Description:
My application is structured as follows:
Property has a Many-Many relationship with Manager, and a Unit has a One-Many relationship with a Property, i.e. A manager can manage multiple properties, one property can have multiple manager accounts and one property can have multiple units.
I would like to have a HasManyThrough relationship on the manager to get all his units, so ideally it would look something like: $manager->units instead of having through loop through each property and call $property->units on it. Is this possible with the current version of laravel?
Tables:
managers:
id
properties:
id
managers_properties:
manager_id
property_id
units:
id
property_id
Eloquent currently does not have methods for chained relations, other than the hasManyThrough, that is only applicable to 2 chained hasMany relations. You should create your own implementation to fetch the related resources. The simplest way is to define an accessor on the Manager model:
namespace App\Models;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;
use Illuminate\Support\Collection;
/**
* #property-read Collection|\App\Models\Property[] $properties
* #property-read Collection|\App\Models\Unit[] $units
*/
class Manager extends Model
{
public function properties(): BelongsToMany
{
return $this->belongsToMany(Property::class);
}
public function getUnitsAttribute(): Collection
{
return $this->properties
->pluck('units')
->flatten(1)
->unique('id')
->sortBy('id');
}
}
You should now be able to access the related units with $manager->units assuming $manager instanceof App\Models\Manager.
Note
Calling $manager->units does perform at most n + 1 database queries: 1 for fetching n related properties, and another n for fetching related units for each returned property. "At most" because the resources might have been loaded already because of previous calls to the accessor.
Note
Calling $manager->units returns you a Collection of Unit models, a format that's equivalent to what you'd get from the magic accessor of a to-many relationship method. However getUnitsAttribute() is not an actual relationship method (it does not return a relationship object), so it can not be treated as such, whereas Manager::properties() can be.
Related
I have the following table structure as shown in the diagram:
Briefly, it is composed of several many-to-many polymorphic relationships as described:
many resources can have many sources and the pivot table sourceables contains catalog_number and lot_number information to make each row in the pivot table unique. Many resources could also come from the same source or from different sources, differentiated by the catalog number and lot number on the pivot table.
many resources can also have many publications attached to it, through the publicationables table with notes on the pivot table
a resource's source could also be described in many publications.
My questions:
Since the resource's source is differentiated by the pivot table sourceables how should I save the relationship between the pivot rows of sourceables to the publications?
Can you have a custom intermediate table models between both sourceables and 'publicationables' to link to the publications?
How to retrieve a resource with all it's publications and also with the sources with all corresponding publications?
Here is my answer and I hope that I can bring some light to your problem. I already publish a GitHub repository with an example of all the code I write here. I add more information about how to replicate my scenario there.
The Database and The Relations
Here is my interpretation of the Database and its relations. You can check all the Migrations on the repository.
The Solution
Question 1:
How should I save the relationship between the pivot rows of sourceable to the publications?
Answer:
Before proceeding with the code example, I would like to explain some important concepts to understand. I'm going to use the expression tag to refer to the identifier or index Morph Relations used to relate models.
The way this works, it's by assigning the tag to any Model you want to add into a relation. Any model using these tags can be store in the Morph Pivot Table. Laravel uses the _"modelable"type column to filter the call on the relations storing the Model Name. You can "tag" your Model with a Relation creating a method into the Model that returns the morphToMany relation function.
For this specific case, here's how to proceed:
In your Resource Model, you have two methods, one related to the sourceable index and the other with the publicationable tag using morphToMany in return.
Here's how it's look the Resource Model (./app/Models/Resource.php):
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class Resource extends Model
{
use HasFactory;
protected $guarded = [];
public function publications()
{
return $this->morphToMany(Publication::class, 'publicationable')->withPivot('notes');
}
public function sources()
{
return $this->morphToMany(Source::class, 'sourceable')->withPivot(['catalog_number', 'lot_number']);
}
}
In your Publication Model, you have two methods, one related to the sourceable index and the other with the inverse relation with the Resource Method to the publicationable tag using morphedByMany in return.
