I have just started using Laravel. I have not used Laravel Eloquent before. So I am directly using it on graph database using NeoEloquent.
I know I can create relationship using hasMany() and attach() methods. But I want to create relationship only once. Has anybody used NeoEloquent for creating Unique Relationship.
You may use the hasOne()relationship instead of hasMany() which will ensure that only one relationship of the specified type exists for the model.
Related
In Laravel it is possible to use the hasMany() and belongsTo() methods in the Model to specify the relation between tables. This for one-to-many relations.
However in the migration files, this relation is also specified for the database by the
$table->foreign('userId')->references('id')->on('users')
Why does it to be specified double in Laravel?
Why does Laravel doesn't fetch the relationship from the database, and do we have to specify it double?
Laravel offers hasMany() and belongsTo() etc for quicker access to parent/child records between tables on the model level. For instance, you may access the child record with ->{attr}, which makes the child record as if an attribute of the parent record.
It also comes with other benefits, such as eager loading of child record by providing the relationship parameter into ->with() function.
In comparison, the usage of relation in migration files are to enforce relationship between tables on database level.
I am trying to create a script that could help me generate a GraphQL schema with all fields and relations exist in the models.
if I could get that, php-lighthouse would help me for the rest of the work.
There is no way to get all relations of a particular Eloquent model without the user specifying them in some way, such as an attribute on the model that holds all relation names, or type-hinting those methods returning a relation. See laravel-eloquent-to-graphql for an example.
You can however get all fields of a model (that are saved in the database) by inspecting its table.
If you're looking for a GraphQL generator, there are Laravel Bakery and laravel-eloquent-to-graphql. Laravel Bakery generates a GraphQL schema on-the-fly, while laravel-eloquent-to-graphql generates a GraphQL schema statically.
There is also Lighthouse-Utils, which can generate queries and mutations for already-defined types.
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
Laravel Version: 5.5
PHP Version: 7+
Database Driver & Version: mysql 5.7+
Scenario:
I have a SaaS application that has flexible database structure, so its fields are bound to change, especially given it has a Json field (for any extra database structure to be created from client side of the application), including relationship based fields. so Account Table can have dynamically created employee_id field, and thus the need to access relationships dynamically
Problem:
I need to EagerLoad models based on this dynamic relationship. If I had something like this:
// Account Model
public function employee(){
return $this->belongsTo(App\Employee);
}
it would be easy. But what I have is this:
public function modelBelongsTo(){
return $this->belongsTo($dynamicClassName, $dynamicForeignKey);
}
Now if I eager load this, I'll get Account Model instance with related Employee on key modelBelongsTo. This is how Eloquent Names based on the function of eagerload. But after this I cannot use this function again to eagerload a second model because it'll just overwrite results on modelBelongsTo key.
Possible Solution Directions:
1) Can I Somehow change laravel's process to use a name I provide?
or
2) Can I write functions on the fly to overcome this so I'll write employee function on the fly?
or
3) Worst Case Scenario: I iterate over all records to rename their keys individually because I am using a pagination, it wouldn't that big of a deal to loop over 10 records.
Us a morph relationship
define the various dynamic classnames say
Employee
Boss
Morph works by having the related key and the table name stored in the parent table, it means to relate them you have to use a join or an orm and you cant have foreign key constraint on it as it links to different tables.
then have your account have morphs where
we have
Account
as top class
then we have
EmployeeAccount, BossAccount
which have their relation to boss and employee
then in Account have morphto relation call it specificAccount()
to which in its child morphs have the morph relation to Account
then add it to $with so to eager load them so when fetching account you could simply do
$account ->specificAccount
to get its morph child. which is nullable
This is totally dynamic such that if you have other classes in future you can just add and add the morph relationship. This may be applied to any reflection or runtime evaluated and loaded classes/code though it is not advisable to do this, as you can always edit code to create new functionality without affecting previous.
I have some tables that are already created in the database. The migrations seem to require that you first destroy the table and then create it. From what I understand, the creation process generates a "model" at the same time as well as "getters" and "setters" for the fields.
The problem is that I have a database full of tables already. I would like to access the tables that have already been created using Laravel as an interface. Is there a way to generate a model, getters and setters for tables that already exist?
How can I best do this?
TIA
The default model generator doesn't create any getters or setters. All it does is create a basic model class with the correct model name based on the table name. You can create the models without actually creating the migration. The command is php artisan make:model ModelName.
So the answer to your question is no, there isn't any. You need to manually create each model and add the methods yourself. You might try your luck with some laravel package which might do this for you.
Note : Laravel Eloquent is an ActiveRecord implementation. You don't need any getters or setters to work with the table columns. Even a completely empty model with the correct name to match the table would be enough to start using Eloquent.