From 3dd626bf28a784e1a56e4082d29e5a81de00ef91 Mon Sep 17 00:00:00 2001
From: Kyle Filz <590498+Spice-King@users.noreply.github.com>
Date: Fri, 2 May 2025 15:53:42 -0500
Subject: [PATCH 1/5] Unify useForm's generic type across adaptors to new type
 in core

---
 packages/core/src/types.ts     | 19 ++++++++++++-------
 packages/react/src/useForm.ts  | 12 ++++++------
 packages/svelte/src/useForm.ts | 18 ++++++++++--------
 packages/vue3/src/useForm.ts   | 13 ++++++-------
 4 files changed, 34 insertions(+), 28 deletions(-)

diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index a301f06a6..8dd80e1e1 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -10,16 +10,21 @@ declare module 'axios' {
 export type Errors = Record<string, string>
 export type ErrorBag = Record<string, Errors>
 
+export type FormDataConvertibleValue = Blob | FormDataEntryValue | Date | boolean | number | null | undefined
 export type FormDataConvertible =
   | Array<FormDataConvertible>
   | { [key: string]: FormDataConvertible }
-  | Blob
-  | FormDataEntryValue
-  | Date
-  | boolean
-  | number
-  | null
-  | undefined
+  | FormDataConvertibleValue
+
+export type FormDataType<T extends object> = {
+  [K in keyof T]: T[K] extends FormDataConvertibleValue
+    ? T[K]
+    : T[K] extends (...args: unknown[]) => unknown
+      ? never
+      : T[K] extends object | Array<unknown>
+        ? FormDataType<T[K]>
+        : never
+}
 
 export type FormDataKeys<T extends Record<any, any>> = T extends T
   ? keyof T extends infer Key extends Extract<keyof T, string>
diff --git a/packages/react/src/useForm.ts b/packages/react/src/useForm.ts
index df60ec7f4..01bc317d7 100644
--- a/packages/react/src/useForm.ts
+++ b/packages/react/src/useForm.ts
@@ -1,6 +1,7 @@
 import {
   FormDataConvertible,
   FormDataKeys,
+  FormDataType,
   FormDataValues,
   Method,
   Progress,
@@ -14,11 +15,10 @@ import useRemember from './useRemember'
 
 type SetDataByObject<TForm> = (data: TForm) => void
 type SetDataByMethod<TForm> = (data: (previousData: TForm) => TForm) => void
-type SetDataByKeyValuePair<TForm extends Record<any, any>> = <K extends FormDataKeys<TForm>>(key: K, value: FormDataValues<TForm, K>) => void
-type FormDataType = Record<string, FormDataConvertible>
+type SetDataByKeyValuePair<TForm> = <K extends FormDataKeys<TForm>>(key: K, value: FormDataValues<TForm, K>) => void
 type FormOptions = Omit<VisitOptions, 'data'>
 
-export interface InertiaFormProps<TForm extends FormDataType> {
+export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   data: TForm
   isDirty: boolean
   errors: Partial<Record<FormDataKeys<TForm>, string>>
@@ -44,12 +44,12 @@ export interface InertiaFormProps<TForm extends FormDataType> {
   delete: (url: string, options?: FormOptions) => void
   cancel: () => void
 }
-export default function useForm<TForm extends FormDataType>(initialValues?: TForm): InertiaFormProps<TForm>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(initialValues?: TForm): InertiaFormProps<TForm>
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKey: string,
   initialValues?: TForm,
 ): InertiaFormProps<TForm>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKeyOrInitialValues?: string | TForm,
   maybeInitialValues?: TForm,
 ): InertiaFormProps<TForm> {
diff --git a/packages/svelte/src/useForm.ts b/packages/svelte/src/useForm.ts
index 86ac78c5a..ae31fc744 100644
--- a/packages/svelte/src/useForm.ts
+++ b/packages/svelte/src/useForm.ts
@@ -3,6 +3,7 @@ import type {
   Errors,
   FormDataConvertible,
   FormDataKeys,
+  FormDataType,
   Method,
   Page,
   PendingVisit,
@@ -16,10 +17,9 @@ import { cloneDeep, isEqual } from 'es-toolkit'
 import { get, has, set } from 'es-toolkit/compat'
 import { writable, type Writable } from 'svelte/store'
 