Here's how it looks the Publication Model (./app/Models/Publication.php):
<?php
namespace App\Models;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;
class Publication extends Model
{
use HasFactory;
protected $guarded = [];
public function sources()
{
return $this->morphToMany(Source::class, 'sourceable')->withPivot(['catalog_number', 'lot_number']);
}
public function resources()
{
return $this->morphedByMany(Resource::class, 'publicationable');
}
}
With this, you can be able to accomplish your goal of relating Publications with Resources and Sources.
Question 2: Can you have an intermediate table between both sourceable and publicationable to link to the publications?
Answer:
No, you don't need to. You can use the sourceables table to accomplish this. You can always relate a Source with ANY model by creating the method that returns the morphToMany relation to the Source model. These what we do with Publications on Question 1.
Question 3: How to retrieve a resource with all its publications and the sources with all corresponding publications?
Answer:
I think Eloquent it's my favorite feature on the whole Laravel Framework. This the cherry on the cake with all we do on the Model definition.
If you check the Resource and Publication Model definition again, we add a withPivot() method with the related field we want to include on any call we do to the relation with eloquent. This method made it possible to read custom values from the Pivot table.
IMPORTANT: For this example, I'm implicitly adding the pivot values because I don't declare those columns as NULL on the migrations.
To relate (Store on the Pivot table) a publication with a resource using the relation, you just need to:
(Using artisan tinker)
Psy Shell v0.10.8 (PHP 8.0.6 — CLI) by Justin Hileman
>>> $publication = \App\Models\Publication::find(5)
>>> $resource = \App\Models\Resource::find(19)
>>> $resource->publications()->attach($publication, ["notes" => "Eureka!"]);
### Adding another Publication
>>> $publication = \App\Models\Publication::find(10)
>>> $resource->publications()->attach($publication, ["notes" => "Eureka 2!"]);
(Using a Controller)
use App\Models\Resource;
use App\Models\Publication;
...
$id_resource = 1; // This is the Resource Id you want to reach.
$id_publication = 10; // This is the Resource Id you want to reach.
$resource = Resource::find($id_resource);
$publication = Publication::find($id_publication);
$pivotData = [ "notes" => "Eureka!" ];
$resource->publications()->attach($publication, $pivotData);
To retrieve all publications from a resource, you just need to:
(Using artisan tinker)
Psy Shell v0.10.8 (PHP 8.0.6 — CLI) by Justin Hileman
>>> $resource = \App\Models\Publication::find(5)
>>> $resource->publications()->get();
Easy right? :) Eloquent POWER!
(Using a Controller)
use App\Models\Resource;
...
$id_resource = 1; // This is the Resource Id you want to reach.
$resource = Resource::find($id_resource);
$resource->publications()->get();
Just in case of any doubt, this is how you can store and retrieve from all the models:
(Using a Controller)
use App\Models\Publication;
use App\Models\Resource;
use App\Models\Source;
...
... Method ...
$id_publication = 1;
$id_resource = 1;
$id_source = 1;
$publication = Publication::find($id_resource);
$resource = Resource::find($id_resource);
$source = Source::find($id_resource);
$publicationPivotColumns = [
"notes" => "This is a note...",
];
$sourcePivotColumns = [
"catalog_number" => 100,
"lot_number" => 4903,
];
// Storing Data
// Attach (Store in the publicationables table) a Publication to a Resource
$resource->publications()->attach($publication, $publicationPivotColumns);
// Attach (Store in the sourceables table) a Source to a Resource
$resource->sources()->attach($source, $sourcePivotColumns);
// Attach (Store in the sourceables table) a Source to a Publication
$publication->sources()->attach($source, $sourcePivotColumns);
// Retraiving Data
// Get all Sources from a Resource
$resource->sources()->get();
// Get all Publications from a Resource
$resource->publications()->get();
// Get all Sources from a Publication
$publication->sources()->get();
I have 3 databases:
Routes:
id
name
Rates:
Id
Route_id
Car_id
Cars:
id
name
My model for routes
public function rates()
{
return $this->hasMany('App\Rate', 'route_id');
