Add the ability to set a foreign key on a model to create relationships #296

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1. kettanaito commented on Dec 1, 2023

   

   kettanaito

   on Dec 1, 2023

   Last edited by kettanaito

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   Hi, @canrozanes. Thanks for raising this.

   Tell me, would the usage of transient + derivative properties work for you?

   const db = factory({
     user: {
       id: id(Number),
       // Create a transient "user.city" property.
       // It can be given initial value but it will never
       // be set on the user entities.
       city: transient(oneOf('city')),
       // Derive a public "user.cityId" foreign key
       // from the transient "user.city" one-of relationship.
       cityId: derivative(({ city }) => city.name),
     },
     city: {
       name: id(String),
     },
   })
   
   const user = db.user.create({
     id: 1,
     city: db.city.create({ name: 'London' }),
   })
   
   user.cityId // "London"
   user.city // undefined

   This is a non-existing API (yet).

   I'm tackling this precise use case in the Data rewrite and I could use your feedback.

   Why not use foreignKey()?

   The API you proposed implies that the key given as the value to the user_id property would be identifiable as foreign. But in the context of operations (create/update/etc), those key are taken from the existing extraneous models (like user), and will know nothing about post.userId having to be foreign.

   To put plainly, it becomes problematic to ensure the contract with this kind of API.
2. mswjs

   locked and limited conversation to collaborators on Dec 2, 2023
3. kettanaito

   converted this issue into a discussion #297 on Dec 2, 2023