Fix/array field validation

docs/reference/formApi.md

@@ -137,6 +137,14 @@ A class representing the Form API. It handles the logic and interactions with th
   validateAllFields(cause: ValidationCause): Promise<ValidationError[]>
   ```
   - Validates all fields in the form using the correct handlers for a given validation type.
+- ```tsx
+  validateArrayFieldsStartingFrom<TField extends DeepKeys<TFormData>>(field: TField, index: number, cause: ValidationCause): ValidationError[] | Promise<ValidationError[]>
+  ```
+  - Validates the children of a specified array in the form starting from a given index until the end using the correct handlers for a given validation type.
+- ```tsx
+  validateField<TField extends DeepKeys<TFormData>>(field: TField, cause: ValidationCause): ValidationError[] | Promise<ValidationError[]>
+  ```
+  - Validates a specified field in the form using the correct handlers for a given validation type.
 
 - ```tsx
     handleSubmit()

packages/form-core/src/FieldApi.ts

@@ -477,9 +477,8 @@ export class FieldApi<
     value: TData extends any[] ? TData[number] : never,
   ) => this.form.insertFieldValue(this.name, index, value as any)
 
-  removeValue = async (index: number, opts?: { touch: boolean }) => {
-    await this.form.removeFieldValue(this.name, index, opts)
-  }
+  removeValue = (index: number, opts?: { touch: boolean }) =>
+    this.form.removeFieldValue(this.name, index, opts)
 
   swapValues = (aIndex: number, bIndex: number) =>
     this.form.swapFieldValues(this.name, aIndex, bIndex)

packages/form-core/src/FormApi.ts

@@ -370,6 +370,59 @@
     return fieldErrorMapMap.flat()
   }
 
+  validateArrayFieldsStartingFrom = async <TField extends DeepKeys<TFormData>>(
+    field: TField,
+    index: number,
+    cause: ValidationCause,
+  ) => {
+    const currentValue = this.getFieldValue(field)
+
+    const lastIndex = Array.isArray(currentValue)
+      ? Math.max(currentValue.length - 1, 0)
+      : null
+
+    // We have to validate all fields that have shifted (at least the current field)
+    const fieldKeysToValidate = [`${field}[${index}]`]
+    for (let i = index + 1; i <= (lastIndex ?? 0); i++) {
+      fieldKeysToValidate.push(`${field}[${i}]`)
+    }
+
+    // We also have to include all fields that are nested in the shifted fields
+    const fieldsToValidate = Object.keys(this.fieldInfo).filter((fieldKey) =>
+      fieldKeysToValidate.some((key) => fieldKey.startsWith(key)),
+    ) as DeepKeys<TFormData>[]
+
+    // Validate the fields
+    const fieldValidationPromises: Promise<ValidationError[]>[] = [] as any
+    this.store.batch(() => {
+      fieldsToValidate.forEach((nestedField) => {
+        fieldValidationPromises.push(
+          Promise.resolve().then(() => this.validateField(nestedField, cause)),
+        )
+      })
+    })
+
+    const fieldErrorMapMap = await Promise.all(fieldValidationPromises)
+    return fieldErrorMapMap.flat()
+  }
+
+  validateField = <TField extends DeepKeys<TFormData>>(
+    field: TField,
+    cause: ValidationCause,
+  ) => {
+    // eslint-disable-next-line  @typescript-eslint/no-unnecessary-condition
+    const fieldInstance = this.fieldInfo[field]?.instance
+    if (!fieldInstance) return []
+
+    // If the field is not touched (same logic as in validateAllFields)
+    if (!fieldInstance.state.meta.isTouched) {
+      // Mark it as touched
+      fieldInstance.setMeta((prev) => ({ ...prev, isTouched: true }))
+    }
+
+    return fieldInstance.validate(cause)
+  }
+
   // TODO: This code is copied from FieldApi, we should refactor to share
   validateSync = (cause: ValidationCause) => {
     const validates = getSyncValidatorArray(cause, this.options)
@@ -689,14 +742,15 @@
       : never,
     opts?: { touch?: boolean },
   ) => {
-    return this.setFieldValue(
+    this.setFieldValue(
       field,
       (prev) => [...(Array.isArray(prev) ? prev : []), value] as any,
       opts,
     )
+    this.validateField(field, 'change')
   }
 
-  insertFieldValue = <TField extends DeepKeys<TFormData>>(
+  insertFieldValue = async <TField extends DeepKeys<TFormData>>(
     field: TField,
     index: number,
     value: DeepValue<TFormData, TField> extends any[]
@@ -713,6 +767,10 @@
       },
       opts,
     )
+
+    // Validate the whole array + all fields that have shifted
+    await this.validateField(field, 'change')
+    await this.validateArrayFieldsStartingFrom(field, index, 'change')
   }
 
   removeFieldValue = async <TField extends DeepKeys<TFormData>>(
@@ -746,7 +804,9 @@
       fieldsToDelete.forEach((f) => this.deleteField(f as TField))
     }
 