}
My model for rates
public function car() {
return $this->belongsTo('App\Car','car_id');
}
Now I need to access the car relation, but when I do
return $this->route->with('from','to','rates.car')->paginate(74);
I get null for the car relation
{"id":1,"from_id":1,"to_id":2,"distance":400,"created_at":null,"updated_at":null,"from":{"id":1,"name":"\u0410\u043a\u043a\u043e","created_at":null,"updated_at":null,"lat":32.93310000000000314912540488876402378082275390625,"long":35.0827000000000026602720026858150959014892578125},"to":{"id":2,"name":"\u0410\u0440\u0430\u0434","created_at":null,"updated_at":null,"lat":31.261399999999998300381776061840355396270751953125,"long":35.21490000000000009094947017729282379150390625},"rates":[{"id":1,"route_id":1,"car_id":1,"rate":1123,"night_rate":1391,"car":null},{"id":5551,"route_id":1,"car_id":2,"rate":1123,"night_rate":1391,"car":null},{"id":11101,"route_id":1,"car_id":3,"rate":1123,"night_rate":1391,"car":null},{"id":16651,"route_id":1,"car_id":4,"rate":1123,"night_rate":1391,"car":null},{"id":22201,"route_id":1,"car_id":5,"rate":1123,"night_rate":1391,"car":null},{"id":27751,"route_id":1,"car_id":6,"rate":1123,"night_rate":1391,"car":null},{"id":33301,"route_id":1,"car_id":7,"rate":1123,"night_rate":1391,"car":null},{"id":38851,"route_id":1,"car_id":8,"rate":1123,"night_rate":1391,"car":null}]},
From my understanding you are trying to access a Car model through a Route model.
A couple of things I noticed that should help you find a solution.
First off I think the inverse relation you are supposed to use the belongToMany() function instead.
public function car() {
return $this->belongsToMany('App\Car','Rates'); // Perhaps call the table something like routes_cars to more clearly define it's a pivot table
}
Next I see you are trying to use model functions within the context of $this(). I assume you are doing this in your model? That logic should be in a controller, that might cause some undesired results but I'm not entirely sure. Also it looks like your parameters are incorrect when using with(). You use the function name that you defined in belongsToMany()
App/Route::with('car')->paginate(74);
With the correct relationships setup you rarely need to worry about the pivot table. If you are going to add extra information in the pivot table there are laravel functions to help you do that in the documentation.
I have problems to build a relationship with eloquent.
I have two models created, Spielplan and Verein. In model Spielplan I have the fields Team_ID and Spiel_ID. In model Verein I have the field V_ID and Name. Now I need to join this two tables about Team_ID = V_ID.
This is my model
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Spielplan extends Model
{
protected $table = 'Spielplan';
public function vereinFunction(){
return $this->hasOne('App\Verein', 'V_ID');
}
}
And this is a function in my web route where I want to get Spiel_ID and Name.
Route::get('test', function(){
$spieleT = App\Spielplan::where('Spiel_ID', '=', 30)->get();
foreach($spieleT as $da){
echo $da->Spiel_ID;
echo $da->vereinFunction->Name;
}
});
The first echo works and I get back Spiel_ID but the second echo gives back ErrorException Trying to get property of non-object.
What is wrong with my code?
Try editing this line:
$spieleT = App\Spielplan::with('vereInFunction')->where('Spiel_ID', '=', 30)->get();.
The with() allows you to fetch the association at the time you use get(). After using get(), you're working with a collection, and can't query the database again.
Try specifying the model primary key as a third argument, because if not, Laravel will assume it is named id, which is not the case.
Allow me to suggest you something: I used to name the tables and fields like you do (in the days I use Codeigniter) but since I started using Laravel around three years ago, I follow Laravel convention (which is recommended, but not imposed). I now name the tables in lowercase, (snakecase) plural, table fields also snakecasm lowercase. Models singular, camelcase similar corresponding table, relation function names as related model, being singular if relation is to one, plural if to many, etc. The advantage of this is among other reflected in model relationship declaration, which is a lot simpler and easier to define.
