I have a table customers with the fields id, name and so on.
One table doctors with the fields id, name.
Then there is one table subject_areas which has all subject areas which a doctor can have. The fields are id, text.
So, each doctor can have multiple subject areas. There is one pivot table doctor_subject which is a belongsToMany relation.
Here is my problem: A customer can have multiple doctors, but only for a specific subject area. I tried it with a new table customer_doctor with the fields id, customer_id and doctor_subject_id. But how do i map this in Eloquent?
Issue was in relation between tables. After chat clarification this came out as solution:
Html form is written in a way that customer first choose doctor, then depending on selection choose several of his available areas.
In that scenario customer needn't to be related to areas directly and should be related to areas only over relation with doctor.
Also as side note, if needed deeper relations, models on pivot tables could be created and used as well.
Related
Hello I am working with Laravel,
I have to create two simple models, let's say Stores and Books.
Stores can have one or multiple Books and Books can belong to many Stores.
Of course I will use a many to many relationship, with a pivot table.
Books the can have different prices depending the store.
I think a separate table can only complicate things, in my mind the pivot table associating books and stores should have a price column, but pivot tables only contains store_id and book_id.
Should I create a book_prices and associate it with books and to stores? What is the best approach?
You are free and able to set other attributes on your pivot table. You can read more about it in the docs.
https://laravel.com/docs/9.x/eloquent-relationships#retrieving-intermediate-table-columns
You have to define the relationship accordingly, the following should clarify how this works. In this example you use the many-to-many relationship and add the price column to every retrieved pivot model.
public function books()
{
return $this->belongsToMany(Book::class)
->withPivot('price')
}
For example, you are able to access the pivot column in a loop like this
foreach ($shop->books as $book)
{
echo $book->pivot->price;
}
You can define additional columns for your pivot table in the migration for the pivot table, and then when defining the relationship use withPivot to define the additional columns so they come through in the model:
return $this->belongsToMany(Book::class)->withPivot('price');
(Adapted from the Laravel documentation, see https://laravel.com/docs/9.x/eloquent-relationships#retrieving-intermediate-table-columns)
Depends on the complexity of your case, but yes, you have two options for it. Let's say that the pivot table is called as book_store:
Directly adds price column to book_store. This is obviously the simpler option. The drawbacks are:
The history of the price changes isn't logged. You'll have to create another table for logging if you want to keep this history information.
Changes made to price will directly change the price of the related book_store record. Meaning that a price is being updated "live" e.g users cannot update the price now but "publish" it some time later just like this example in the doc.
Create a new, different table to store the price. This may seems relatively more complex, but it may also be more future-proof.
Basically, you get 2 things that you miss in the first option above.
Don't think too much about book_store being a pivot table. One way to see it is like this: book_store IS a pivot table from books and stores tables viewpoints, but it's also just a normal SQL table which could relate to any other tables using any kind of relationships.
If you want to implement this, make sure to create a primary-key in the book_store table.
Alast, it all depends on what you need. Feel free to ask if you need more insight about this. I hope this helps.
This is more of a best practices question. I am making a game where factions can upgrade their technology for their faction. So I have a faction table which stores the faction name and id and a tech_upgrades table which stores the possible tech upgrades along with their costs. Then I have another table which stores the progress each faction has made towards their tech upgrades which is the faction_tech_upgrades table. So there should be a row in faction_tech_upgrades for every combination of faction and tech_upgrade. This kind of looks like a pivot table with extra data similar to https://laravel.com/docs/9.x/eloquent-relationships#retrieving-intermediate-table-columns
My dilemma involves how to set up the eloquent relationships. My gut says to use option 1 but just wanted to make sure I'm not setting these up poorly. So any advice on best practices is appreciated. Here are the 2 options I think make sense.
Option 1:
Create a model for faction_tech_upgrades. Then set up a one to many relationship between factions and faction_tech_upgrades, and set up a one to many relationship between tech_upgrades and faction_tech_upgrades. The reasoning here is that the faction_tech_upgrades table is functioning as more than just a pivot table so maybe making a model for it makes sense, as it might be easier to work with in terms of updating and querying the table.
Option 2:
Set faction_tech_upgrades up a as a pivot table and use the above link to get the data from that table. And use https://laravel.com/docs/9.x/eloquent-relationships#updating-a-record-on-the-intermediate-table to update the table.
factions columns
id,
name,
color,
created_at,
updated_at
tech_upgrades columns
id,
name,
description,
class,
order,
type,
gold_cost,
iron_cost,
wood_cost,
emerald_cost,
pink_tourmaline_cost,
turquoise_cost,
created_at,
updated_at
faction_tech_upgrades columns
id,
faction_id,
tech_upgrade_id,
unlocked,
gold_contributed,
iron_contributed,
wood_contributed,
emerald_contributed,
pink_tourmaline_contributed,
turquoise_contributed,
created_at,
updated_at
Any advice or other options appreciated.
