I have a teacher model and that teacher has a belongToMany relationship with a student model.
I want to leverage a higher order message function to sync a student to many teachers.
Usually I would do the following:
$teachers = Teacher::limit(5)->get();
$student = Student::first();
$teachers->each(function($teacher) use ($student) {
$teacher->students()->sync($student)
});
With higher order functions I should be able to do:
// Throws error BadMethodCallException: Method Illuminate\Database\Eloquent\Collection::sync does not exist.
$teachers->each->students()->sync($student);
Unfortunately due to how higher order messages work as defined inside of the class HigherOrderCollectionProxy the relationship students() will be executed returning a collection of all the students that teacher has instead of a belongsToMany relationship instance.
How can I use higher order messages with Laravel Eloquent relationships?
Reverse the logic.
$teacherIds = Teacher::limit(5)->pluck('id')->toArray();
$student = Student::first();
$student->teachers()->sync($teacherIds);
Related
I'm new to Laravel. I am developing a project. and in this project I have 4 tables related to each other
-Users
-Orders
-OrderParcels
-Situations
When listing the parcels of an order, I want to get the information of that order only once, the user information of that order once again, and list the parcels as a table under it. so far everything ok. but I also want to display the status of the parcels listed in the table as names. I couldn't add the 4th table to the query. do you have a suggestion? I'm putting pictures that explain the structure below.
My current working code is
$orderParcels = Orders::whereId($id)
->with('parcels')
->with('users:id,name')
->first();
and my 'orders' model has method
public function parcels(){
return $this->hasMany(OrderParcels::class);
}
public function users(){
return $this->hasOne(User::class,'id','affixer_id');
}
Note[edit]: I already know how to connect like this
$orderParcels = DB::table('order_parcels as op')
->leftjoin('orders as o','op.orders_id','o.id')
->leftjoin('users as u','o.affixer_id','u.id')
->leftjoin('situations as s','op.status','s.id')
->select('op.*','o.*','u.name','s.situations_name')
->where('op.orders_id',$id)->get();
but this is not working for me, for each parcels record it returns me orders and user info. I want once orders info and once user info.
Laravel provides an elegant way to manage relations between models. In your situation, the first step is to create all relations described in your schema :
1. Model Order
class User extends Model {
public function parcels()
{
return $this->hasMany(OrderParcels::class);
}
public function users()
{
return $this->hasOne(User::class,'id','affixer_id');
}
}
2. Model Parcel
class Parcel extends Model {
public function situations()
{
return $this->hasOne(Situation::class, ...);
}
}
Then, you can retrieve all desired informations simply like this :
// Retrieve all users of an order
$users = $order->users; // You get a Collection of User instances
// Retrieve all parcels of an order
$parcels = $order->parcels; // You get a Collection of User instances
// Retrieve the situation for a parcel
$situations = $parcel->situations // You get Situation instance
How it works ?
When you add a relation on your model, you can retrieve the result of this relation by using the property with the same name of the method. Laravel will automatically provide you those properties ! (e.g: parcels() method in your Order Model will generate $order->parcels property.
To finish, in this situation where you have nested relations (as describe in your schema), you should use with() method of your model to eager load all the nested relation of order model like this :
$orders = Orders::with(['users', 'parcels', 'parcels.situations'])->find($id)
I encourage you to read those stubs of Laravel documentation :
Define model relations
Eager loading
Laravel Collection
Good luck !
Use join to make a perfect relations between tables.
