interface FieldStorageDefinitionInterface

interface FieldStorageDefinitionInterface extends CacheableDependencyInterface {
    
    /**
     * Value indicating a field accepts an unlimited number of values.
     */
    const CARDINALITY_UNLIMITED = -1;
    
    /**
     * Returns the machine name of the field.
     *
     * This defines how the field data is accessed from the entity. For example,
     * if the field name is "foo", then $entity->foo returns its data.
     *
     * @return string
     *   The field name.
     */
    public function getName();
    
    /**
     * Returns the field type.
     *
     * @return string
     *   The field type, i.e. the id of a field type plugin. For example 'text'.
     *
     * @see \Drupal\Core\Field\FieldTypePluginManagerInterface
     */
    public function getType();
    
    /**
     * Returns the storage settings.
     *
     * Each field type defines the settings that are meaningful for that type.
     * For example, a text field can define a 'max_length' setting, and an image
     * field can define an 'alt_field_required' setting.
     *
     * The method always returns an array of all available settings for this field
     * type, possibly with the default values merged in if values have not been
     * provided for all available settings.
     *
     * @return mixed[]
     *   An array of key/value pairs.
     */
    public function getSettings();
    
    /**
     * Returns the value of a given storage setting.
     *
     * @param string $setting_name
     *   The setting name.
     *
     * @return mixed
     *   The setting value or NULL if the setting name doesn't exist.
     */
    public function getSetting($setting_name);
    
    /**
     * Returns whether the field supports translation.
     *
     * @return bool
     *   TRUE if the field supports translation.
     */
    public function isTranslatable();
    
    /**
     * Sets whether the field supports translation.
     *
     * @param bool $translatable
     *   Whether the field supports translation.
     *
     * @return $this
     */
    public function setTranslatable($translatable);
    
    /**
     * Returns whether the field storage is revisionable.
     *
     * Note that if the entity type is revisionable and the field storage has a
     * cardinality higher than 1, the field storage is considered revisionable
     * by default.
     *
     * @return bool
     *   TRUE if the field is revisionable.
     */
    public function isRevisionable();
    
    /**
     * Returns the human-readable label for the field.
     *
     * @return string
     *   The field label.
     */
    public function getLabel();
    
    /**
     * Returns the human-readable description for the field.
     *
     * This is displayed in addition to the label in places where additional
     * descriptive information is helpful. For example, as help text below the
     * form element in entity edit forms.
     *
     * @return string|null
     *   The field description, or NULL if no description is available.
     */
    public function getDescription();
    
    /**
     * Gets an options provider for the given field item property.
     *
     * @param string $property_name
     *   The name of the property to get options for; e.g., 'value'.
     * @param \Drupal\Core\Entity\FieldableEntityInterface $entity
     *   The entity for which the options should be provided.
     *
     * @return \Drupal\Core\TypedData\OptionsProviderInterface|null
     *   An options provider, or NULL if no options are defined.
     */
    public function getOptionsProvider($property_name, FieldableEntityInterface $entity);
    
    /**
     * Returns whether the field can contain multiple items.
     *
     * @return bool
     *   TRUE if the field can contain multiple items, FALSE otherwise.
     */
    public function isMultiple();
    
    /**
     * Returns the maximum number of items allowed for the field.
     *
     * Possible values are positive integers or
     * FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED.
     *
     * @return int
     *   The field cardinality.
     */
    public function getCardinality();
    
    /**
     * Gets the definition of a contained property.
     *
     * @param string $name
     *   The name of property.
     *
     * @return \Drupal\Core\TypedData\DataDefinitionInterface|null
     *   The definition of the property or NULL if the property does not exist.
     */
    public function getPropertyDefinition($name);
    
    /**
     * Gets an array of property definitions of contained properties.
     *
     * @return \Drupal\Core\TypedData\DataDefinitionInterface[]
     *   An array of property definitions of contained properties, keyed by
     *   property name.
     */
    public function getPropertyDefinitions();
    
    /**
     * Returns the names of the field's subproperties.
     *
     * A field is a list of items, and each item can contain one or more
     * properties. All items for a given field contain the same property names,
     * but the values can be different for each item.
     *
     * For example, an email field might just contain a single 'value' property,
     * while a link field might contain 'title' and 'url' properties, and a text
     * field might contain 'value', 'summary', and 'format' properties.
     *
     * @return string[]
     *   The property names.
     */
    public function getPropertyNames();
    
