fix: deleteField inside of an array should now work

* Add basic tests for arrays

* Ran prettier

* Ran prettier

* Add new test for bug

* Fix bug regarding preserved values even if field is umounted

* Run prettier

* Update store subscription when removingFields

* Fix delete field

* Fix delete field

* Fix bug with deleteField inside an array

* Fix bug with deleteField inside an array

* Fix bug with deleteField inside an array

* Improve error

* Improve error

* Add tests for utils

* Add tests for utils

* chore: fix test errors, remove errant test utils

---------

Co-authored-by: Corbin Crutchley <git@crutchcorn.dev>

Author: Christian24

packages/form-core/src/FormApi.ts

@@ -1,6 +1,12 @@
 import { Store } from '@tanstack/store'
 import type { DeepKeys, DeepValue, Updater } from './utils'
-import { functionalUpdate, getBy, isNonEmptyArray, setBy } from './utils'
+import {
+  deleteBy,
+  functionalUpdate,
+  getBy,
+  isNonEmptyArray,
+  setBy,
+} from './utils'
 import type { FieldApi, FieldMeta, ValidationCause } from './FieldApi'
 import type { ValidationError, Validator } from './types'
 
@@ -553,8 +559,9 @@ export class FormApi<TFormData, ValidatorType> {
   deleteField = <TField extends DeepKeys<TFormData>>(field: TField) => {
     this.store.setState((prev) => {
       const newState = { ...prev }
-      delete newState.values[field as keyof TFormData]
+      newState.values = deleteBy(newState.values, field)
       delete newState.fieldMeta[field]
+
       return newState
     })
   }

packages/form-core/src/tests/FormApi.spec.ts

@@ -226,6 +226,63 @@ describe('form api', () => {
     expect(form.getFieldValue('names')).toStrictEqual(['one', 'three', 'two'])
   })
 
+  it('should handle fields inside an array', async () => {
+    interface Employee {
+      firstName: string
+    }
+    interface Form {
+      employees: Partial<Employee>[]
+    }
+
+    const form = new FormApi<Form, unknown>()
+
+    const field = new FieldApi({
+      form,
+      name: 'employees',
+      defaultValue: [],
+    })
+
+    field.mount()
+
+    const fieldInArray = new FieldApi({
+      form,
+      name: `employees.${0}.firstName`,
+      defaultValue: 'Darcy',
+    })
+    fieldInArray.mount()
+    expect(field.state.value.length).toBe(1)
+    expect(fieldInArray.getValue()).toBe('Darcy')
+  })
+
+  it('should handle deleting fields in an array', async () => {
+    interface Employee {
+      firstName: string
+    }
+    interface Form {
+      employees: Partial<Employee>[]
+    }
+
+    const form = new FormApi<Form, unknown>()
+
+    const field = new FieldApi({
+      form,
+      name: 'employees',
+      defaultValue: [],
+    })
+
+    field.mount()
+
+    const fieldInArray = new FieldApi({
+      form,
+      name: `employees.${0}.firstName`,
+      defaultValue: 'Darcy',
+    })
+    fieldInArray.mount()
+    form.deleteField(`employees.${0}.firstName`)
+    expect(field.state.value.length).toBe(1)
+    expect(Object.keys(field.state.value[0]!).length).toBe(0)
+  })
+
   it('should not wipe values when updating', () => {
     const form = new FormApi({
       defaultValues: {
@@ -500,7 +557,6 @@ describe('form api', () => {
 
     form.mount()
     field.mount()
-
     expect(form.state.errors.length).toBe(0)
     field.setValue('other', { touch: true })
     field.validate('blur')

