Relationship modelling problem

rubyonrails-talk
1

I have battled with this for ages and would love some guidance

I am building an app that has: Companies Products

A product belongs to a company and a company has many products and hence: this company is a supplier

A company has many products and hence is a client

Every-time I give all relationships in the models it breaks and I think its due to the fact that the logic is broken as the separation of weather I am calling for clients or suppliers is not there and the model as I see it is broken because of the ambiguity

My models look as follows:

Company has many products has many assignments has many products through assignments

Products belongs to company has many assignments has many companies through assignments

Assignments belongs to company belongs to product

What is the best way to implement this and what controller do I use to call what relationship and how do I separate the difference of calling clients or suppliers (both being companies)

I have been at this for ages and am at my bitter end in terms of trying to work it out myself

2

I think I am going to try this:

Create the model Company: name:string Create Client: company_id:integer Create Supplier: company_id:integer Create Product: name:string Create Clientship: company_id:integer, product_id:integer Create Suppliership: company_id:integer, product_id:integer

Company has many :clients has many suppliers has many supplierships has many products through supplierships

Client belongs to :company has many :clientships has many :products, through clientship

Supplier belongs to :company has many :supplierships has many :products through supplierships

Product has many supplierships has many companies through supplierships has many clientship has many companies through clientships

Suppliership belongs to company belongs to product

Clientship belongs to company belongs to product

Generate a Controller for Clients, Products and Supplier Then I can use: Company.supierships to get suppliers (company names) Company.clientships to get the clients (company names)

So I still have one place storing companies and they are then not split

I will let everyone know where I get to : if you have any pointers or if there is a better way of doing it let me know Polymorphic can be used as its used I think to draw relations to a model however in this case the model is based on a relationship: If it has a product issues as client or supplier.

3

I have battled with this for ages and would love some guidance

I am building an app that has:

Companies

Products

A product belongs to a company and a company has many products and

hence: this company is a supplier

A company has many products and hence is a client

Every-time I give all relationships in the models it breaks and I think

its due to the fact that the logic is broken as the separation of

weather I am calling for clients or suppliers is not there and the model

as I see it is broken because of the ambiguity

My models look as follows:

Company

has many products

has many assignments

has many products through assignments

Products

belongs to company

has many assignments

has many companies through assignments

Assignments

belongs to company

belongs to product

What is the best way to implement this and what controller do I use to

call what relationship and how do I separate the difference of calling

clients or suppliers (both being companies)

I have been at this for ages and am at my bitter end in terms of trying

to work it out myself

I would highly recommend you try to work this out in a test-driven manner. That lets you start from simple to more complex and getting each piece working before you go further. That way, when you do hit the part where you start having problems, you have a laser focus on the problem and if it gets fixed (and if the fix breaks something else!)… I find that whatever the issue is, going about it this way makes it much easier to solve the problem.

That said, if you do not go this route, you should probably post your pertinent code and error messages concretely. Otherwise the person reading your message has to go and do the same background work in their head to reconstruct what you have already done.

4

I think I am going to try this:

Create the model Company: name:string

Create Client: company_id:integer

Create Supplier: company_id:integer

Create Product: name:string

Create Clientship: company_id:integer, product_id:integer

Create Suppliership: company_id:integer, product_id:integer

Company

has many :clients

has many suppliers

has many supplierships

has many products through supplierships

Client

belongs to :company

has many :clientships

has many :products, through clientship

Supplier

belongs to :company

has many :supplierships

has many :products through supplierships

Product

has many supplierships

has many companies through supplierships

has many clientship

has many companies through clientships

Suppliership belongs to company

belongs to product

Clientship belongs to company

belongs to product

PS… these (Suppliership and Clientship) I think are going in a strange direction. Object oriented should refer to actual things and these are like modifiers or adverbs? or something…

More than one model can have one or many objects, i.e.:

A Client can have many products A Supplier can have many products A Company can have many products

So you dont need ‘Suppliership’… you can ask for:

Company.Supplier.Products for example (this is pseudocode, but you get the picture).

I think you are over-analyzing.

5

Thanks for the reply David My app was working until I added the client model and relationships

I think you have given me good direction in terms of trying from the base up and testing using the console is something I need to master as it will then give me a good understanding of modeling and methods I can call based on the relationships

Thanks again