Which relation to use in Laravel to bind two table through third?
When Doctors can be assigned to some Centers. The intermediate table will be as:
doctor_id | center_id
How to create model in Laravel for this case?
You don't need a model for the intermediate table, simply use attach
Example:
$center = Center::create();
$doctor = Doctor::find(1);
$doctor->centers()->attach($doctor->id);
This is a very simple example but should give you the idea, of how to approach it.
All of it of course requires you have set up your Center and Doctor model with the correct many to many relations
Doctor.php model:
public function centers()
{
return $this->belongsToMany(Doctor::class);
}
See the documentation, for more information.
You could obviously create a model called DoctorsCenter and create it manually by doing this, whenever you want to attach a relation.
DoctorsCenter::create(['center_id' => $center->id, 'doctor_id' => $doctor->id]);
I don't see any good reason for doing this, and would not recommend it.
You can use hasMany or belongsTo relationship of Laravel.
See the laravel documentation, for more information
Related
I am very new to Laravel and quite confuse with the model and database thing. I understand that a model represent one table. So I created a model using artisan command without migration and it created the code as follow.
namespace App;
use Illuminate\Database\Eloquent\Model;
class RegCars extends Model
{
//
}
Since I have a different table name, so I add protected $table = 'regcars'; and assume that this model can now access the table by running query such as RegCars::where('user_id', $user_id); from controller. But I wasn't able to get anything by running it.
So I am wondering, how does this model able to run the query? Is the migration needed in order to do this? Is there still other area I need to set before I can run any query?
highly recommend to read docs or at least watch a tutorial.
what you get is a query build not a model or a collection of models. laravel(eloquent) doesnt exactly know what you want so you query database then get the data by methods that laravel gives you if assume you want a RegCars you need a method like first:
RegCars::where('user_id', $user_id)->first(); // now you have model
more info: https://laravel.com/docs/8.x/eloquent
Following the official documentation it is very easy to define a relationship between two models. However, One of my models just need to access data from 4 different table in a one to one basis. Those tables will have no functionality. So, I don't want to build a model for them.
For example I can do this,
class User extends Model
{
public function phone()
{
return $this->hasOne('App\Phone');
}
}
Here to complete this relationship successfully I need to have a Phone model. However, if I don't have a model can I use just the table name to define relationship? I want to use something like, return $this->hasOne(DB::table('phones');.
I reckon, if I can somehow use this I will have less models to work with which will make my code more manageable. Is it a good practice?
is there any way to get the defined relationships in eloquent model. I have a situation where I need to get the model relationships so I can update all other eloquent models that relies on a specific id before delete it
There's no unified method to iterate over all registered relationships of a class. You can, however, access all the currently loaded relationships of a model instance (via the ->relations attribute or the getRelations() method), but that's not what you're up to. I'd suggest you take a look at laravel's documentation on inserting and updating relationships. So far that's the best laravel provides out of the box, the rest is developing approaches.
Try this function:
public function getRelations()
You can use
$model->getRelations()
function to get all relations
Also refer below link for details https://laravel.com/api/5.7/Illuminate/Database/Eloquent/Concerns/HasRelationships.html#method_getRelations
I unfortunately need to import data from a third-party vendor and use their non-standard database schema with my laravel project. In addition, I need to store multiple "firms," each with their own set of users in my database.
I'm trying to figure out the best way (if it can be done) to use Eloquent to handle the relationships between these tables. So for instance, with my table structure like this:
BmPerson
'id',
'firmId',
'personId'
BmCoverage
'id',
'firmId',
'personId',
'securityId'
BmSecurity
'id',
'firmId',
'securityId'
... for instance, I need to associate a "BmPerson" with many "BmSecurity" through the "BmCoverage" table.
But I need to somehow use composite keys, because I am storing multiple "firms" in each table (per the 3rd party vendor's database schema).
One approach I've used so far is scoping, e.g.: for my BmCoverage model:
public function scopeFromFirm($query,$firmId){
return $query->where('firmId','=',$firmId);//->where('personId','=',$personId);}
public function scopeFromPerson($query,$personId){
return $query->where('personId','=',$personId);//->where('personId','=',$personId);}
Then I can retrieve the coverage list for an individual person, but I still need to somehow be able to associate the "BmCoverage" with the "BmSecurities." I suppose I could just add a scope the BmSecurities class too, but it would be nicer to just use Eloquent.
Has anyone come up with a good way to use composite keys in laravel model relationships, or should I just stick with the scoping method?
