Theo's Typesafe Cult•17mo ago

Explicitly specifying an object in Prisma with its foreign relationships

I've set up my schema as an approximation of a directory structure: directories (ADirs) and documents (ADocs). Directories and documents can have a parent directory, which is a foreign key. I can write queries to retrieve directories and their children (childDirs, childDocs) without issue, but if I specify a directory as a state variable in a client component with useState, the type definition for ADir that I get from importing @prisma/clientdoes not have the children as a property. I've circumvented this issue by extending the type with my own interface, but I feel like it's a messy fix. Any tips? Thanks.

// helper for ADir object types that also need their children
// TODO: is there a better way to specify foreign objects in a type?
export interface ADirWithChilren extends ADir {
  childDirs: ADir[],
  childDocs: ADoc[]
}

// helper for ADir object types that also need their children
// TODO: is there a better way to specify foreign objects in a type?
export interface ADirWithChilren extends ADir {
  childDirs: ADir[],
  childDocs: ADoc[]
}

further reference: related libs are just next (using app router) and prisma. No trpc, zod, or superjson packages, but not against them if they are key to a good implementation.

Solution:

so then I'd get a type like this

export type Dir = Awaited<ReturnType<typeof getDir>>[number];

export type Dir = Awaited<ReturnType<typeof getDir>>[number];

...

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5 Replies

bakdaddy•17mo ago

I think it's because under the hood Prisma only makes the relations on its own level, so it's a little messy. I had a similar issue, what I did was I extracted the type from the query itself. Say you have a query

const getDir = async () => {
const dir = await prisma.adir.findMany({
include: {
childDirs: true,
childDocs: true
}
})
return dir
}

const getDir = async () => {
const dir = await prisma.adir.findMany({
include: {
childDirs: true,
childDocs: true
}
})
return dir
}

Solution

bakdaddy•17mo ago

so then I'd get a type like this

export type Dir = Awaited<ReturnType<typeof getDir>>[number];

export type Dir = Awaited<ReturnType<typeof getDir>>[number];

bakdaddy•17mo ago

it would get back the typings exactly as the return type of getDir()

[number]

[number]

it's for a singular item, as getDir returns an array of items

dumbitryOP•17mo ago

thanks for your help! It's working out well.

bakdaddy•17mo ago

No problems, happy to help

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Explicitly specifying an object in Prisma with its foreign relationships