A Paper can have many Authors and an Author can have many Papers. An Author cannot be listed as an Author more than once on the same Paper.
I've set up the many-to-many relationship in Laravel and I am able to use the attach method to link Authors to a Paper. However, Laravel allows me to add the same Author twice.
Here is a contrived example.
// App\Models\Author
public function papers() {
return $this->belongsToMany (Paper::class);
}
// App\Models\Paper
public function authors() {
return $this->belongsToMany (Author::class);
}
// LinkController
public function store (Author $author) {
$author->papers()->attach (request ("paper")); // works
$author->papers()->attach (request ("paper")); // adds a second link, should do nothing.
}
Obviously I'm hard-coding the second attach above, but users can select the same author twice.
How can I tell Laravel to silently ignore the second request?
I've discovered the syncWithoutDetaching method:
// LinkController
public function store (Author $author) {
$author->papers()->syncWithoutDetaching ([request ("paper")]);
$author->papers()->syncWithoutDetaching ([request ("paper")]); // does nothing.
}
Related
I have those tables :
- blocks
- bloackables
--reports
--modalities
--reportGroups
Block.php :
public function reports()
{
return $this->morphedByMany(Report::class, 'blockable');
}
public function modalities()
{
return $this->morphedByMany(Modality::class, 'blockable');
}
public function reportsGroups()
{
return $this->morphedByMany(ReportsGroup::class, 'blockable');
}
Report.php :
public function blocks()
{
return $this->morphToMany(Block::class, 'blockable');
}
The same type of relationship exists for ReportGroups and Modalities...
Basically I'd like to load a Block instance and then check if the instances of Report, Modality and ReportGroup are related to this block.
The idea is to create an edition form with a checkbox for every Report, Modality or ReportGroup instances).
What are the strategies ? I read the Eloquent documentation but I am still confused...
Best regards,
Take care...
Nicolas
i'm not sure i understand you completely:
you have
$reportInstances,$modalityInstances,$reportGroupInstances
and you want to determine who has relation to the current block;
ok, you should load the model 'block' with its relations, and check the relation existance:
$blcokWithRelations=Block::with(['reports','modalities','reportsGroups'])->find($block->id):
foreach($reportInstances as $reportInstance)
{
if($blcokWithRelations->reports->where('id','=',$reportInstance->id)->get->first()!=null)
// this report has relation to the current block
else
// this report doesn't have relation to the current block
}
the same goes for the rest of relations
I am trying to update/delete/create in belongsTo relations.
Company has many sports
sports is belonging to Company
Here is two models.
class CompanySports
{
public function company()
{
return $this->belongsTo(Company::class, "company_id","id");
}
class Company
public function sports()
{
return $this->hasMany(CompanySports::class,"company_id","id");
}
}
at controller, when sports is added or modified or remove, what is the best practice to update?
i know that many to many, sync can be used. In this, what is the best solution? Should i compare everytime after loading all from database which is not good practice i believe.
From your code, I would first recommend putting your models in separate files, and ensuring they are singular. If you use the artisan make:model command to generate the stubs, it should do this for you.
// app/CompanySport.php // <-- NOTE singular
class CompanySport // <-- NOTE singular
{
public function company()
{
return $this->belongsTo(Company::class, "company_id","id");
}
}
// app/Company.php
class Company {
public function sports()
{
return $this->hasMany(CompanySport::class,"company_id","id"); // singular
}
}
From there, I find it helpful to build helper methods in the various classes so that the grammar sounds natural and more importantly, belongs to the model. For example:
// app/Company.php
class Company
{
...
public function addSport(CompanySport $sport)
{
$this->sports()->save($sport);
}
public function removeSport(CompanySport $sport)
{
$this->sports()->find($sport->id)->delete();
}
}
These helper functions can then be easily called from anywhere, e.g. controller:
// CompanySportsController.php
public function store(Company $company, CompanySport $sport)
{
$company->addSport($sport);
return redirect('/company/' . $company->id);
}
If you are using these helpers, there is no comparing or sync to be done since you are only using a one to many relationship. Eloquent does everything for you.
Also, I've found this cheatsheet particularly helpful when building out the initial relationships and scaffolding of a new app.
While adding new record of Company Model, you need not to do anything as there is no child for it yet.
While updating an instance of a Company model, again you need not to update anything on its children. As relationship are based on id(primary key) which I believe you don't change while updating.
And now for deleting there are some questions. Do you want to delete the children when the parent is deleting? If so, you can use ON DELETE CASCADE which you can set up in migration like
$table->foreign('company_id')->references('id')->on('companies')->onDelete('cascade');
in your spors table.
Well you can make your own function too like answered in here
Well if you don't want to delete the children, you can use softdelete on your Model. set up the relations then like
CompanySports
public function company()
{
return $this->belongsTo(Company::class, "company_id","id")->withTrashed();
}
This way you can get the parent of a children without any error though the parent is deleted.