-type FormDataType = Record<string, FormDataConvertible>
 type FormOptions = Omit<VisitOptions, 'data'>
 
-export interface InertiaFormProps<TForm extends FormDataType> {
+export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   isDirty: boolean
   errors: Partial<Record<FormDataKeys<TForm>, string>>
   hasErrors: boolean
@@ -47,14 +47,16 @@ export interface InertiaFormProps<TForm extends FormDataType> {
   cancel(): void
 }
 
-export type InertiaForm<TForm extends FormDataType> = InertiaFormProps<TForm> & TForm
+export type InertiaForm<TForm extends FormDataType<TForm>> = InertiaFormProps<TForm> & TForm
 
-export default function useForm<TForm extends FormDataType>(data: TForm | (() => TForm)): Writable<InertiaForm<TForm>>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(
+  data: TForm | (() => TForm),
+): Writable<InertiaForm<TForm>>
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKey: string,
   data: TForm | (() => TForm),
 ): Writable<InertiaForm<TForm>>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKeyOrData: string | TForm | (() => TForm),
   maybeData?: TForm | (() => TForm),
 ): Writable<InertiaForm<TForm>> {
@@ -86,7 +88,7 @@ export default function useForm<TForm extends FormDataType>(
     data() {
       return Object.keys(data).reduce((carry, key) => {
         return set(carry, key, get(this, key))
-      }, {} as FormDataType) as TForm
+      }, {} as TForm)
     },
     transform(callback) {
       transform = callback
@@ -114,7 +116,7 @@ export default function useForm<TForm extends FormDataType>(
             .filter((key) => has(clonedData, key))
             .reduce((carry, key) => {
               return set(carry, key, get(clonedData, key))
-            }, {} as FormDataType) as TForm,
+            }, {} as TForm),
         )
       }
 
diff --git a/packages/vue3/src/useForm.ts b/packages/vue3/src/useForm.ts
index 6b4f56929..46fb5ea59 100644
--- a/packages/vue3/src/useForm.ts
+++ b/packages/vue3/src/useForm.ts
@@ -1,12 +1,11 @@
-import { FormDataConvertible, FormDataKeys, Method, Progress, router, VisitOptions } from '@inertiajs/core'
+import { FormDataKeys, FormDataType, Method, Progress, router, VisitOptions } from '@inertiajs/core'
 import { cloneDeep, isEqual } from 'es-toolkit'
 import { get, has, set } from 'es-toolkit/compat'
 import { reactive, watch } from 'vue'
 
-type FormDataType = Record<string, FormDataConvertible>
 type FormOptions = Omit<VisitOptions, 'data'>
 
-export interface InertiaFormProps<TForm extends FormDataType> {
+export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   isDirty: boolean
   errors: Partial<Record<FormDataKeys<TForm>, string>>
   hasErrors: boolean
@@ -32,14 +31,14 @@ export interface InertiaFormProps<TForm extends FormDataType> {
   cancel(): void
 }
 
-export type InertiaForm<TForm extends FormDataType> = TForm & InertiaFormProps<TForm>
+export type InertiaForm<TForm extends FormDataType<TForm>> = TForm & InertiaFormProps<TForm>
 
-export default function useForm<TForm extends FormDataType>(data: TForm | (() => TForm)): InertiaForm<TForm>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(data: TForm | (() => TForm)): InertiaForm<TForm>
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKey: string,
   data: TForm | (() => TForm),
 ): InertiaForm<TForm>
-export default function useForm<TForm extends FormDataType>(
+export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKeyOrData: string | TForm | (() => TForm),
   maybeData?: TForm | (() => TForm),
 ): InertiaForm<TForm> {