-    await this.validateAllFields('change')
+    // Validate the whole array + all fields that have shifted
+    await this.validateField(field, 'change')
+    await this.validateArrayFieldsStartingFrom(field, index, 'change')
   }
 
   swapFieldValues = <TField extends DeepKeys<TFormData>>(
@@ -759,6 +819,12 @@
       const prev2 = prev[index2]!
       return setBy(setBy(prev, `${index1}`, prev2), `${index2}`, prev1)
     })
+
+    // Validate the whole array
+    this.validateField(field, 'change')
+    // Validate the swapped fields
+    this.validateField(`${field}[${index1}]` as DeepKeys<TFormData>, 'change')
+    this.validateField(`${field}[${index2}]` as DeepKeys<TFormData>, 'change')
   }
 
   moveFieldValues = <TField extends DeepKeys<TFormData>>(
@@ -770,6 +836,12 @@
       prev.splice(index2, 0, prev.splice(index1, 1)[0])
       return prev
     })
+
+    // Validate the whole array
+    this.validateField(field, 'change')
+    // Validate the moved fields
+    this.validateField(`${field}[${index1}]` as DeepKeys<TFormData>, 'change')
+    this.validateField(`${field}[${index2}]` as DeepKeys<TFormData>, 'change')
   }
 }
 

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

@@ -107,6 +107,35 @@ describe('field api', () => {
     expect(field.getValue()).toStrictEqual(['one', 'other'])
   })
 
+  it('should run onChange validation when pushing an array fields value', async () => {
+    const form = new FormApi({
+      defaultValues: {
+        names: ['test'],
+      },
+    })
+    form.mount()
+
+    const field = new FieldApi({
+      form,
+      name: 'names',
+      validators: {
+        onChange: ({ value }) => {
+          if (value.length < 3) {
+            return 'At least 3 names are required'
+          }
+          return
+        },
+      },
+    })
+    field.mount()
+
+    field.pushValue('other')
+
+    expect(field.getMeta().errors).toStrictEqual([
+      'At least 3 names are required',
+    ])
+  })
+
   it('should insert a value into an array value correctly', () => {
     const form = new FormApi({
       defaultValues: {
@@ -124,6 +153,38 @@ describe('field api', () => {
     expect(field.getValue()).toStrictEqual(['one', 'other'])
   })
 
+  it('should run onChange validation when inserting an array fields value', () => {
+    const form = new FormApi({
+      defaultValues: {
+        names: ['test'],
+      },
+    })
+    form.mount()
+
+    const field = new FieldApi({
+      form,
+      name: 'names',
+      validators: {
+        onChange: ({ value }) => {
+          if (value.length < 3) {
+            return 'At least 3 names are required'
+          }
+          return
+        },
+      },
+      defaultMeta: {
+        isTouched: true,
+      },
+    })
+    field.mount()
+
+    field.insertValue(1, 'other')
+
+    expect(field.getMeta().errors).toStrictEqual([
+      'At least 3 names are required',
+    ])
+  })
+
   it('should remove a value from an array value correctly', () => {
     const form = new FormApi({
       defaultValues: {
@@ -141,6 +202,38 @@ describe('field api', () => {
     expect(field.getValue()).toStrictEqual(['one'])
   })
 
+  it('should run onChange validation when removing an array fields value', async () => {
+    const form = new FormApi({
+      defaultValues: {
+        names: ['test'],
+      },
+    })
+    form.mount()
+
+    const field = new FieldApi({
+      form,
+      name: 'names',
+      validators: {
+        onChange: ({ value }) => {
+          if (value.length < 3) {
+            return 'At least 3 names are required'
+          }
+          return
+        },
+      },
+      defaultMeta: {
+        isTouched: true,
+      },
+    })
+    field.mount()
+
+    await field.removeValue(0)
+
+    expect(field.getMeta().errors).toStrictEqual([
+      'At least 3 names are required',
+    ])
+  })
+
   it('should remove a subfield from an array field correctly', async () => {
     const form = new FormApi({
       defaultValues: {
@@ -269,6 +362,38 @@ describe('field api', () => {
     expect(field.getValue()).toStrictEqual(['two', 'one'])
   })
 
+  it('should run onChange validation when swapping an array fields value', () => {
+    const form = new FormApi({
+      defaultValues: {
+        names: ['test', 'test2'],
+      },
+    })
+    form.mount()
+
+    const field = new FieldApi({
+      form,
+      name: 'names',
+      validators: {
+        onChange: ({ value }) => {
+          if (value.length < 3) {
+            return 'At least 3 names are required'
+          }
+          return
+        },
+      },
+      defaultMeta: {
+        isTouched: true,
+      },
+    })
+    field.mount()
+
+    field.swapValues(0, 1)
+
+    expect(field.getMeta().errors).toStrictEqual([
+      'At least 3 names are required',
+    ])
+  })
+
   it('should move a value from an array value correctly', () => {
     const form = new FormApi({
       defaultValues: {
@@ -286,6 +411,38 @@ describe('field api', () => {
     expect(field.getValue()).toStrictEqual(['three', 'one', 'two', 'four'])
   })
 
+  it('should run onChange validation when moving an array fields value', () => {
+    const form = new FormApi({
+      defaultValues: {
+        names: ['test', 'test2'],
+      },
+    })
+    form.mount()
+
+    const field = new FieldApi({
+      form,
+      name: 'names',
+      validators: {
+        onChange: ({ value }) => {
+          if (value.length < 3) {
+            return 'At least 3 names are required'
+          }
+          return
+        },
+      },
+      defaultMeta: {
+        isTouched: true,
+      },
+    })
+    field.mount()
+
+    field.moveValue(0, 1)
+
+    expect(field.getMeta().errors).toStrictEqual([
+      'At least 3 names are required',
+    ])
+  })
+
   it('should not throw errors when no meta info is stored on a field and a form re-renders', async () => {
     const form = new FormApi({
       defaultValues: {