I stumbled upon this problem today. My project has a few tables, for which I have created their dedicated Models. However, my project allows user to create dynamic tables.
How do I create relationships or models for/between these dynamically generated tables?
I would not recommend to create Eloquent Models on dynamically generated tables, because Eloquent Models are here to help developers with already created database tables (features like relationships, scopes, attributes casting are usually defined for existing database tables).
What would be my recommendation? Use the Query Builder instead. You will have almost the same functionalities of Eloquent Models, except without model.
Instead of having something like:
DynTable::where('foo', 123)
->where('bar', 456)
->first();
You will have the following:
DB::table('dyn_table')
->where('foo', 123)
->where('bar', 456)
->first();
Basically, the same. But, with the benefit that you can specify any table name to the Query Builder, but you can't change the table name to an Eloquent Model (in a running script).
Related
How to add multiple tables in one model without creating new model.
Is this standard practice to use same in laravel-lumen.
Or should I create 50 models to work on 50 tables.
You can't use multiple table in one model. Each model is written for a specific table.
https://laravel.com/docs/5.7/eloquent#introduction
Laravel uses Eloquent Object Relational Mapper. So each model is like a class representation having methods to do query underneath.
You have to create 50 models if you have 50 tables, or at-least for the tables you are using in your application. TO save time, go for plugins like this which would generate eloquent models based on your database structure. Also check another plugin if it helps.
It's not possible.
Each table should have their own model. But it isn't necessary all the times to make a model for each table. Investing some time on making model will help a lot in future work.
I have a doubt about eloquent, it should be a very basic doubt but Im not understanding.
For example, if we build a db diagram in mysql workbench or something like that, then if we want to create the same shema in laravel we need to add in the migrations the necessary id´s right?
The eloquent relationships (hasMany, belongsTo, etc) are just methods to fetch the info that is necessary in some context but the database schema, the relationships are set with the ids in the migrations right? The relationships (hasMany, belongsTo, etc) are not mandatory to build the database schema?
The migration would define the foreign keys that form the relationships described by hasMany, belongsTo, etc.
A seeder would need to do as you suggest and get the id for the row in the associated table so it can be populated in the foreign key column.
You can, of course, do some seeding in your migrations, but that should be done under very clear and limited circumstance.
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've just started using Laravel and I'm coming from a different system using an existing database. In this system there are 2 users table, one stock with the CMS and one custom one.
I want to create an Eloquent model which retrieves data from both tables into one model. I know I can use the following to create a relationship.
$this->hasOne('App\SecondUser', 'id', 'id);
But this results in 2 sql queries, and I want to join results from 2 tables before returning the model, in one join statement. How do I do this?
That might be a bit more complicated that you would expect.
First of all you have to use \DB facade to join the two collections(arrays) and then recreate the Eloquent collection from these arrays using Collection's make method.
More info about the Collection class here
An easier way might be to join them using standard laravel relationships and user something like Model::user->with('relation')->get.
But this will still create 2 queries (still relatively fast).
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.