packages/form-core/src/tests/utils.spec.ts

@@ -0,0 +1,73 @@
+import { describe, expect, it } from 'vitest'
+import { deleteBy, getBy, setBy } from '../utils'
+
+describe('getBy', () => {
+  const structure = {
+    name: 'Marc',
+    kids: [
+      { name: 'Stephen', age: 10 },
+      { name: 'Taylor', age: 15 },
+    ],
+    mother: {
+      name: 'Lisa',
+    },
+  }
+
+  it('should get subfields by path', () => {
+    expect(getBy(structure, 'name')).toBe(structure.name)
+    expect(getBy(structure, 'mother.name')).toBe(structure.mother.name)
+  })
+
+  it('should get array subfields by path', () => {
+    expect(getBy(structure, 'kids.0.name')).toBe(structure.kids[0]!.name)
+    expect(getBy(structure, 'kids.0.age')).toBe(structure.kids[0]!.age)
+  })
+})
+
+describe('setBy', () => {
+  const structure = {
+    name: 'Marc',
+    kids: [
+      { name: 'Stephen', age: 10 },
+      { name: 'Taylor', age: 15 },
+    ],
+    mother: {
+      name: 'Lisa',
+    },
+  }
+
+  it('should set subfields by path', () => {
+    expect(setBy(structure, 'name', 'Lisa').name).toBe('Lisa')
+    expect(setBy(structure, 'mother.name', 'Tina').mother.name).toBe('Tina')
+  })
+
+  it('should set array subfields by path', () => {
+    expect(setBy(structure, 'kids.0.name', 'Taylor').kids[0].name).toBe(
+      'Taylor',
+    )
+    expect(setBy(structure, 'kids.0.age', 20).kids[0].age).toBe(20)
+  })
+})
+
+describe('deleteBy', () => {
+  const structure = {
+    name: 'Marc',
+    kids: [
+      { name: 'Stephen', age: 10 },
+      { name: 'Taylor', age: 15 },
+    ],
+    mother: {
+      name: 'Lisa',
+    },
+  }
+
+  it('should delete subfields by path', () => {
+    expect(deleteBy(structure, 'name').name).not.toBeDefined()
+    expect(deleteBy(structure, 'mother.name').mother.name).not.toBeDefined()
+  })
+
+  it('should delete array subfields by path', () => {
+    expect(deleteBy(structure, 'kids.0.name').kids[0].name).not.toBeDefined()
+    expect(deleteBy(structure, 'kids.0.age').kids[0].age).not.toBeDefined()
+  })
+})

packages/form-core/src/utils.ts

@@ -17,8 +17,7 @@ export function functionalUpdate<TInput, TOutput = TInput>(
  * Get a value from an object using a path, including dot notation.
  */
 export function getBy(obj: any, path: any) {
-  const pathArray = makePathArray(path)
-  const pathObj = pathArray
+  const pathObj = makePathArray(path)
   return pathObj.reduce((current: any, pathPart: any) => {
     if (typeof current !== 'undefined') {
       return current[pathPart]
@@ -52,22 +51,59 @@ export function setBy(obj: any, _path: any, updater: Updater<any>) {
       }
     }
 
+    if (Array.isArray(parent) && key !== undefined) {
+      const prefix = parent.slice(0, key)
+      return [
+        ...(prefix.length ? prefix : new Array(key)),
+        doSet(parent[key]),
+        ...parent.slice(key + 1),
+      ]
+    }
+    return [...new Array(key), doSet()]
+  }
+
+  return doSet(obj)
+}
+
+/**
+ * Delete a field on an object using a path, including dot notation.
+ */
+export function deleteBy(obj: any, _path: any) {
+  const path = makePathArray(_path)
+
+  function doDelete(parent: any): any {
+    if (path.length === 1) {
+      const finalPath = path[0]!
+      const { [finalPath]: remove, ...rest } = parent
+      return rest
+    }
+
+    const key = path.shift()
+
+    if (typeof key === 'string') {
+      if (typeof parent === 'object') {
+        return {
+          ...parent,
+          [key]: doDelete(parent[key]),
+        }
+      }
+    }
+
     if (typeof key === 'number') {
       if (Array.isArray(parent)) {
         const prefix = parent.slice(0, key)
         return [
           ...(prefix.length ? prefix : new Array(key)),
-          doSet(parent[key]),
+          doDelete(parent[key]),
           ...parent.slice(key + 1),
         ]
       }
-      return [...new Array(key), doSet()]
     }
 
-    throw new Error('Uh oh!')
+    throw new Error('It seems we have created an infinite loop in deleteBy. ')
   }
 
-  return doSet(obj)
+  return doDelete(obj)
 }
 
 const reFindNumbers0 = /^(\d*)$/gm