There is a package here that seems to be perfect for your case:
Compoships offers the ability to specify relationships based on two
(or more) columns in Laravel 5's Eloquent. The need to match multiple
columns in the definition of an Eloquent relationship often arises
when working with third party or pre existing schema/database.
You would use it like this:
class BmPerson extends Model
{
use \Awobaz\Compoships\Compoships;
public function bmCoverages()
{
return $this->hasMany('App\BmCoverage', ['firmId', 'personId'], ['firmId', 'personId']);
}
}
If every BmSecurity belongs to exactly one BmCoverage, and every BmCoverage belongs to exactly one BmPerson its probably easier to replace 'firmId', 'personId' with bmperson_id in BmCoverage DB; and 'firmId', 'securityId' with bmcoverage_id in BmSecurity. Then you can use default hasMany relations with one key.
Everything you need for this can be found here https://laravel.com/docs/5.2/eloquent-relationships
You can easily define which cols sohuld be the referenced key.
Example:
public function bmCoverages() {
return $this->hasMany('App\BmCoverage', 'firmId', 'id');
}
This would probably belong to your App\Firm or whatever it is called.
In general the hasMany relations looks like this
return $this->hasMany('App\Comment', 'foreign_key', 'local_key');
As you can see you can specify the keys.
As the others have said, you need to use the HasMany and HasManyThrough relationship.
Here from your table definitions, you simply need access to:
Person->BmCoverage(s)
Person->BmSecurity(s) of an individual.
What I think is the major problem here is linking the BmSecurity with BmCoverage as apparently there's no coverage_id per BmSecurity but rather, a composite mapping through firmId and securityId.
In this case, Laravel does not officially support composite keys unfortunately, although you could use a trait like this... but you could also achieve the same with some tricky hasMany.
i.e. on BmCoverage
$this->hasMany('BmSecurity', 'securityId', 'securityId')
->andWhere('firmId', '=', $this->firmId);
Same applies for BmSecurity from BmPerson using HasManyThrough.
Hope that helps.
read laravel hasManyThrough relationship . it will help you to write this query more easily
https://laravel.com/docs/5.1/eloquent-relationships#has-many-through
There's a missing link I fail to understand.
I use migrations to create database tables and I define the relationships there. meaning.. if I have a person table and a job table and I need a one to many relationship between the person and jobs, I'd have the job table contain a "person_id".
When I seed data or add it in my app, I do all the work of adding the records setting the *_id = values etc.
but somehow I feel Laravel has a better way of doing this.
if I define that one to many relationship with the oneToMany Laravel Eloquent suports:
in my Person model.....
public function jobs()
{
return $this->hasMany('Jobs);
}
what's done on the database level? how do I create the migration for such table? Is Laravel automagically doing the "expected" thing here? like looking for a Jobs table, and having a "person_id" there?
Yep, Laravel is doing what you guess in your last paragraph.
From the Laravel documentation for Eloquent Relationships (with the relevant paragraph in bold):
For example, a User model might have one Phone. We can define this
relation in Eloquent:
class User extends Model {
public function phone()
{
return $this->hasOne('App\Phone');
}
}
The first argument passed to the hasOne method is the name of the
related model. Once the relationship is defined, we may retrieve it
using Eloquent's dynamic properties:
$phone = User::find(1)->phone;
The SQL performed by this statement
will be as follows:
select * from users where id = 1
select * from phones where user_id = 1
Take note that Eloquent assumes the foreign key of the relationship based on the model name. In this case, Phone model is assumed to use a user_id foreign key.
Also note that you don't actually have to explicitly set the foreign key indexes in your database (just having those "foreign key" columns with the same data type as the parent key columns is enough for Laravel to accept the relationship), although you should probably have those indexes for the sake of database integrity.
There is indeed support to create foreign key relationships inside migration blueprints and it's very simple too.
Here is a simple example migration where we define a jobs table that has a user_id column that references the id column on users table.
Schema::create('jobs', function($table)
{
$table->increments('id');
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users');
});
You can also use some other methods that laravel provides such as onDelete() or onUpdate
Of course to understand better the options that are available to you please read the documentation here.
Edit:
Keep in mind that Eloquent is just using fluent SQL wrapper and behind the scenes there are just raw sql queries, nothing magical is happening, fluent just makes your life a lot easier and helpers you write maintainable code.
Take a look here about the Query Builder and how it works and also, as #Martin Charchar stated , here about Eloquent and relationships.