Infer Types

ZSA provides some helpful utility types that allow you to infer the input, return type, return data, and hot return type of a server action.

Infer Server Action Return Data

Use inferServerActionReturnData to infer the return data type of a server action. This will be the type of the data in the [data, error] tuple.

import { inferServerActionReturnData } from "zsa"

const myAction = createServerAction()
  .input(z.object({ num: z.number() }))
  .output(z.number())
  .handler(async ({ input }) => {
    return input.num + 1
  })

type MyActionReturnData = inferServerActionReturnData<typeof myAction>
//   ^? number

Infer Server Action Error

Use inferServerActionError to infer the error type of a server action. This will be the type of the error in the [data, error] tuple.

import { inferServerActionError } from "zsa"

const myAction = createServerAction()
  .input(z.object({ num: z.number() }))
  .output(z.number())
  .handler(async ({ input }) => {
    return input.num + 1
  })

type MyActionError = inferServerActionError<typeof myAction>
//   ^? TZSAError<z.ZodType<number>>

Infer Server Action Return Type

Use inferServerActionReturnType to infer the return type of a server action. This will be a tuple of [data, error].

import { inferServerActionReturnType } from "zsa"

const myAction = createServerAction()
  .input(z.object({ num: z.number() }))
  .output(z.number())
  .handler(async ({ input }) => {
    return input.num + 1
  })

type MyActionReturnType = inferServerActionReturnType<typeof myAction>
//   ^? [number, null] | [null, TZSAError]

Infer Server Action Return Type Hot

Use inferServerActionReturnTypeHot to infer the hot (unresolved) return type of a server action. This will be a tuple promise.

import { inferServerActionReturnTypeHot } from "zsa" 

const myAction = createServerAction()
  .input(z.object({ num: z.number() })) 
  .output(z.number())
  .handler(async ({ input }) => {
    return input.num + 1  
  })

type MyActionReturnTypeHot = inferServerActionReturnTypeHot<typeof myAction>  
//   ^? Promise<[number, null] | [null, TZSAError]>

Infer Server Action Input

Use inferServerActionInput to infer the input type of a server action.

import { inferServerActionInput } from "zsa"

const myAction = createServerAction()
  .input(z.object({ num: z.number() }))
  .handler(async ({ input }) => {
    return input.num + 1
  })  

type MyActionInput = inferServerActionInput<typeof myAction>
//   ^? { num: number }