From 3cc76deafe3853b76e3fba91757ea2fa564e0157 Mon Sep 17 00:00:00 2001
From: Kyle Filz <590498+Spice-King@users.noreply.github.com>
Date: Fri, 2 May 2025 15:53:42 -0500
Subject: [PATCH 2/5] Update FormDataValues & FormDataKeys, make sure adaptors
 use it

---
 packages/core/src/types.ts     | 44 ++++++++++++++++++++++------------
 packages/react/src/useForm.ts  |  5 ++--
 packages/svelte/src/useForm.ts | 10 ++++----
 packages/vue3/src/useForm.ts   |  6 ++---
 4 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 8dd80e1e1..1a46a359b 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -26,25 +26,39 @@ export type FormDataType<T extends object> = {
         : never
 }
 
-export type FormDataKeys<T extends Record<any, any>> = T extends T
-  ? keyof T extends infer Key extends Extract<keyof T, string>
-    ? Key extends Key
-      ? T[Key] extends Record<any, any>
-        ? `${Key}.${FormDataKeys<T[Key]>}` | Key
-        : Key
+export type FormDataKeys<T> = T extends Function | FormDataConvertibleValue
+  ? never
+  : T extends Array<unknown>
+    ? number extends T['length']
+      ? `${number}` | `${number}.${FormDataKeys<T[number]>}`
+      :
+          | Extract<keyof T, `${number}`>
+          | {
+              [Key in Extract<keyof T, `${number}`>]: `${Key & string}.${FormDataKeys<T[Key & string]> & string}`
+            }[Extract<keyof T, `${number}`>]
+    :
+        | Extract<keyof T, string>
+        | {
+            [Key in Extract<keyof T, string>]: `${Key}.${FormDataKeys<T[Key]> & string}`
+          }[Extract<keyof T, string>]
+
+export type FormDataValues<T, K extends FormDataKeys<T>> = K extends `${infer P}.${infer Rest}`
+  ? T extends unknown[]
+    ? P extends `${infer I extends number}`
+      ? Rest extends FormDataKeys<T[I]>
+        ? FormDataValues<T[I], Rest>
+        : never
       : never
-    : never
-  : never
-
-export type FormDataValues<T extends Record<any, any>, K extends FormDataKeys<T>> = K extends `${infer P}.${infer Rest}`
-  ? P extends keyof T
-    ? Rest extends FormDataKeys<T[P]>
-      ? FormDataValues<T[P], Rest>
+    : P extends keyof T
+      ? Rest extends FormDataKeys<T[P]>
+        ? FormDataValues<T[P], Rest>
+        : never
       : never
-    : never
   : K extends keyof T
     ? T[K]
-    : never
+    : T extends unknown[]
+      ? T[K & number]
+      : never
 
 export type Method = 'get' | 'post' | 'put' | 'patch' | 'delete'
 
diff --git a/packages/react/src/useForm.ts b/packages/react/src/useForm.ts
index 01bc317d7..5105763fc 100644
--- a/packages/react/src/useForm.ts
+++ b/packages/react/src/useForm.ts
@@ -1,5 +1,4 @@
 import {
-  FormDataConvertible,
   FormDataKeys,
   FormDataType,
   FormDataValues,
@@ -30,7 +29,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   setData: SetDataByObject<TForm> & SetDataByMethod<TForm> & SetDataByKeyValuePair<TForm>
   transform: (callback: (data: TForm) => object) => void
   setDefaults(): void
-  setDefaults(field: FormDataKeys<TForm>, value: FormDataConvertible): void
+  setDefaults<T extends FormDataKeys<TForm>>(field: T, value: FormDataValues<TForm, T>): void
   setDefaults(fields: Partial<TForm>): void
   reset: (...fields: FormDataKeys<TForm>[]) => void
   clearErrors: (...fields: FormDataKeys<TForm>[]) => void
@@ -197,7 +196,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
   )
 