    /**
     * Returns the name of the main property, if any.
     *
     * Some field items consist mainly of one main property, e.g. the value of a
     * text field or the @code target_id @endcode of an entity reference. If the
     * field item has no main property, the method returns NULL.
     *
     * @return string|null
     *   The name of the value property, or NULL if there is none.
     */
    public function getMainPropertyName();
    
    /**
     * Returns the ID of the entity type the field is attached to.
     *
     * This method should not be confused with EntityInterface::getEntityTypeId()
     * (configurable fields are config entities, and thus implement both
     * interfaces):
     *   - FieldStorageDefinitionInterface::getTargetEntityTypeId() answers "as a
     *     field storage, which entity type are you attached to?".
     *   - EntityInterface::getEntityTypeId() answers "as a (config) entity, what
     *     is your own entity type?".
     *
     * @return string
     *   The entity type ID.
     */
    public function getTargetEntityTypeId();
    
    /**
     * Returns the field schema.
     *
     * Note that this method returns an empty array for computed fields which have
     * no schema.
     *
     * @return array[]
     *   The field schema, as an array of key/value pairs in the format returned
     *   by \Drupal\Core\Field\FieldItemInterface::schema():
     *   - columns: An array of Schema API column specifications, keyed by column
     *     name. This specifies what comprises a single value for a given field.
     *     No assumptions should be made on how storage backends internally use
     *     the original column name to structure their storage.
     *   - indexes: An array of Schema API index definitions. Some storage
     *     backends might not support indexes.
     *   - unique keys: An array of Schema API unique key definitions.  Some
     *     storage backends might not support unique keys.
     *   - foreign keys: An array of Schema API foreign key definitions. Note,
     *     however, that depending on the storage backend specified for the field,
     *     the field data is not necessarily stored in SQL.
     */
    public function getSchema();
    
    /**
     * Returns the field columns, as defined in the field schema.
     *
     * @return array[]
     *   The array of field columns, keyed by column name, in the same format
     *   returned by getSchema().
     *
     * @see \Drupal\Core\Field\FieldStorageDefinitionInterface::getSchema()
     */
    public function getColumns();
    
    /**
     * Returns an array of validation constraints.
     *
     * See \Drupal\Core\TypedData\DataDefinitionInterface::getConstraints() for
     * details.
     *
     * @return array[]
     *   An array of validation constraint definitions, keyed by constraint name.
     *   Each constraint definition can be used for instantiating
     *   \Symfony\Component\Validator\Constraint objects.
     *
     * @see \Symfony\Component\Validator\Constraint
     */
    public function getConstraints();
    
    /**
     * Returns a validation constraint.
     *
     * See \Drupal\Core\TypedData\DataDefinitionInterface::getConstraints() for
     * details.
     *
     * @param string $constraint_name
     *   The name of the constraint, i.e. its plugin id.
     *
     * @return array
     *   A validation constraint definition which can be used for instantiating a
     *   \Symfony\Component\Validator\Constraint object.
     *
     * @see \Symfony\Component\Validator\Constraint
     */
    public function getConstraint($constraint_name);
    
    /**
     * Returns the name of the provider of this field.
     *
     * @return string
     *   The provider name; e.g., the module name.
     */
    public function getProvider();
    
    /**
     * Returns the storage behavior for this field.
     *
     * Indicates whether the entity type's storage should take care of storing the
     * field values or whether it is handled separately; e.g. by the
     * module providing the field.
     *
     * @return bool
     *   FALSE if the storage takes care of storing the field, TRUE otherwise.
     */
    public function hasCustomStorage();
    
    /**
     * Determines whether the field is a base field.
     *
     * Base fields are not specific to a given bundle or a set of bundles. This
     * excludes configurable fields, as they are always attached to a specific
     * bundle.
     *
     * @return bool
     *   Whether the field is a base field.
     */
    public function isBaseField();
    
    /**
     * Returns a unique identifier for the field storage.
     *
     * @return string
     */
    public function getUniqueStorageIdentifier();
    
    /**
     * Returns whether the field is deleted or not.
     *
     * @return bool
     *   TRUE if the field is deleted, FALSE otherwise.
     */
    public function isDeleted();

}