$output = Orders::join('users', 'users.id', '=', 'orders.user_id')
->join('order_parcels', 'order_parcels.id', '=', 'orders.parcel_id')
->join('situations', 'situation.id', '=', 'order_parcels.situation_id')
->select([
'orders.id AS order_id',
'users.id AS user_id',
'order.parcels.id AS parcel_id',
'and so on'
])
->where('some row', '=', 'some row or variable')->get();
How to create where clause on laravel model attribute
I have the following relation between user and books. where user hasMany books and the book model belongs to single user
I want to select all books with pages > 100 that belongs to user_id = 2
I use laravel 5.2 with mysql and defined a model for User and another model for Book
When I want to get all books for specific user, I user
return User::find(2)->books;
and this works fine. But I want to get the books where pages > 100. I use:
return User::find(2)->books->where([['pages', '>', 100], ['chapters', '>', 3]]);
but doesn't work
User model:
class User extends Authenticatable
{
public function books()
{
return $this->hasMany('App\Book');
}
}
Book model
class Book extends Model
{
public function user()
{
return $this->belongsTo('App\User');
}
}
I expect to get all the books with user_id = 0 and pages > 100 and chapters > 3
You'll want to access the relationship method books(), not the property books. Some quotes from the documentation:
Querying Relations
Since all types of Eloquent relationships are defined via methods, you may call those methods to obtain an instance of the relationship without actually executing the relationship queries. In addition, all types of Eloquent relationships also serve as query builders, allowing you to continue to chain constraints onto the relationship query before finally executing the SQL against your database.
Relationship Methods Vs. Dynamic Properties
If you do not need to add additional constraints to an Eloquent relationship query, you may access the relationship as if it were a property.
Example solution:
return User::find(2)
->books()
->where([['pages', '>', 100], ['chapters', '>', 3]])
->get();
Note that we're using books() to access the HasMany relationship, and using the where() query builder method on it to create a constraint. Then, in order to complete and execute the query, we call get() at the end. If you don't, you'll just return the daisy chained query builder.
Your previous code might not error, because the value returned from User::find(2)->books will be a Collection object, which actually has a where() method. It just likely didn't have any matches because of the array format you passed.
To add where clouses on related models, we can use whereHas() function.
Since you want Books, Start from Book model.
$books = Book::where([
['pages', '>', 100],
['chapters', '>', 3],
])
->whereHas('user', function($query) {
$query->where('id', 2);
})
->get();
Hi I have a problem with Laravel`s pivot table.
I have the following tables: students, courses and lessons.
The table lessons is connected with courses through a foreign key courses_id, and the tables students and courses are connected through a pivot courses_students.
So I can access the information through students like this:
//Students model
public function courses()
{
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->with('lessons');
}
//Courses model
public function lessons()
{
return $this->hasMany(Lesson::class);
}
This works completely fine for this kind of relationship, but I want to add a third column in the pivot with name lesson_id for the lessons table.
I am doing this because, sometimes I need to get a specific set of lessons from each course for each user.
I succeeded in doing so, by using a model courseStudent for the pivot table.
Using the model for pivot my calls became like this.
Student->with('courseStudent.courses')
->with('courseStudent.lessons')
->get();
This partially does what I need it to do, but I want to maintain the relation ship between courses and students.
Is there a way to achieve that?
Example from docs(go through Many To Many):
return $this->belongsToMany('App\Role')->withPivot('column1', 'column2');
Pivot table is meant to use belongsToMany relationship on both entities.
So your students and courses should have it defined if you want pivot table between that is using eloquent default capacity.
As a side note pay attention on naming convention because that way you will reduce issues on minimum: pivot table should be tableanamesingular_tablebnamesingular where order is set by alphabetical order of tables' names (i.e. post_user Yes, user_post No).
Id fields in pivot table should be tablenamesingular_id.
You can set names however you want but this way you will have less unepected behavior in future using eloquent. All of this you have in documentation page and I recommend you go through it thoroughly.
Other way is to use dynamic properties for getting certain values. Example from docs:
$user = App\User::find(1);
foreach ($user->roles as $role) {
echo $role->pivot->created_at;
}
If you would like to manually change values in pivot table, you should create separate model for it that would be connected with that entity/table (pay attention that pivot model extends Pivot as in example from docs rather than Model):
<?php
namespace App;
use Illuminate\Database\Eloquent\Relations\Pivot;
class PostUser extends Pivot
{
// other definitions related
}
You can use join for third relation:
public function courses(){
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->withPivot('lesson_id')
->join('lessons','lesson_id','=','lessons.id')
->select('lessons.id','lessons.title', ...);
}
If you are going to use the same pivot table for courses and lessons, you can to do something like this:
//Students model
public function courses()
{
return $this->belongsToMany(Courses::class,'courses_students','student_id', 'course_id')
->whereNotNull('course_id');
}
public function lessons()
{
return $this->belongsToMany(Lessons::class,'courses_students','student_id', 'lesson_id')
->whereNotNull('lesson_id');
}
Then just use it:
$courses = $student->courses;
$lessons = $student->lessons;
I have a complicated relationship I'm trying to establish between two models.
