# Metafields
The API for interacting with metafields.

## StandardApi
The base API object provided to `purchase` extension targets.
### Docs_Standard_MetafieldsApi

### appMetafields
The metafields requested in the [`shopify.extension.toml`](/docs/api/checkout-ui-extensions/configuration) file. These metafields are updated when there's a change in the merchandise items being purchased by the customer.

{% include /apps/checkout/privacy-icon.md %} Requires access to [protected customer data](/docs/apps/store/data-protection/protected-customer-data).

> Tip: > Cart metafields are only available on carts created via the Storefront API version `2023-04` or later.*
### metafields
The metafields that apply to the current checkout.

Metafields are stored locally on the client and are applied to the order object after the checkout completes.

These metafields are shared by all extensions running on checkout, and persist for as long as the customer is working on this checkout.

Once the order is created, you can query these metafields using the [GraphQL Admin API](/docs/admin-api/graphql/reference/orders/order#metafield-2021-01)
### AppMetafieldEntry
A metafield associated with the shop or a resource on the checkout.
### metafield
The metadata information.
### target
The target that is associated to the metadata.

{% include /apps/checkout/privacy-icon.md %} Requires access to [protected customer data](/docs/apps/store/data-protection/protected-customer-data) when the type is `customer`, `company` or `companyLocation`.
### AppMetafield
Represents a custom metadata attached to a resource.
### key
The key name of a metafield.
### namespace
The namespace for a metafield.
### type
The metafield's type name.
### value
The value of a metafield.
### valueType
The metafield’s information type.
### AppMetafieldEntryTarget
The metafield owner.
### id
The numeric owner ID that is associated with the metafield.
### type
The type of the metafield owner.

{% include /apps/checkout/privacy-icon.md %} Requires access to [protected customer data](/docs/apps/store/data-protection/protected-customer-data) when the type is `customer`, `company` or `companyLocation`.
### Metafield
Metadata associated with the checkout.
### key
The name of the metafield. It must be between 3 and 30 characters in length (inclusive).
### namespace
A container for a set of metafields. You need to define a custom namespace for your metafields to distinguish them from the metafields used by other apps. This must be between 2 and 20 characters in length (inclusive).
### value
The information to be stored as metadata.
### valueType
The metafield’s information type.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)
## useAppMetafields
Returns the metafields configured with `shopify.extension.toml`.
### UseAppMetafieldsGeneratedType
Returns the metafields configured with `shopify.extension.toml`.
#### Returns: AppMetafieldEntry[]

#### Params:
- filters: AppMetafieldFilters
export function useAppMetafields<
  Target extends RenderExtensionTarget = RenderExtensionTarget,
>(filters: AppMetafieldFilters = {}): AppMetafieldEntry[] {
  const appMetafields = useSubscription(useApi<Target>().appMetafields);

  return useMemo(() => {
    if (filters.key && !filters.namespace) {
      throw new CheckoutUIExtensionError(
        'You must pass in a namespace with a key',
      );
    }

    const filterKeys = Object.keys(filters) as AppMetafieldFilterKeys[];

    if (filterKeys.length) {
      return appMetafields.filter((app) => {
        return filterKeys.every((key) => {
          if (key === 'id' || key === 'type') {
            return app.target[key] === filters[key];
          }

          return app.metafield[key] === filters[key];
        });
      });
    }

    return appMetafields;
  }, [filters, appMetafields]);
}
### AppMetafieldFilters

### id

### key

### namespace

### type

### AppMetafieldEntry
A metafield associated with the shop or a resource on the checkout.
### metafield
The metadata information.
### target
The target that is associated to the metadata.

{% include /apps/checkout/privacy-icon.md %} Requires access to [protected customer data](/docs/apps/store/data-protection/protected-customer-data) when the type is `customer`, `company` or `companyLocation`.
### AppMetafield
Represents a custom metadata attached to a resource.
### key
The key name of a metafield.
### namespace
The namespace for a metafield.
### type
The metafield's type name.
### value
The value of a metafield.
### valueType
The metafield’s information type.
### AppMetafieldEntryTarget
The metafield owner.
### id
The numeric owner ID that is associated with the metafield.
### type
The type of the metafield owner.

