I have this schema
All the relations here must be one-to-zero/one.
A user can be either an employee or a customer. The user_type ENUM gives me the type so I know where to go from there.
Then an employee can be either basic or a manager. The employee_type discriminator let's me know that.
How am I supposed to build the Eloquent Model relations?
Let's say I have a user that is an employee. I need to get it's common fields from the users table but also need to get common fields from employees table. Do I need to hard code, and know that when user_type=emp I need to select from the employees table? What if I need to add another user type later?
UPDATE
Would it make sense to change my schema into something simpler?
My problem is that by using, as suggested, polymorphic relations I would end up to something like this:
$user = new User::userable()->employable()->...
Would a schema in which I drop the employees table and have employee_managers and employee_basics linked straight to the users table?
this is an polymorphic relationship. but if you want to be easy, you need to fix some things.
in the table employees
- user_id
- employable_id
- employable_type enum(Manager, Basic) # References to the target model
.... this last two are for the polymorphic relation, this is the nomenclature
in the basics and managers table you could delete the user_id field, but you need an id field as increments type
and now in the model Employee you need to make this function
public function employable(){
return $this->morphTo();
}
I hope this works :)
Related
I have a Users table that can store 8 different types of users. Depending on the user type, I have some other tables with the specific data set for it. So, I would like to use the ID from the Users table as a foreign key and primary key at the same time for those tables. But I am new at Laravel and I don't know how to do that to fit the conventions or, if it is not possible, how to do that when defining my models and one to one relations. Can someone help me? Thanks!
EDIT: Sorry, I think my explanation is not clear enough. Let's say I have 4 tables: users, user_types, customer_organzations, partners, and customers. I would like to use ID, that is PK of users, as a foreign key and primary key for tables customer_organizations, partners and customers, that have different information since they are different type of users in my application but all them login against users table. I don't care user_types table. I think I know how to deal with it.
You haven't given us much in terms of your table structure, so assuming you have a simple one-to-one relationship between a users table and a user_types table, the following would create the required relationship.
In your user_types table migration
$table->foreignId('user_id')->constrained();
The above will add your foreign key to the table and create the relationship back to the users table (this is done 'magically' using conventions so naming is important).
Then in your eloquent models, add the relationships between the models:
User.php
public function type()
{
return $this->hasOne(UserType::class);
}
UserType.php
public function user()
{
return $this->belongsTo(User::class);
}
I cannot find a solution, likely to how I am phrasing the question. I have a model called Invoice and it has the following relationship:
public function manifests(){
return $this->morphedByMany(carrier_manifest::class, 'invoiceable')->withPivot(['amount','rate_id','notes']);
}
As you can see, in the pivot, I have a table called rate_id. I would like to be able to add a relationship to another model based on the value of the rate_id (the model just being called ChargeRates). Is there a way I can do this in order to access a field in the ChargeRates model called label?
You'd want to actually implement the pivot table as a model if it has relationships and functionality on its own.
From a database concern, a many to many relationship between Table A and Table B is really just a one-to-many relationship between Table A and the pivot table and a one-to-many relationship between Table B and the pivot table.
Therefore, implementing your relationships with a pivot model using hasMany or morphMany is a way for you to accomplish what you're after.
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.
Let's consider a simple scenario of 'Company' and 'Employee' models.
A company has many employees. Now, when I map this relationship in Laravel, what is the correct approach from the following?
Approach 1:
Employee belongsTo() Company and Company hasMany() Employee
Approach 2:
Company belongsToMany() Employee and Employee hasOne() Company
Basically, what is the difference between belongsTo()-hasMany() and belongsToMany()-hasOne()?
There are three different approaches, in your question you're mixing them up a little. I'll go through all of them.
Many-to-many
A many-to-many relationship would mean, in your example, that a company can have multiple employees and that an employee can work for multiple companies.
So when you're using the belongsToMany() method on a relation, that implies you have a pivot table. Laravel by default assumes that this table is named after both other tables, e.g. company_employee in the example. Both the Company model and the Employee model would then have belongsToMany() relations.
Many-to-one
However, using hasMany() means that it's a one-to-many relationship. If we look at the example again, a company might have many employees but each employee would only be able to be employed by one company.
In the models, that means the Company would have a hasMany() method in its relationship declaration, while the Employee would have a belongsTo() method.
One-to-one
Finally, hasOne() means that it's a one-to-one relationship. What it would mean in your example is that each company may only have one employee. Since the inverse of hasOne() is also belongsTo(), in this scenario, too, every employee could be employed by only one company.
The Company model would then have a hasOne() relationship method, with the Employee having a belongsTo() method.
In practice, you almost always want to construct a database that is as close to reality in its representation as possible. What relationships you use depends on what your case looks like. In the example, I would guess that you want a many-to-one approach, with a foreign key on the employees table, that references the id on the companies table. But ultimately, that's up to you. Hope that helped. :)
In my database schema, I have multiple tables that hold generic data for objects, for instance I have a user table and a user_data, post table and post_data, and so. these *_data tables all hold a foreign key to the object and a pair of key-value. now in my laravel models I would like to have a single data models for these tables (rather than a model for every single one) and represent the has_many relation in a dynamic way where somehow I can define the table name according to the parent model. I think the parent model would have something like:
return $this->hasMany('data');
but I don't know how to express the inverse relation nor how to tell laravel which *_data table to use. so my question is, is it possible? and if so, how?
You have two options.
Either create a model for each data_* table and use the relation as stated with $this->hasMany('data'); and $this->belongsTo('User'); in the data table and the user table.
Or you can use Polymorphic relations, I personally prefer the polymorphic relations solution, more neat.