I am using laravel 5.7. I have now a situation where i have a Fight model with structure user_id, fightable_id
i have two other tables users and monsters. so users_id refers to users (a user can have many fights) and fightable_id can refer to either a user or a monster (monsters table). so I have to define the functions for the relation ship
for User model i have to do
1.for polymorphic one to many relationship
public function fights()
{
return $this->morphMany('App\Fight', 'fightable');
}
2.for simple one to many relationship
public function fights()
{
return $this->hasMany('App\Fight');
}
I am confused now. ofcourse the only way is to change the functions name. but i will be doing the correct thing by changing the function names right (as both the functions have same name). or is there anything I am doing wrong?
I'm not sure I understand your question completely but I'll try my best!
Also this post will really help you understand the problem you are facing I think,
Laravel morph relationship
Using the code from the post I linked but taking your tables would produce models defined like this.
User Model
class User extends Model
{
public function fights()
{
return $this->hasMany('App\Fight');
}
}
Fight Model
class Fight extends Model
{
public function user()
{
return $this->belongsTo('App\User');
}
public function fightable()
{
return $this->morphTo();
}
}
Monster Model
class Monster extends Model
{
public function fight()
{
return $this->morphOne('App\Fight', 'fightable');
}
}
If you still feel this has not answered your question or need some more help just let me know!
I have two models
Post.php
id
post
show_id
type = 'movie' or 'tv'
Show.php
id // this only auto increment counter ids
show_id
show_type = 'movie' or 'tv'
the thing is show can be either tv or movie and may two with the same show_id for exmaple one tv could have a show_id of 10 and also one movie can have it but the types are diffrent
i have in post model
public function show(){
return $this->belongsTo('App\Show', 'show_id');
}
in show model
public function post(){
return $this->hasMany('App\Post', 'id');
}
this relationship get the first show with matching show id it sees, wheather its a movie or tv, i want to restrict it to match type column on both sides
post.php:
public function show() {
return $this->belongsTo('App\Show', 'show_id', 'show_id')
->where('type', $this->type);
}
show.php
public function posts() {
return $this->hasMany('App\Post', 'show_id', 'show_id')
->where('type', $this->show_type);
}
UPDATE (the code above does not work!)
Trying to use where clauses (like in the example below) won't work when eager loading the relationship because at the time the relationship is processed $this->f2 is null.
Read more here: Compoships
I just came accross a package https://github.com/topclaudy/compoships
what it does it allows creating relationships based on more than one FK, which laravel doesnt support by default
I think what you're looking for is a polymorphic relation. Instead of having a model that may be one of two "types" there should probably be two separate models on the same relation. For example:
class Post
{
public function Show()
{
return $this->morphTo();
}
}
class TvShow
{
public function Post()
{
return $this->morphMany('App\Post', 'show');
}
}
class Movie
{
public function Post()
{
return $this->morphMany('App\Post', 'show');
}
}
Then your posts table would have a show_id and show_type field that would relate to either a tv show or movie. Check out the docs for more info, I'm not sure of the rest of your project so I'm not 100% this will fit but anytime you start putting "_type" fields in your table you should question whether or not you should be using a polymorphic relation. This will also likely keep your models cleaner and free of a bunch of if statements as you realize there are other differences between movies and shows and how you handle them.
https://laravel.com/docs/5.7/eloquent-relationships#polymorphic-relations
I have three tables - "courses", "lessons" and "tasks". Each lesson belongsTo a course, and each task BelongsTo a lesson. I want to output a task, showing the task name, the lesson name, and the course name. How do I access the course table data? To get the lesson information linked to a course, I have used the following in my Task model:
$lessonName = $this->lessons->lesson_name;
To get the course name associated to that lesson, I have tried the following with no success, but I am really guessing here:
$courseName = $this->lessons->courses->course_name;
My model relationships are as follows:
Course.php
public function lessons()
{
return $this->hasMany('App\Lesson');
}
Lesson.php
public function tasks()
{
return $this->belongsTo('App\Task', 'task_id', 'id');
}
Task.php
public function lessons()
{
return $this->belongsTo('App\Lesson', 'lesson_id', 'id');
}
Where am I going wrong? Thanks
there is another way you can do this by using accessors.
on your Task model do the following:
public function getLessonAttribute(){
return Lesson::where('id', $this->attributes[*foreign_key_field*])->first();
}
Here you receive all the data regarding the lesson that the task belongs to, and can use them as any other attribute (field) of the model.
on your Lesson model get the course that it belongs to.
public function getCourseAttribute(){
return Course::where('id', $this->attributes[*course_foreign_key_field*])->first();
}
and then assuming that $task is your collection, you can access the lesson and the course like the following in blade:
$task->lesson->lesson_name and $task->lesson->course->course_name
In your lesson.php model doesn't exist relationship courses so there are your issue. Use answer what is told you #jeroenF
So you want the inverse of hasManyThrough?
The hasManyThrough feature of Laravel (see their site) facilitates connecting your Courses to Task directly, without having the intermediate connection in a separate relationship.
You are looking for the inverse?