   const setDefaultsFunction = useCallback(
-    (fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: FormDataConvertible) => {
+    (fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: unknown) => {
       if (typeof fieldOrFields === 'undefined') {
         setDefaults(() => data)
       } else {
diff --git a/packages/svelte/src/useForm.ts b/packages/svelte/src/useForm.ts
index ae31fc744..9466344b5 100644
--- a/packages/svelte/src/useForm.ts
+++ b/packages/svelte/src/useForm.ts
@@ -1,9 +1,9 @@
 import type {
   ActiveVisit,
   Errors,
-  FormDataConvertible,
   FormDataKeys,
   FormDataType,
+  FormDataValues,
   Method,
   Page,
   PendingVisit,
@@ -28,12 +28,12 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   recentlySuccessful: boolean
   processing: boolean
   setStore(data: TForm): void
-  setStore(key: FormDataKeys<TForm>, value?: FormDataConvertible): void
+  setStore<T extends FormDataKeys<TForm>>(key: T, value: FormDataValues<TForm, T>): void
   data(): TForm
   transform(callback: (data: TForm) => object): this
   defaults(): this
   defaults(fields: Partial<TForm>): this
-  defaults(field?: FormDataKeys<TForm>, value?: FormDataConvertible): this
+  defaults<T extends FormDataKeys<TForm>>(field: T, value: FormDataValues<TForm, T>): this
   reset(...fields: FormDataKeys<TForm>[]): this
   clearErrors(...fields: FormDataKeys<TForm>[]): this
   setError(field: FormDataKeys<TForm>, value: string): this
@@ -80,7 +80,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
     wasSuccessful: false,
     recentlySuccessful: false,
     processing: false,
-    setStore(keyOrData, maybeValue = undefined) {
+    setStore(keyOrData: keyof InertiaFormProps<TForm> | FormDataKeys<TForm> | TForm, maybeValue = undefined) {
       store.update((store) => {
         return typeof keyOrData === 'string' ? set(store, keyOrData, maybeValue) : Object.assign(store, keyOrData)
       })
@@ -94,7 +94,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
       transform = callback
       return this
     },
-    defaults(fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: FormDataConvertible) {
+    defaults(fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: unknown) {
       if (typeof fieldOrFields === 'undefined') {
         defaults = cloneDeep(this.data())
       } else {
diff --git a/packages/vue3/src/useForm.ts b/packages/vue3/src/useForm.ts
index 46fb5ea59..11c2883f0 100644
--- a/packages/vue3/src/useForm.ts
+++ b/packages/vue3/src/useForm.ts
@@ -1,4 +1,4 @@
-import { FormDataKeys, FormDataType, Method, Progress, router, VisitOptions } from '@inertiajs/core'
+import { FormDataKeys, FormDataType, FormDataValues, Method, Progress, router, VisitOptions } from '@inertiajs/core'
 import { cloneDeep, isEqual } from 'es-toolkit'
 import { get, has, set } from 'es-toolkit/compat'
 import { reactive, watch } from 'vue'
@@ -16,7 +16,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   data(): TForm
   transform(callback: (data: TForm) => object): this
   defaults(): this
-  defaults(field: FormDataKeys<TForm>, value: FormDataConvertible): this
+  defaults<T extends FormDataKeys<TForm>>(field: T, value: FormDataValues<TForm, T>): this
   defaults(fields: Partial<TForm>): this
   reset(...fields: FormDataKeys<TForm>[]): this
   clearErrors(...fields: FormDataKeys<TForm>[]): this
@@ -71,7 +71,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
 
       return this
     },
-    defaults(fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: FormDataConvertible) {
+    defaults(fieldOrFields?: FormDataKeys<TForm> | Partial<TForm>, maybeValue?: unknown) {
       if (typeof data === 'function') {
         throw new Error('You cannot call `defaults()` when using a function to define your form data.')
       }

