faster by saving this data to Cache using Redis.
I am trying to use a table for my Users and separate table for users' Projects in my database. However I want the names of the fields to be different for user id. What I want to take the id from the 'Users' table; and while saving the created project to the database, use that (user) id as created_by_id in Projects table.
public function store(CreateProjectRequest $request)
{
$project = new Project($request->all());
Auth::user()->projects()->save($project);
// Project::create($request->all());
return redirect('pages/home');
}
Also in Users.php, I added:
public function projects()
{
return $this->hasMany('App\Project');
}
The commented field is working on its own. However, I guess my problem arises because when I comment that line again, and add the other two lines ($project... and Auth::user... bits), I guess it is assuming I have a field in the Projects table named id.
I thought I would work around this problem with changing the primary key but I couldn't find how to take the Auth::user()->id; and make it write that value in created_by_id in a secure way. This is what I found though:
class Project extends Eloquent {
protected $primaryKey = 'created_by_id';
}
Edit: I don't think changing the primary key is my solution.
You can pass a second and third parameter to hasMany() method to specify the keys to use. Documentation
public function projects()
{
return $this->hasMany('App\Article','userid','created_by');
}
Using Laravel, I have the following code
$review = Review::find(1);
$review->delete();
Review has a many to many relationship defined with a Product entity. When I delete a review, I'd expect it to be detached from the associated products in the pivot table, but this isn't the case. When I run the code above, I still see the linking row in the pivot table.
Have I missed something out here or is this the way Laravel works? I'm aware of the detach() method, but I thought that deleting an entity would also detach it from any related entities automatically.
Review is defined like this:
<?php
class Review extends Eloquent
{
public function products()
{
return $this->belongsToMany('Product');
}
}
Product is defined like this:
<?php
class Product extends Eloquent
{
public function reviews()
{
return $this->belongsToMany('Review');
}
}
Thanks in advance.
The detach method is used to release a relationship from the pivot table, whilst delete will delete the model record itself i.e. the record in the reviews table. My understanding is that delete won't trigger the detach implicitly. You can use model events to trigger a cleanup of the pivot table, though, using something like:
protected static function booted()
{
static::deleting(function ($review) {
$review->product()->detach()
});
}
Also, I would suggest that the relationship would be a one to many, as one product would have many reviews, but one review wouldn't belong to many products (usually).
class Review extends \Eloquent {
public function product()
{
return $this->belongsTo('Product');
}
}
class Product extends \Eloquent {
public function reviews()
{
return $this->hasMany('Review');
}
}
Of course, this would then require that you tweak your database structure. If you wanted to leave the database structure and your current relationships as they are, the other option would be to apply a foreign key constraint on the pivot table, such that when either a review or product is removed, you could cascade the delete on the pivot table.
// Part of a database migration
$table->foreign('product_id')->references('id')->on('products')->onDelete('cascade');
$table->foreign('review_id')->references('id')->on('reviews')->onDelete('cascade');
Edit: In adding the constraint, you push the cleanup work onto the database, and don't have to worry about handling it in code.
Simpler Steps:
In this example an Account has many Tags:
To delete the Tags, then the Account do this:
// delete the relationships with Tags (Pivot table) first.
$account->find($this->accountId)->tags()->detach();
// delete the record from the account table.
$account->delete($this->accountId);
On the Pivot Table make sure you have ->onDelete('cascade');
$table->integer('account_id')->unsigned()->index();
$table->foreign('account_id')->references('id')->on('accounts')->onDelete('cascade');
$table->integer('tag_id')->unsigned()->index();
$table->foreign('tag_id')->references('id')->on('tags')->onDelete('cascade');
$review->product()->sync([]) also works.
However $review->product()->detach() is much more explicit.
public function destroy($id)
{
$review = Review::find($id);
$review ->tagged_users()->detach();
return $review ->delete();
}
also works
If that way doesn't solve your problem, you can delete Pivot table records to using the DB option like below ;
DB::table('any_pivot_table')->where('x_column', $xParameter)->delete();
You can solve the problem just like this.
Enjoy your coding !
i guess you have a error in your models relationship conception, the product has many reviews but the review associated with one product so you have here one to many relationship.
but in general the answer in the general case will be using:
$product->reviews()->sync([]);