fix(react-form): removing array items (#1171)

docs/reference/classes/fieldapi.md

@@ -163,7 +163,7 @@ The current field state.
 getInfo(): FieldInfo<TParentData>
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1217](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1217)
+Defined in: [packages/form-core/src/FieldApi.ts:1222](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1222)
 
 Gets the field information object.
 
@@ -179,7 +179,7 @@ Gets the field information object.
 getMeta(): FieldMeta<TParentData, TName, TData, TOnMount, TOnChange, TOnChangeAsync, TOnBlur, TOnBlurAsync, TOnSubmit, TOnSubmitAsync, TFormOnMount, TFormOnChange, TFormOnChangeAsync, TFormOnBlur, TFormOnBlurAsync, TFormOnSubmit, TFormOnSubmitAsync>
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1185](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1185)
+Defined in: [packages/form-core/src/FieldApi.ts:1190](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1190)
 
 #### Returns
 
@@ -193,7 +193,7 @@ Defined in: [packages/form-core/src/FieldApi.ts:1185](https://github.com/TanStac
 getValue(): TData
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1167](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1167)
+Defined in: [packages/form-core/src/FieldApi.ts:1172](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1172)
 
 Gets the current field value.
 
@@ -213,7 +213,7 @@ Use `field.state.value` instead.
 handleBlur(): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1627](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1627)
+Defined in: [packages/form-core/src/FieldApi.ts:1632](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1632)
 
 Handles the blur event.
 
@@ -229,7 +229,7 @@ Handles the blur event.
 handleChange(updater): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1620](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1620)
+Defined in: [packages/form-core/src/FieldApi.ts:1625](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1625)
 
 Handles the change event.
 
@@ -254,7 +254,7 @@ insertValue(
    opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1237](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1237)
+Defined in: [packages/form-core/src/FieldApi.ts:1242](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1242)
 
 Inserts a value at the specified index, shifting the subsequent values to the right.
 
@@ -307,7 +307,7 @@ moveValue(
    opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1293](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1293)
+Defined in: [packages/form-core/src/FieldApi.ts:1298](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1298)
 
 Moves the value at the first specified index to the second specified index.
 
@@ -337,7 +337,7 @@ Moves the value at the first specified index to the second specified index.
 pushValue(value, opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1222](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1222)
+Defined in: [packages/form-core/src/FieldApi.ts:1227](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1227)
 
 Pushes a new value to the field.
 
@@ -363,7 +363,7 @@ Pushes a new value to the field.
 removeValue(index, opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1269](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1269)
+Defined in: [packages/form-core/src/FieldApi.ts:1274](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1274)
 
 Removes a value at the specified index.
 
@@ -392,7 +392,7 @@ replaceValue(
    opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1253](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1253)
+Defined in: [packages/form-core/src/FieldApi.ts:1258](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1258)
 
 Replaces a value at the specified index.
 
@@ -422,7 +422,7 @@ Replaces a value at the specified index.
 setErrorMap(errorMap): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1647](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1647)
+Defined in: [packages/form-core/src/FieldApi.ts:1652](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1652)
 
 Updates the field's errorMap
 
@@ -444,7 +444,7 @@ Updates the field's errorMap
 setMeta(updater): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1190](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1190)
+Defined in: [packages/form-core/src/FieldApi.ts:1195](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1195)
 
 Sets the field metadata.
 
@@ -466,7 +466,7 @@ Sets the field metadata.
 setValue(updater, options?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1174](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1174)
+Defined in: [packages/form-core/src/FieldApi.ts:1179](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1179)
 
 Sets the field value and run the `change` validator.
 
@@ -495,7 +495,7 @@ swapValues(
    opts?): void
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1281](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1281)
+Defined in: [packages/form-core/src/FieldApi.ts:1286](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1286)
 
 Swaps the values at the specified indices.
 
