laravel one-to-many get data without inner join - laravel

I am trying to get a feel around the laravel ORM and I have the following models.
I have a:
user table with- id, firstname, lastname
city table with - id, name
usercity table with - user_id, city_id
The usercity table tracks the cities the user has visited.
I added the following in city model:
public function usercity()
{
return $this->hasMany('App\UserCity');
}
And another function in user model
public function usercity()
{
return $this->hasMany('App\UserCity');
}
I also added a model for UserCity and added following function there.
public function city()
{
return $this->belongsTo('App\City');
}
public function user()
{
return $this->belongsTo('App\User');
}
Now, the goal is to retrieve all the cities a user has visited. I used the following function.
$usercities = User::where('id','=',1)->first()->usercity()->get();
This works in the sense that it retrieves the user_id and city_id.
What would i need to do to get all the fields in the city table also?
Current response:
[[{"user_id":"1","city_id":"1"},{"user_id":"1","city_id":"2"},{"user_id":"1","city_id":"3"},{"user_id":"1","city_id":"4"}]]
I might be able to use inner join but I wanted to see if there was another way to retrieve the data which safely populates the data for me.

What you really have is a many-to-many relationship between users and cities, with the usercity table being the pivot table. Laravel uses the BelongsToMany relationship to implement this. You'll need to make a few changes to get this to work.
In your city model:
public function users() {
return $this->belongsToMany('App\User', 'usercity');
}
In your user model:
public function cities() {
return $this->belongsToMany('App\City', 'usercity');
}
You can get rid of the UserCity model. There is usually no reason to need a model for the pivot table.
The usercity table may need to be updated to add an id field as the primary key. I've not tried it without one, however, so it may work as you have it. Also, if you wanted, you could rename the table to city_user to conform to Laravel conventions, and then you wouldn't need to specify the table name in the relationship definitions.
Once your relationships are setup correctly, you can access a user's cities via the cities relationship on the user, and you can access a city's users via the users relationship on the city. For example:
// all of the cities visited by user 1
$user = User::find(1);
$usercities = $user->cities;
// all of the users that have visited city 1
$city = City::find(1);
$cityusers = $city->users;
You can find more information about the relationships in the documentation here.

Related

Invalid argument supplied for foreach() in laravel when use Eloquent: Relationships

I wanna get the class name of a user via the user ID. When I input the ID of a user so I will wanna get the class name. I have three tables such as users table, classes table, and class_users table. The class_users table is born from two users table and classes table.
A users table has an id, name, email, password.
A classes table has an id, class_code, class_name.
A class_users table has an id, class_id, user_id
And this problem relates to Eloquent Relationships.
Thank you for help.
My Route:
Route::get('/find_classes/{id}','StudentController#find_classes');
My Controller function:
public function find_classes($id)
{
$users = User::find($id);
foreach($users->classes as $class)
{
echo $class->name . '<br';
dd($class);
}
}
My User Model:
public function classes()
{
return $this->belongsTo('App\Classes','class_users','user_id','class_id');
}
Looks like you might have the wrong relationship set up on your User model. You have a one to many set up, but your DB is setup to handle a many to many. I suggest you change your User model relationship:
public function classes()
{
return $this->belongsToMany('App\Classes');
}
Note, you may need to name the FK on that relation, as I see you have class_id on the table, but your actual class is named 'Classes'. Check through your relationships to ensure this is explicit on the FK where it doesn't follow Laravel convention exactly.
With this relationship, your foreach loop should work. It would be a good idea for efficiency, as mare96 noted, to eager load the classes on the $users collection when you query:
$users = User::with('classes')->find($id);

Laravel pivot with multiple columns

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;