From 0300e75120894e40fec7851ec426b578d2d8e08a Mon Sep 17 00:00:00 2001
From: Kyle Filz <590498+Spice-King@users.noreply.github.com>
Date: Fri, 2 May 2025 15:53:42 -0500
Subject: [PATCH 3/5] Create error type for forms, apply to adaptors

---
 packages/core/src/types.ts     |  2 ++
 packages/react/src/useForm.ts  | 15 +++++++--------
 packages/svelte/src/useForm.ts |  7 ++++---
 packages/vue3/src/useForm.ts   | 15 ++++++++++++---
 4 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 1a46a359b..21dd66ff1 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -60,6 +60,8 @@ export type FormDataValues<T, K extends FormDataKeys<T>> = K extends `${infer P}
       ? T[K & number]
       : never
 
+export type FormDataError<T> = Partial<Record<FormDataKeys<T>, string>>
+
 export type Method = 'get' | 'post' | 'put' | 'patch' | 'delete'
 
 export type RequestPayload = Record<string, FormDataConvertible> | FormData
diff --git a/packages/react/src/useForm.ts b/packages/react/src/useForm.ts
index 5105763fc..ec8e5cead 100644
--- a/packages/react/src/useForm.ts
+++ b/packages/react/src/useForm.ts
@@ -1,4 +1,5 @@
 import {
+  FormDataError,
   FormDataKeys,
   FormDataType,
   FormDataValues,
@@ -20,7 +21,7 @@ type FormOptions = Omit<VisitOptions, 'data'>
 export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   data: TForm
   isDirty: boolean
-  errors: Partial<Record<FormDataKeys<TForm>, string>>
+  errors: FormDataError<TForm>
   hasErrors: boolean
   processing: boolean
   progress: Progress | null
@@ -34,7 +35,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   reset: (...fields: FormDataKeys<TForm>[]) => void
   clearErrors: (...fields: FormDataKeys<TForm>[]) => void
   setError(field: FormDataKeys<TForm>, value: string): void
-  setError(errors: Record<FormDataKeys<TForm>, string>): void
+  setError(errors: FormDataError<TForm>): void
   submit: (...args: [Method, string, FormOptions?] | [{ url: string; method: Method }, FormOptions?]) => void
   get: (url: string, options?: FormOptions) => void
   patch: (url: string, options?: FormOptions) => void
@@ -61,8 +62,8 @@ export default function useForm<TForm extends FormDataType<TForm>>(
   const recentlySuccessfulTimeoutId = useRef(null)
   const [data, setData] = rememberKey ? useRemember(defaults, `${rememberKey}:data`) : useState(defaults)
   const [errors, setErrors] = rememberKey
-    ? useRemember({} as Partial<Record<FormDataKeys<TForm>, string>>, `${rememberKey}:errors`)
-    : useState({} as Partial<Record<FormDataKeys<TForm>, string>>)
+    ? useRemember({} as FormDataError<TForm>, `${rememberKey}:errors`)
+    : useState({} as FormDataError<TForm>)
   const [hasErrors, setHasErrors] = useState(false)
   const [processing, setProcessing] = useState(false)
   const [progress, setProgress] = useState(null)
@@ -231,13 +232,11 @@ export default function useForm<TForm extends FormDataType<TForm>>(
   )
 
