Type Assertion for Optional Values in TypeScript

Question

Type Assertion for Optional Values in TypeScript

Just confirming the proper way to handle situations like this.

My current setup involves using Vue front-end with Typescript, sending data to an API via axios.

I've defined reactive objects as follows:

const payload = reactive({
  name: '',
  religion: undefined as string | undefined,
  gender: undefined as string | undefined
})

This is a basic example, but in cases where the religion and gender fields are not necessary unless explicitly provided when submitting the payload to the API, I have set them to default to undefined. This allows them to be filtered out before posting.

Am I handling this situation correctly?

Are there more efficient ways to approach this?

typescript vue.js rest axios undefined

Answer 1

Answer №1

One effective approach is to start by creating a type that accurately represents your data. You can utilize the foo?: SomeType syntax to indicate that a property is optional.

interface MyCoolThing {
    name: string,
    religion?: string
    gender?: string
}

Now, you can use this complete type to enforce the structure:

const payload = reactive({
  name: '',
  religion: undefined,
  gender: undefined,
} as MyCoolThing)

However, there's an even better way. The `reactive` function is generic and its type parameter corresponds to the type of its initial argument. Therefore, you can explicitly pass the type like so:

const payload = reactive<MyCoolThing>({
  name: '',
  religion: undefined,
  gender: undefined,
})

Check out the playground here

Answer 2

One effective approach is to start by creating a type that accurately represents your data. You can utilize the foo?: SomeType syntax to indicate that a property is optional.

interface MyCoolThing {
    name: string,
    religion?: string
    gender?: string
}

Now, you can use this complete type to enforce the structure:

const payload = reactive({
  name: '',
  religion: undefined,
  gender: undefined,
} as MyCoolThing)

However, there's an even better way. The `reactive` function is generic and its type parameter corresponds to the type of its initial argument. Therefore, you can explicitly pass the type like so:

const payload = reactive<MyCoolThing>({
  name: '',
  religion: undefined,
  gender: undefined,
})

Check out the playground here

Type Assertion for Optional Values in TypeScript

Answer №1

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