@@ -547,7 +547,7 @@ Updates the field instance with new options.
 validate(cause, opts?): unknown[] | Promise<unknown[]>
 ```
 
-Defined in: [packages/form-core/src/FieldApi.ts:1587](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1587)
+Defined in: [packages/form-core/src/FieldApi.ts:1592](https://github.com/TanStack/form/blob/main/packages/form-core/src/FieldApi.ts#L1592)
 
 Validates the field value.
 

packages/form-core/src/FieldApi.ts

@@ -1135,17 +1135,25 @@
       TParentSubmitMeta
     >,
   ) => {
-    // Default Value
+    this.options = opts as never
 
+    const nameHasChanged = this.name !== opts.name
+    this.name = opts.name
+
+    // Default Value
     if (this.state.value === undefined) {
       const formDefault = getBy(opts.form.options.defaultValues, opts.name)
 
-      if (opts.defaultValue !== undefined) {
-        this.setValue(opts.defaultValue as never, {
+      const defaultValue = opts.defaultValue ?? formDefault
+
+      // The name is dynamic in array fields. It changes when the user performs operations like removing or reordering.
+      // In this case, we don't want to force a default value if the store managed to find an existing value.
+      if (nameHasChanged) {
+        this.setValue((val) => val || defaultValue, {
           dontUpdateMeta: true,
         })
-      } else if (formDefault !== undefined) {
-        this.setValue(formDefault as never, {
+      } else if (defaultValue !== undefined) {
+        this.setValue(defaultValue as never, {
           dontUpdateMeta: true,
         })
       }
@@ -1155,9 +1163,6 @@
     if (this.form.getFieldMeta(this.name) === undefined) {
       this.setMeta(this.state.meta)
     }
-
-    this.options = opts as never
-    this.name = opts.name
   }
 
   /**

packages/react-form/tests/useField.test.tsx

@@ -1,6 +1,6 @@
 /* eslint-disable react-compiler/react-compiler */
 import { describe, expect, it, vi } from 'vitest'
-import { render, waitFor } from '@testing-library/react'
+import { render, waitFor, within } from '@testing-library/react'
 import { userEvent } from '@testing-library/user-event'
 import { StrictMode, useState } from 'react'
 import { useStore } from '@tanstack/react-store'
@@ -1070,6 +1070,101 @@ describe('useField', () => {
     expect(getByText(`["Test"]`)).toBeInTheDocument()
   })
 
+  it('should handle removing element from array', async () => {
+    type Person = {
+      name: string
+      id: number
+    }
+
+    const fakePeople = {
+      jack: {
+        id: 5,
+        name: 'Jack',
+      },
+      molly: {
+        id: 6,
+        name: 'Molly',
+      },
+      george: {
+        id: 7,
+        name: 'George',
+      },
+    } satisfies Record<string, Person>
+
+    function Comp() {
+      const form = useForm({
+        defaultValues: {
+          people: [fakePeople.jack, fakePeople.molly, fakePeople.george],
+        },
+      })
+
+      return (
+        <form.Field name="people" mode="array">
+          {(field) => {
+            return (
+              <div>
+                <div data-testid="container">
+                  {field.state.value.map((item, i) => {
+                    return (
+                      <form.Field key={item.id} name={`people[${i}].name`}>
+                        {(subField) => {
+                          return (
+                            <div>
+                              <label>
+                                <div>Name for person {i}</div>
+                                <span>{subField.state.value}</span>
+                                <input
+                                  name={subField.name}
+                                  value={subField.state.value}
+                                  onChange={(e) =>
+                                    subField.handleChange(e.target.value)
+                                  }
+                                />
+                              </label>
+                            </div>
+                          )
+                        }}
+                      </form.Field>
+                    )
+                  })}
+                </div>
+                <button onClick={() => field.removeValue(1)} type="button">
+                  Remove person
+                </button>
+              </div>
+            )
+          }}
+        </form.Field>
+      )
+    }
+
+    const { getByText, queryByText, getByTestId } = render(
+      <StrictMode>
+        <Comp />
+      </StrictMode>,
+    )
+
+    let exisingPeople: Person[] = [
+      fakePeople.jack,
+      fakePeople.molly,
+      fakePeople.george,
+    ]
+    exisingPeople.forEach((person) =>
+      expect(getByText(person.name)).toBeInTheDocument(),
+    )
+    const container = getByTestId('container')
+    expect(within(container).getAllByRole('textbox')).toHaveLength(3)
+
+    await user.click(getByText('Remove person'))
+
+    expect(within(container).getAllByRole('textbox')).toHaveLength(2)
+    exisingPeople = [fakePeople.jack, fakePeople.george]
+    exisingPeople.forEach((person) =>
+      expect(getByText(person.name)).toBeInTheDocument(),
+    )
+    expect(queryByText(fakePeople.molly.name)).not.toBeInTheDocument()
+  })
+
   it('should not rerender unrelated fields', async () => {
     const renderCount = {
       field1: 0,