{% include /apps/checkout/privacy-icon.md %} Requires access to [protected customer data](/docs/apps/store/data-protection/protected-customer-data) when the type is `customer`, `company` or `companyLocation`.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)
## useMetafield
Returns a single filtered `Metafield` or `undefined`.
### UseMetafieldGeneratedType
Returns a single filtered `Metafield` or `undefined`.
#### Returns: Metafield | undefined

#### Params:
- filters: MetafieldFilter
export function useMetafield(filters: MetafieldFilter): Metafield | undefined {
  const {namespace, key} = filters;

  if (!namespace || !key) {
    throw new CheckoutUIExtensionError(
      'You must pass in both a namespace and key',
    );
  }

  const metafields = useMetafields({namespace, key});

  return metafields.length ? metafields[0] : undefined;
}
### MetafieldFilter

### key

### namespace

### Metafield
Metadata associated with the checkout.
### key
The name of the metafield. It must be between 3 and 30 characters in length (inclusive).
### namespace
A container for a set of metafields. You need to define a custom namespace for your metafields to distinguish them from the metafields used by other apps. This must be between 2 and 20 characters in length (inclusive).
### value
The information to be stored as metadata.
### valueType
The metafield’s information type.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)
## useMetafields
Returns the current array of `metafields` applied to the checkout. You can optionally filter the list.
### UseMetafieldsGeneratedType
Returns the current array of `metafields` applied to the checkout. You can optionally filter the list.
#### Returns: Metafield[]

#### Params:
- filters: MetafieldsFilters
export function useMetafields<
  Target extends RenderExtensionTarget = RenderExtensionTarget,
>(filters?: MetafieldsFilters): Metafield[] {
  const metaFields = useSubscription(useApi<Target>().metafields);

  return useMemo(() => {
    if (filters) {
      const {namespace, key} = filters;

      if (!namespace) {
        throw new CheckoutUIExtensionError(
          'You must pass in a namespace with a key',
        );
      }

      const filteredResults = metaFields.filter(
        (metafield) =>
          metafield.namespace === namespace && (!key || metafield.key === key),
      );

      return filteredResults;
    }

    return metaFields;
  }, [filters, metaFields]);
}
### MetafieldsFilters

### key

### namespace

### Metafield
Metadata associated with the checkout.
### key
The name of the metafield. It must be between 3 and 30 characters in length (inclusive).
### namespace
A container for a set of metafields. You need to define a custom namespace for your metafields to distinguish them from the metafields used by other apps. This must be between 2 and 20 characters in length (inclusive).
### value
The information to be stored as metadata.
### valueType
The metafield’s information type.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)
## CheckoutApi
The API object provided to `purchase.checkout` extension targets.
### Docs_Checkout_MetafieldsApi

### applyMetafieldChange
Performs an update on a piece of metadata attached to the checkout. If successful, this mutation results in an update to the value retrieved through the [`metafields`](/docs/api/checkout-ui-extensions/apis/metafields#standardapi-propertydetail-metafields) property.

> Note: This method will return an error if the [cart instruction](/docs/api/checkout-ui-extensions/apis/cart-instructions#standardapi-propertydetail-instructions) `metafields.canSetCartMetafields` is false, or the buyer is using an accelerated checkout method, such as Apple Pay, Google Pay, or Meta Pay.
### MetafieldChange

MetafieldRemoveChange | MetafieldUpdateChange | MetafieldRemoveCartChange | MetafieldUpdateCartChange
### MetafieldRemoveChange
Removes a metafield.
### key
The name of the metafield to remove.
### namespace
The namespace of the metafield to remove.
### type
The type of the `MetafieldRemoveChange` API.
### Metafield
Metadata associated with the checkout.
### key
The name of the metafield. It must be between 3 and 30 characters in length (inclusive).
### namespace
A container for a set of metafields. You need to define a custom namespace for your metafields to distinguish them from the metafields used by other apps. This must be between 2 and 20 characters in length (inclusive).
### value
The information to be stored as metadata.
### valueType
The metafield’s information type.
### MetafieldUpdateChange
Updates a metafield. If a metafield with the provided key and namespace does not already exist, it gets created.
### key
The name of the metafield to update.
### namespace
The namespace of the metafield to add.
### type
The type of the `MetafieldUpdateChange` API.
### value
The new information to store in the metafield.
### valueType
The metafield’s information type.
### MetafieldRemoveCartChange
Removes a cart metafield.
### key
The name of the metafield to remove.
### namespace
The namespace of the metafield to remove.
### type
The type of the `MetafieldRemoveChange` API.
### CartMetafield
Represents a custom metadata attached to a resource.
### key
The key name of a metafield.
### namespace
The namespace for a metafield.
### type
The metafield's type name.
### value
The value of a metafield.
### MetafieldUpdateCartChange
Updates a cart metafield. If a metafield with the provided key and namespace does not already exist, it gets created.
### metafield