   const setError = useCallback(
-    (fieldOrFields: FormDataKeys<TForm> | Record<FormDataKeys<TForm>, string>, maybeValue?: string) => {
+    (fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: string) => {
       setErrors((errors) => {
         const newErrors = {
           ...errors,
-          ...(typeof fieldOrFields === 'string'
-            ? { [fieldOrFields]: maybeValue }
-            : (fieldOrFields as Record<FormDataKeys<TForm>, string>)),
+          ...(typeof fieldOrFields === 'string' ? { [fieldOrFields]: maybeValue } : fieldOrFields),
         }
         setHasErrors(Object.keys(newErrors).length > 0)
         return newErrors
diff --git a/packages/svelte/src/useForm.ts b/packages/svelte/src/useForm.ts
index 9466344b5..c13365225 100644
--- a/packages/svelte/src/useForm.ts
+++ b/packages/svelte/src/useForm.ts
@@ -1,6 +1,7 @@
 import type {
   ActiveVisit,
   Errors,
+  FormDataError,
   FormDataKeys,
   FormDataType,
   FormDataValues,
@@ -21,7 +22,7 @@ type FormOptions = Omit<VisitOptions, 'data'>
 
 export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   isDirty: boolean
-  errors: Partial<Record<FormDataKeys<TForm>, string>>
+  errors: FormDataError<TForm>
   hasErrors: boolean
   progress: Progress | null
   wasSuccessful: boolean
@@ -37,7 +38,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   reset(...fields: FormDataKeys<TForm>[]): this
   clearErrors(...fields: FormDataKeys<TForm>[]): this
   setError(field: FormDataKeys<TForm>, value: string): this
-  setError(errors: Errors): this
+  setError(errors: FormDataError<TForm>): this
   submit: (...args: [Method, string, FormOptions?] | [{ url: string; method: Method }, FormOptions?]) => void
   get(url: string, options?: FormOptions): void
   post(url: string, options?: FormOptions): void
@@ -122,7 +123,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
 
       return this
     },
-    setError(fieldOrFields: FormDataKeys<TForm> | Errors, maybeValue?: string) {
+    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: string) {
       this.setStore('errors', {
         ...this.errors,
         ...((typeof fieldOrFields === 'string' ? { [fieldOrFields]: maybeValue } : fieldOrFields) as Errors),
diff --git a/packages/vue3/src/useForm.ts b/packages/vue3/src/useForm.ts
index 11c2883f0..65dedaac4 100644
--- a/packages/vue3/src/useForm.ts
+++ b/packages/vue3/src/useForm.ts
@@ -1,4 +1,13 @@
-import { FormDataKeys, FormDataType, FormDataValues, Method, Progress, router, VisitOptions } from '@inertiajs/core'
+import {
+  FormDataError,
+  FormDataKeys,
+  FormDataType,
+  FormDataValues,
+  Method,
+  Progress,
+  router,
+  VisitOptions,
+} from '@inertiajs/core'
 import { cloneDeep, isEqual } from 'es-toolkit'
 import { get, has, set } from 'es-toolkit/compat'
 import { reactive, watch } from 'vue'
@@ -7,7 +16,7 @@ type FormOptions = Omit<VisitOptions, 'data'>
 
 export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   isDirty: boolean
-  errors: Partial<Record<FormDataKeys<TForm>, string>>
+  errors: FormDataError<TForm>
   hasErrors: boolean
   processing: boolean
   progress: Progress | null
@@ -105,7 +114,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
 
       return this
     },
-    setError(fieldOrFields: FormDataKeys<TForm> | Record<FormDataKeys<TForm>, string>, maybeValue?: string) {
+    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: string) {
       Object.assign(this.errors, typeof fieldOrFields === 'string' ? { [fieldOrFields]: maybeValue } : fieldOrFields)
 
       this.hasErrors = Object.keys(this.errors).length > 0

From 42fbe8c1d0527f39eb5bcb3728dd06930de8ae70 Mon Sep 17 00:00:00 2001
From: Kyle Filz <590498+Spice-King@users.noreply.github.com>
Date: Tue, 6 May 2025 15:35:13 -0500
Subject: [PATCH 4/5] Add ability to globally override error type for Pages and
 Forms