The goal is to use $supplier->supply_orders to access the orders where the user supplies an item.
This throws: LogicException: Relationship method must return an object of type Illuminate\Database\Eloquent\Relations\Relation.
With the code I've got I can use $supplier->supply_orders()->get(), however, when I try to use it as a relationship it throws. Since this is a relationship I should be able to wrap it in a relationship, but how would I go about doing that?
Supplier Model:
class Supplier extends Model {
public function supply_orders() {
return Order::query()
->select('order.*')
->join('item_order', 'order.id', '=', 'item_order.order_id')
->join('item', 'item_order.item_id', '=', 'item.id')
->where('item.supplier_id', '=', $this->id);
}
}
~~~ A whole lot of back info that I don't think you need but might ~~~
sql tables:
supplier
- id
items:
- id
- supplier_id
item_order:
- id
- order_id
- item_id
orders:
- id
The other Eloquent Models:
class Item extends Model {
public function orders() {
return $this->belongsToMany('Order');
}
}
class Order extends Model {}
Example of how this should work:
$supplier = factory(Supplier::class)->create();
$item = factory(Item::class)->create([
'supplier_id' => $supplier->id,
]);
$order = factory(Order::class)->create();
$order->items()->attach($item);
$orders = $supplier->supply_orders // Throws LogicException
This throws: LogicException: Relationship method must return an object of type Illuminate\Database\Eloquent\Relations\Relation
Sounds like a hasManyThrough with a many to many relationship. Laravel has no inbuilt support for this but you can always go ahead and write your own relationship like this: https://laravel.io/forum/03-04-2014-hasmanythrough-with-many-to-many
If you dont want relationships you can always do something like:
Order::whereHas('items.supplier', function($query) use($supplier) {
$query->where('id', $supplier->id);
});
For this to work, you need to have a relationship function items in your Order model and a relationship function supplier in your item model
I believe the reason it throws a relationship error is that you haven't created an Eloquent relation for
$supplier->supply_orders.
Instead, Laravel looks at your supply_orders() as a method in the class, and thus can't figure out which table to use as the pivot. To get the base relationship to work within Eloquent, you'd need to create a new pivot table for the relationship between suppliers and orders something like:
suppliers
-id
orders
-id
order_supplier
-id
-order_id
-supplier_id
From here, Laravel will accept a simple many to many relationship between the two (this would not cause a failure):
Supplier Class:
/**
* Get all orders associated with this supplier via order_supplier table
*
* #return \Illuminate\Database\Eloquent\Relations\BelongsToMany
*/
public function orders(){
return $this->belongsToMany("\App\Order");
}
Now that the relationship is solid both between the suppliers and orders, as well as the orders and items, you can eager load the relationship in all directions. Where it gets complicated for your particular need with the current DB setup is that you have a 3rd parameter from the items table that is not a direct pivot. Without having to re-structure the DB, I think the easiest would be to load your suppliers and the relationships like normal:
$suppliers = Supplier::with('orders', function($query) {
$query->with('items');
});
From here you've got all the relationships loaded and can draw down the ones with the right item->ids in a follow-up to the $suppliers collection. There are quite a few ways to skin the cat (even including all in one query) now that you have the Eloquent relationship... but I tend to keep it a little more simple by breaking it into a few readable bits.
Hope this helps.
I have a question. Activity model and User model have many-to-many relationships. I know I can get pivot model like this:
$activities = $user->activities;
foreach($activities as $activity)
{
$pivot = $activity->pivot;
}
But now I already have two model instance:$user and $activity .Get them by id individually. Not access from their relationship. So I want to know is there a method to get their pivot model?
Its not necessary for you to call the relationship chain to access pivot, you can query individual model and access pivot too,
$model = Activity::find(1); //get the activity model by primary key
$model->pivot->activityId;