For instance (only as demonstration of stated above),
tables (with relation one to many:
managers (primarykey: id, name, ......)
technicians (primary key: id, foreingkey: manager_id (related table name in singular plus underscore plus id), name, .....)
models:
Manager:
/* relationships */
public function technicians () // see name as related table, plural due to as many relationship)
{
return $this->hasMany(Technician::class); // as naming convention has followed, you don't need to specify any extra parameters;
}
Techician:
/* relationship */
public function manager() // named as related table, singular due to to one relationship
{
$this->belongsToOne(Manager::class); // again, as naming convention has followed, you don't need to specify any extra parameters;
}
Therefore you can do this:
$manager::find(1);
echo $manager->technicians->first()->name,
or
foreach ($manager->technicians as $technician) {
echo $technician->name;
}
as well as:
$technician->manager->name;
Remember, a proper model relationship definition will save a lot of headache along the way, like the one you have
Hope this help in anyway
I have been trying to get my head around these polymorphic relationships all day. I might be over complicating/thinking it but. Can Laravel handle inverse polymorphic relationships? I have a registration flow that can have two types of field Models- normal field and customField.
When I loop through all the fields available it could pull the attributes from either NormalField or CustomField.
<?php
foreach($registrationFlow->fields->get() as $field)
{
echo $field->name; // could be custom field or could be normal field
}
?>
My difficulty is that, the example given in the docs works if you want to assign a photo to either staff or orders, but i want to assign either a customField or a normalField to a registrationFlow
*Edit
If you follow the example for the polymorphic many to many relationship, The tag class contains posts and videos- while i would want just a simple fields() method that relates to customField or normalField dependent on the type
First of all, you should take a look at the updated docs for Laravel 5.1: https://laravel.com/docs/5.1/eloquent-relationships#polymorphic-relations.
I think the difficulty with the example they provide is that the relationship between Photo and Staff/Product are "has-a" relationships, whereas you are trying to model an "is-a" relationship. However, you can model "is-a" essentially the same way. Take a look at this article: http://richardbagshaw.co.uk/laravel-user-types-and-polymorphic-relationships/.
Basically, the strategy is to define a generic model (and a generic table), perhaps in your case Field, that relates to your RegistrationFlow. You then have two subtype models, NormalField and CustomField, that have one-to-one relationships with Field. (there's your "is-a"). Thus, RegistrationFlow is indirectly related to your field subtypes.
Polymorphism comes in when you want to access the specific subtypes:
class Field extends Model {
public function fieldable()
{
return $this->morphTo();
}
}
Your base field table should have fieldable_id and fieldable_type columns defined (see the Eloquent docs).
You can then add methods to NormalField and CustomField that let you access the base model (your "inverse relationship"):
class NormalField {
public function field()
{
return $this->morphOne('Field', 'fieldable');
}
}
class CustomField {
public function field()
{
return $this->morphOne('Field', 'fieldable');
}
}
Usage:
$field = Field::find(1);
// Gets the specific subtype
$fieldable = $field->fieldable;
I have a class Report which has a belongsToMany relation to Metric. Report also additionally has a belongsTo relation to Metric.
Normally, the model returned by the belongsTo relation is the same as one of the models in the belongsToMany relation. When this is true I'd like it to be the case that each of the two relations actually looks at the same object instance (this also saves an extra trip to the db).
So, in basic terms - is there a way to get one relation to check another first, to see if a model has already been loaded, and if so, point to that object rather than creating a new one.
I tried putting some code in the belongsTo relation method for Metric but I can't get round the fact it needs to return an instance of belongsTo, which needs various things passed as constructor arguments (ie. a query object), which aren't relevant in that case that the model has already been loaded in the belongsToMany relation.
I thought of ditching the belongsTo relation and adding data horizontally in the pivot table for the belongsToMany relation, but it isn't a many-to-many relation required so that seems a bit wrong.
Thanks!
Geoff
The idea here is to write a function which would check if a relationship is loaded and return that relationship, otherwise it will return the belongsToMany. This would go in your Report class. This is also for Laravel 5. If you have 4, just remove the namespaces from the model names.
public function metric()
{
return $this->belongsTo('App\Metric');
}
public function metrics()
{
return $this->belongsToMany('App\Metric');
}
public function getMetric()
{
if(array_key_exists('metric', $this->getRelations())) {
return $this->metric;
}
return $this->metrics()->first();
}
If you do decide to just go with a belongsToMany only, I'd suggest putting a unique key on your pivot table for both ID's to keep from getting any duplicates in the pivot table.