Using existing values in model definition functions

[mauriceoc]

Hey folks,

Been using the data library for a couple of things and it's going great. Just encountered an issue though -

I have a model definition using faker like this:

user: {
        id: primaryKey(faker.datatype.uuid),
        firstName: faker.name.firstName,
        lastName: faker.name.lastName,
        email: faker.internet.exampleEmail
    }

This works fine, but I'd like the user's email to be generated with correct firstName and lastName, so something like this:

user: {
        id: primaryKey(faker.datatype.uuid),
        firstName: faker.name.firstName,
        lastName: faker.name.lastName,
        email: () => faker.internet.exampleEmail(??, ??)
    }

Could be my javascript needs polishing but not sure how I can get access to the existing firstName and lastName values within the email function! Any thoughts?

[mauriceoc]

Can see this question is up for discussion in this issue, so will follow that.

[kettanaito]

Update

Since v1.0, Data no longer provides any object modeling capabilities. You can use any Standard Schema-compliant library (Zod, ArkType, etc) to describe a schema where some properties are derived from other properties.

Here's an example of deriving the email field from the firstsName and lastName fields:

data/tests/create-derived-property.test.ts

Lines 5 to 16 in 471a1f6

	const users = new Collection({
	schema: z
	.object({
	firstName: z.string(),
	lastName: z.string(),
	email: z.email().optional(),
	})
	.transform((user) => {
	user.email = `${user.firstName.toLowerCase()}.${user.lastName.toLowerCase()}@email.com`
	return user
	}),
	})

You should do this on the schema level. This means that you should consult your schema library of choice on the exact APIs to achieve such derived values.