This will allow backends to send an array of strings and have the front end have correct types.
---
 packages/core/src/types.ts     | 27 +++++++++++++++++++++++++--
 packages/react/src/useForm.ts  |  3 ++-
 packages/svelte/src/useForm.ts |  5 +++--
 packages/vue3/src/useForm.ts   |  7 ++++---
 4 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/packages/core/src/types.ts b/packages/core/src/types.ts
index 21dd66ff1..741cdcc2a 100644
--- a/packages/core/src/types.ts
+++ b/packages/core/src/types.ts
@@ -7,7 +7,30 @@ declare module 'axios' {
   }
 }
 
-export type Errors = Record<string, string>
+export type DefaultInertiaConfig = {
+  errorValueType: string
+}
+/** 
+ * Designed to allow overriding of some core types using TypeScript
+ * interface declaration merging.
+ * 
+ * @see {@link DefaultInertiaConfig} for keys to override
+ * @example
+ * ```ts
+ * declare module '@inertiajs/core' {
+ *   export interface InertiaConfig {
+ *     errorValueType: string[]
+ *   }
+ * }
+ * ```
+ */
+export interface InertiaConfig {}
+export type InertiaConfigFor<Key extends keyof DefaultInertiaConfig> = Key extends keyof InertiaConfig
+  ? InertiaConfig[Key]
+  : DefaultInertiaConfig[Key]
+export type ErrorValue = InertiaConfigFor<'errorValueType'>
+
+export type Errors = Record<string, ErrorValue>
 export type ErrorBag = Record<string, Errors>
 
 export type FormDataConvertibleValue = Blob | FormDataEntryValue | Date | boolean | number | null | undefined
@@ -60,7 +83,7 @@ export type FormDataValues<T, K extends FormDataKeys<T>> = K extends `${infer P}
       ? T[K & number]
       : never
 
-export type FormDataError<T> = Partial<Record<FormDataKeys<T>, string>>
+export type FormDataError<T> = Partial<Record<FormDataKeys<T>, ErrorValue>>
 
 export type Method = 'get' | 'post' | 'put' | 'patch' | 'delete'
 
diff --git a/packages/react/src/useForm.ts b/packages/react/src/useForm.ts
index ec8e5cead..250b2a71a 100644
--- a/packages/react/src/useForm.ts
+++ b/packages/react/src/useForm.ts
@@ -1,4 +1,5 @@
 import {
+  ErrorValue,
   FormDataError,
   FormDataKeys,
   FormDataType,
@@ -34,7 +35,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   setDefaults(fields: Partial<TForm>): void
   reset: (...fields: FormDataKeys<TForm>[]) => void
   clearErrors: (...fields: FormDataKeys<TForm>[]) => void
-  setError(field: FormDataKeys<TForm>, value: string): void
+  setError(field: FormDataKeys<TForm>, value: ErrorValue): void
   setError(errors: FormDataError<TForm>): void
   submit: (...args: [Method, string, FormOptions?] | [{ url: string; method: Method }, FormOptions?]) => void
   get: (url: string, options?: FormOptions) => void
diff --git a/packages/svelte/src/useForm.ts b/packages/svelte/src/useForm.ts
index c13365225..a70735c77 100644
--- a/packages/svelte/src/useForm.ts
+++ b/packages/svelte/src/useForm.ts
@@ -1,6 +1,7 @@
 import type {
   ActiveVisit,
   Errors,
+  ErrorValue,
   FormDataError,
   FormDataKeys,
   FormDataType,
@@ -37,7 +38,7 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   defaults<T extends FormDataKeys<TForm>>(field: T, value: FormDataValues<TForm, T>): this
   reset(...fields: FormDataKeys<TForm>[]): this
   clearErrors(...fields: FormDataKeys<TForm>[]): this
-  setError(field: FormDataKeys<TForm>, value: string): this
+  setError(field: FormDataKeys<TForm>, value: ErrorValue): this
   setError(errors: FormDataError<TForm>): this
   submit: (...args: [Method, string, FormOptions?] | [{ url: string; method: Method }, FormOptions?]) => void
   get(url: string, options?: FormOptions): void
@@ -123,7 +124,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
 