### type
The type of the `MetafieldUpdateChange` API.
### MetafieldChangeResult

MetafieldChangeResultSuccess | MetafieldChangeResultError
### MetafieldChangeResultSuccess

### type
The type of the `MetafieldChangeResultSuccess` API.
### MetafieldChangeResultError

### message
A message that explains the error. This message is useful for debugging. It is **not** localized, and therefore should not be presented directly to the buyer.
### type
The type of the `MetafieldChangeResultError` API.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)
## useApplyMetafieldsChange
Returns a function to mutate the `metafields` property of the checkout.
### UseApplyMetafieldsChangeGeneratedType
Returns a function to mutate the `metafields` property of the checkout.
#### Returns: (change: MetafieldChange) => Promise<MetafieldChangeResult>

export function useApplyMetafieldsChange<
  Target extends RenderExtensionTarget = RenderExtensionTarget,
>(): (change: MetafieldChange) => Promise<MetafieldChangeResult> {
  const api = useApi<Target>();

  if ('applyMetafieldChange' in api) {
    return api.applyMetafieldChange;
  }

  throw new ExtensionHasNoMethodError(
    'applyMetafieldChange',
    api.extension.target,
  );
}
### MetafieldChange

MetafieldRemoveChange | MetafieldUpdateChange | MetafieldRemoveCartChange | MetafieldUpdateCartChange
### MetafieldRemoveChange
Removes a metafield.
### key
The name of the metafield to remove.
### namespace
The namespace of the metafield to remove.
### type
The type of the `MetafieldRemoveChange` API.
### Metafield
Metadata associated with the checkout.
### key
The name of the metafield. It must be between 3 and 30 characters in length (inclusive).
### namespace
A container for a set of metafields. You need to define a custom namespace for your metafields to distinguish them from the metafields used by other apps. This must be between 2 and 20 characters in length (inclusive).
### value
The information to be stored as metadata.
### valueType
The metafield’s information type.
### MetafieldUpdateChange
Updates a metafield. If a metafield with the provided key and namespace does not already exist, it gets created.
### key
The name of the metafield to update.
### namespace
The namespace of the metafield to add.
### type
The type of the `MetafieldUpdateChange` API.
### value
The new information to store in the metafield.
### valueType
The metafield’s information type.
### MetafieldRemoveCartChange
Removes a cart metafield.
### key
The name of the metafield to remove.
### namespace
The namespace of the metafield to remove.
### type
The type of the `MetafieldRemoveChange` API.
### CartMetafield
Represents a custom metadata attached to a resource.
### key
The key name of a metafield.
### namespace
The namespace for a metafield.
### type
The metafield's type name.
### value
The value of a metafield.
### MetafieldUpdateCartChange
Updates a cart metafield. If a metafield with the provided key and namespace does not already exist, it gets created.
### metafield

### type
The type of the `MetafieldUpdateChange` API.
### MetafieldChangeResult

MetafieldChangeResultSuccess | MetafieldChangeResultError
### MetafieldChangeResultSuccess

### type
The type of the `MetafieldChangeResultSuccess` API.
### MetafieldChangeResultError

### message
A message that explains the error. This message is useful for debugging. It is **not** localized, and therefore should not be presented directly to the buyer.
### type
The type of the `MetafieldChangeResultError` API.
## Related
- [Targets](/docs/api/checkout-ui-extensions/targets)
- [Components](/docs/api/checkout-ui-extensions/components)
- [Configuration](/docs/api/checkout-ui-extensions/configuration)
- [Tutorials](/apps/checkout)