If you have more than 2-3 extra fields in a pivot table, its better to create an another model and make one to many relationship as you describe in option one. It will will be easy to insert and update data. But if you follow the Laravel pivot table naming convention you will get extra benefit for easy access of the data.
I am stuck in situation where I need relation between 3 different tables. My tables are companies, products and Roles. Companies can assign multiple Roles to multiple products. The problem is Companies do not have any relationship with products. Products are added through admin.
Currently I have made a table company_product_role with structure company_id, product_id and role_id, the problem is how to make eloquent relation for insertion and retrieval. Either I am doing it correct or there is simple solution for it?
Any help will be appreciated.
SQL Server 2012 MVC3 EF4.3.1 Code First project.
I have a Teacher and Student table with a one to many relationship. The Teacher’s tables Id will be used as the account number so its Id numbering needs to be separate from the Student’s. I would like to create a Person table (containing shared properties such as First, Last, Phone, Email) to reduce redundancy on the properties. Person will also have a one to many relationship to an Address table.
I’ve thought of trying a Table per Hierarchy model with Teacher and Student inheriting from Person but then the Id sets would not be separate and I would have to have a one to many relationship internally on the Person table. I could generate the ID’s through code but is an internal one to many doable or practical?
Another scenario would be to setup Person as a child table with a one to one between and Teacher and Person and a one to one between Student and Person but I’m not sure how or if it’s possible to have two separate one to one’s on a table.
Is there a practical way to do what I want or should I not worry about the redundancy and not use a Person table? If I went that route would it be possible to have two separate one to many relationships to an Address table (Teacher-Address and Student-Address)? Or for that matter a one to many (Teacher-Address, teacher may have an additional shipping address) and one to one (Student-Address)?
Thank you
Another way to do it is to have a one to one between a Person and a Role table. Teacher and Student are merely roles in this arrangement. A given Role can be fulfilled by many Person instances.
You could also do a Person table with an IsTeacher flag.
I can see two possibilities:
One: Go with your Student and Teacher inheriting from a base table of Person and not worry about the 'redundancy'. It's not a redundancy because your relating a Student and a Teacher not a Person to a Person and so in your database and DOM the Person table and Person class know nothing of the Teacher to Student relationship, it only knows that its a person. The teacher and student relationships are stored in there respective types, not the person type. Also, look at Table per Type instead of Table per Heiarchy. It's much cleaner and crisper looking in the database and you don't get all the information of each type in the heiarchy in one table.
Two: Create a table that specifically holds information that both Students and Teachers share and have that related to both the Student and Teacher table separately. You could call it something like "ContactInformation".
Being a teacher and being a student are roles of people, not types of people.
You should have a table for People, a table TeachCourse to say that a Person is the teacher of a course (which in some cases are multiple teachers), a table AssistCourse to say which persons are attending a class as a student. You might have people that teach a course and assist another course, and that wasn't properly modeled in your first version.
You can also create a ContactInformation or ShippingInformation table for People to specify all their data (Some people may have multiple phones, or emails to).
I want to know how to handle mysql tables created with constraints in joomla.
for a example,
theater_table
id , name, description, image, address, tel, fax ,email
theater_facility_table
id, theater_id, facility_id
facility_table
id, name, description, image
Facility table already filled with data and id is the primary key. When creating a theater I am adding facilities to it. I created facility and theater JTables.
Do I have to create theater_facility JTable too?
Using theater Model class how I insert data to theater_facility table. I know I can insert data after theater stored successfully creating and calling storeTheaterFacility() method where it contains insert query to save required information. But I feel it can't be a good method to do so. Please help me to solve this.
Depending on how you implemented the theater - facility relationship, you can handle insering new data in different parts of your code. I mean, if for example your JTable class (the one that loads theaters) is loading/saving the theater-facilities relationship too, then the same class should delete it.
May be you can take a look at other components (for example, com_content, which relates an article to a category, or K2, where you can have multiple tags related to multiple "items"(articles)), so you can take a look on how do these components handle these kind of relationships.
Another important point you shouldn't forget is to update your facility model / table to delete records from the relationship table upon facility deleting.
I hope it helped!