       return this
     },
-    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: string) {
+    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: ErrorValue) {
       this.setStore('errors', {
         ...this.errors,
         ...((typeof fieldOrFields === 'string' ? { [fieldOrFields]: maybeValue } : fieldOrFields) as Errors),
diff --git a/packages/vue3/src/useForm.ts b/packages/vue3/src/useForm.ts
index 65dedaac4..1c2844361 100644
--- a/packages/vue3/src/useForm.ts
+++ b/packages/vue3/src/useForm.ts
@@ -1,4 +1,5 @@
 import {
+  ErrorValue,
   FormDataError,
   FormDataKeys,
   FormDataType,
@@ -29,8 +30,8 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   defaults(fields: Partial<TForm>): this
   reset(...fields: FormDataKeys<TForm>[]): this
   clearErrors(...fields: FormDataKeys<TForm>[]): this
-  setError(field: FormDataKeys<TForm>, value: string): this
-  setError(errors: Record<FormDataKeys<TForm>, string>): this
+  setError(field: FormDataKeys<TForm>, value: ErrorValue): this
+  setError(errors: Record<FormDataKeys<TForm>, ErrorValue>): this
   submit: (...args: [Method, string, FormOptions?] | [{ url: string; method: Method }, FormOptions?]) => void
   get(url: string, options?: FormOptions): void
   post(url: string, options?: FormOptions): void
@@ -114,7 +115,7 @@ export default function useForm<TForm extends FormDataType<TForm>>(
 
       return this
     },
-    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: string) {
+    setError(fieldOrFields: FormDataKeys<TForm> | FormDataError<TForm>, maybeValue?: ErrorValue) {
       Object.assign(this.errors, typeof fieldOrFields === 'string' ? { [fieldOrFields]: maybeValue } : fieldOrFields)
 
       this.hasErrors = Object.keys(this.errors).length > 0

From 70d34ad8d41e57eb08cc12da2fdf2962a89cbac4 Mon Sep 17 00:00:00 2001
From: Kyle Filz <590498+Spice-King@users.noreply.github.com>
Date: Thu, 17 Jul 2025 12:34:56 -0500
Subject: [PATCH 5/5] Fix React useForm to explicitly accept a function for
 initial value

---
 packages/react/src/useForm.ts | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/packages/react/src/useForm.ts b/packages/react/src/useForm.ts
index 80838cbb0..6f5d94b44 100644
--- a/packages/react/src/useForm.ts
+++ b/packages/react/src/useForm.ts
@@ -48,14 +48,16 @@ export interface InertiaFormProps<TForm extends FormDataType<TForm>> {
   delete: (url: string, options?: FormOptions) => void
   cancel: () => void
 }
-export default function useForm<TForm extends FormDataType<TForm>>(initialValues?: TForm): InertiaFormProps<TForm>
+export default function useForm<TForm extends FormDataType<TForm>>(
+  initialValues?: TForm | (() => TForm),
+): InertiaFormProps<TForm>
 export default function useForm<TForm extends FormDataType<TForm>>(
   rememberKey: string,
-  initialValues?: TForm,
+  initialValues?: TForm | (() => TForm),
 ): InertiaFormProps<TForm>
 export default function useForm<TForm extends FormDataType<TForm>>(
-  rememberKeyOrInitialValues?: string | TForm,
-  maybeInitialValues?: TForm,
+  rememberKeyOrInitialValues?: string | TForm | (() => TForm),
+  maybeInitialValues?: TForm | (() => TForm),
 ): InertiaFormProps<TForm> {
   const isMounted = useRef(null)
   const rememberKey = typeof rememberKeyOrInitialValues === 'string' ? rememberKeyOrInitialValues : null