Query all where list id has user id

I'm trying to get all the properties, in a watchlist(s) where the list has a user id.
The relationship is set up as follows.
Each watchlist is related to a user id. Each Property has a watchlist id.
I need all properties, in all the watchlists belonging to that user.
The watchlist gets the user_id automatically upon creation.
Here are my models
Watchlist
public function properties(){
return $this->hasMany('App\WatchedProperties');
}
public function user(){
return $this->belongsTo('App\User');
}
WatchedProperties
public function watchlist(){
return $this->belongsTo('App\Watchlist');
}
Query
Gets all books in every list disregarding user ids and list ids
$Watchlists = WatchedBooks::all();
Currently gets all books regardless of userid.
I need all books in all of the user's lists.
A user could have multiple lists
List A
List B
So something like
All books from all lists where the list id is related to user id.
This is what the Watchlist DB looks like
WatchlistDB
This is what the WatchedBooks DB looks like
Books in watchlist
Laravel has a beautiful solution for this: you can add a ->hasManyThrough relation to the user model. You can find more information about this type of relation in the Laravel documentation about Eloquent relationships.
The user model will look like this:
class User extends Model {
[...]
public function watchedBooks()
return $this->hasManyThrough('App\WatchedBook', 'App\Watchlist');
}
[...]
}
Then you can get all the WatchedBooks, associated with the user, using
$user->watchedBooks;
or
$user->watchedBooks()->yourBuilderQueryHere()->get();
whereHas allows you to query in relationships. More information on this can be found at https://laravel.com/docs/5.6/eloquent-relationships#querying-relationship-existence
$Watchlists = WatchedBooks::whereHas('watchlist', function($query) use ($user_id){
$query->where('user_id', $user_id)
})->get();
The script above gets all WatchedBooks that are associated with a Watchlist that is owned by a user ($user_id).

Laravel: return multiple relationships

I have the following table:
The table is called user_eggs and it stores the user eggs.
eggs are items with additional data (hatch_time)
As you can see, user 2 has 2 eggs, which are items 46 and 47.
My items table stores the item general information such as name, image, description, etc...
How I can return the user eggs using $user->eggs() including the item data in my items table of the egg item_id?
I tried:
User Model:
/**
* Get the eggs
*/
public function eggs()
{
return $this->belongsToMany(Egg::Class, 'user_eggs','user_id','item_id')
->withPivot('id','hatch_time');
}
but $user->eggs() returns an empty array.
Any ideas?
A simple approach will be:
in your UserEgg model define:
/**
* Get the user associated with egg.
*/
public function _user()
{
return $this->belongsTo('App\User','user_id');
}
/**
* Get the item associated with egg.
*/
public function item()
{
return $this->belongsTo('App\Item','item_id');
}
then in your controller:
use the model to extract everything like this:
$userEggs = UserEgg::where('user_id',2)->get();
foreach($userEggs as $userEgg){
$associateduser = $userEgg->_user;
$associatedItem = $userEgg->item;
}
Short answer
If you loop through the user's eggs:
foreach($user->eggs as $egg){
$item = Item::find($egg->pivot->item_id);
}
If you want to query:
$user->eggs()->wherePivot('item_id', 1)->get();
Long answer
From the Laravel Documentation
Retrieving Intermediate Table Columns
As you have already learned, working with many-to-many relations requires the presence of an intermediate table. Eloquent provides some very helpful ways of interacting with this table. For example, let's assume our User object has many Role objects that it is related to. After accessing this relationship, we may access the intermediate table using the pivot attribute on the models:
$user = App\User::find(1);
foreach ($user->roles as $role) {
echo $role->pivot->created_at;
}
Notice that each Role model we retrieve is automatically assigned a pivot attribute. This attribute contains a model representing the intermediate table, and may be used like any other Eloquent model.
By default, only the model keys will be present on the pivot object. If your pivot table contains extra attributes, you must specify them when defining the relationship:
return $this->belongsToMany('App\Role')->withPivot('column1', 'column2');
If you want your pivot table to have automatically maintained created_at and updated_at timestamps, use the withTimestamps method on the relationship definition:
return $this->belongsToMany('App\Role')->withTimestamps();
Filtering Relationships Via Intermediate Table Columns
You can also filter the results returned by belongsToMany using the wherePivot and wherePivotIn methods when defining the relationship:
return $this->belongsToMany('App\Role')->wherePivot('approved', 1);
return $this->belongsToMany('App\Role')->wherePivotIn('priority', [1, 2]);

Laravel and pivot table to relate different model

I'm wondering how, but it's bit confusing.
I have fine belongs to many relation between users and groups tables as well as appropriate models for all of that.
But i also have table students, where not all users are student so i students table i maintain user_id field.
My question would be: Can i use pivot table "group_user" for relations between student and group model, in students table i have "user_id" field? and how?
I tried something like
public function students()
{
return $this->belongsToMany('Student','group_user','group_id','user_id');
{
but i don't see the way how to tell eloquent not to take students.id but to take students.user_id???
Assuming these relations:
Subject belongsTo Group
Group belongsToMany User
User hasOne Student
you can easily do this:
$subject = Subject::find($someId);
// of course for multiple subject use eager loading:
// $subjects = Subject::with('group.users.student')->get();
$users = $subject->group->users; // related users
foreach ($users as $user)
{
$user->student; // null|student model
}

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