Issue #2161337 by mpdonadio, darrick, swentel, effulgentsia, YesCT, xjm,...

Issue #2161337 by mpdonadio, darrick, swentel, effulgentsia, YesCT, xjm, Berdir, tim.plunkett, pguillard, SKAUGHT, sylus, jonathanjfshaw, FluxSauce, DuneBL, jhedstrom, dawehner, generalredneck, pjonckiere, borisson_, Gábor Hojtsy, webchick, miwayha: Add a Date Range field type with support for end date

core/MAINTAINERS.txt

@@ -324,6 +324,10 @@ DateTime module
 - Jonathan Hedstrom 'jhedstrom' https://www.drupal.org/u/jhedstrom
 - Matthew Donadio 'mpdonadio' https://www.drupal.org/u/mpdonadio
 
+DateTime range module
+- Jonathan Hedstrom 'jhedstrom' https://www.drupal.org/u/jhedstrom
+- Matthew Donadio 'mpdonadio' https://www.drupal.org/u/mpdonadio
+
 Dynamic Page Cache module
 - Fabian Franz 'Fabianx' https://www.drupal.org/u/fabianx
 - Wim Leers 'Wim Leers' https://www.drupal.org/u/wim-leers

core/composer.json

@@ -88,6 +88,7 @@
         "drupal/core-utility": "self.version",
         "drupal/core-uuid": "self.version",
         "drupal/datetime": "self.version",
+        "drupal/datetime_range": "self.version",
         "drupal/dblog": "self.version",
         "drupal/dynamic_page_cache": "self.version",
         "drupal/editor": "self.version",

core/modules/datetime_range/config/schema/datetime_range.schema.yml

+# Schema for the configuration files of the Datetime Range module.
+
+# Daterange field type.
+
+field.storage_settings.daterange:
+  type: field.storage_settings.datetime
+  label: 'Date range settings'
+
+field.field_settings.daterange:
+  type: field.field_settings.datetime
+  label: 'Date range settings'
+
+field.value.daterange:
+  type: mapping
+  label: 'Default value'
+  mapping:
+    default_date_type:
+      type: string
+      label: 'Default start date type'
+    default_date:
+      type: string
+      label: 'Default start date value'
+    default_end_date_type:
+      type: string
+      label: 'Default end date type'
+    default_end_date:
+      type: string
+      label: 'Default end date value'
+
+field.formatter.settings.daterange_default:
+  type: field.formatter.settings.datetime_default
+  label: 'Date range default display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
+
+field.formatter.settings.daterange_plain:
+  type: field.formatter.settings.datetime_plain
+  label: 'Date range plain display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
+
+field.formatter.settings.daterange_custom:
+  type: field.formatter.settings.datetime_custom
+  label: 'Date range custom display format settings'
+  mapping:
+    separator:
+      type: string
+      label: 'Separator'
+
+field.widget.settings.daterange_datelist:
+  type: mapping
+  label: 'Date range select list display format settings'
+  mapping:
+    increment:
+      type: integer
+      label: 'Time increments'
+    date_order:
+      type: string
+      label: 'Date part order'
+    time_type:
+      type: string
+      label: 'Time type'
+
+field.widget.settings.daterange_default:
+  type: mapping
+  label: 'Date range default display format settings'

core/modules/datetime_range/datetime_range.info.yml

+name: 'Datetime Range'
+type: module
+description: 'Provides the ability to store end dates.'
+package: Core (Experimental)
+version: VERSION
+core: 8.x
+dependencies:
+  - datetime

core/modules/datetime_range/datetime_range.module

+<?php
+
+/**
+ * @file
+ * Field hooks to implement a datetime field that stores a start and end date.
+ */
+
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Implements hook_help().
+ */
+function datetime_range_help($route_name, RouteMatchInterface $route_match) {
+  switch ($route_name) {
+    case 'help.page.datetime_range':
+      $output = '';
+      $output .= '<h3>' . t('About') . '</h3>';
+      $output .= '<p>' . t('The Datetime Range module provides a Date field that stores start dates and times, as well as end dates and times. See the <a href=":field">Field module help</a> and the <a href=":field_ui">Field UI module help</a> pages for general information on fields and how to create and manage them. For more information, see the <a href=":datetime_do">online documentation for the Datetime Range module</a>.', array(':field' => \Drupal::url('help.page', array('name' => 'field')), ':field_ui' => (\Drupal::moduleHandler()->moduleExists('field_ui')) ? \Drupal::url('help.page', array('name' => 'field_ui')) : '#', ':datetime_do' => 'https://www.drupal.org/documentation/modules/datetime_range')) . '</p>';
+      $output .= '<h3>' . t('Uses') . '</h3>';
+      $output .= '<dl>';
+      $output .= '<dt>' . t('Managing and displaying date fields') . '</dt>';
+      $output .= '<dd>' . t('The <em>settings</em> and the <em>display</em> of the Date field can be configured separately. See the <a href=":field_ui">Field UI help</a> for more information on how to manage fields and their display.', array(':field_ui' => (\Drupal::moduleHandler()->moduleExists('field_ui')) ? \Drupal::url('help.page', array('name' => 'field_ui')) : '#')) . '</dd>';
+      $output .= '<dt>' . t('Displaying dates') . '</dt>';
+      $output .= '<dd>' . t('Dates can be displayed using the <em>Plain</em> or the <em>Default</em> formatter. The <em>Plain</em> formatter displays the date in the <a href="http://en.wikipedia.org/wiki/ISO_8601">ISO 8601</a> format. If you choose the <em>Default</em> formatter, you can choose a format from a predefined list that can be managed on the <a href=":date_format_list">Date and time formats</a> page.', array(':date_format_list' => \Drupal::url('entity.date_format.collection'))) . '</dd>';
+      $output .= '</dl>';
+      return $output;
+  }
+}

core/modules/datetime_range/src/DateTimeRangeTrait.php

+<?php
+
+namespace Drupal\datetime_range;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
+
+/**
+ * Provides friendly methods for datetime range.
+ */
+trait DateTimeRangeTrait {
+
+  /**
+   * Creates a render array from a date object.
+   *
+   * @param \Drupal\Core\Datetime\DrupalDateTime $date
+   *   A date object.
+   *
+   * @return array
+   *   A render array.
+   */
+  protected function buildDate(DrupalDateTime $date) {
+    if ($this->getFieldSetting('datetime_type') == DateTimeItem::DATETIME_TYPE_DATE) {
+      // A date without time will pick up the current time, use the default.
+      datetime_date_default_time($date);
+    }
+    $this->setTimeZone($date);
+
+    $build = [
+      '#plain_text' => $this->formatDate($date),
+      '#cache' => [
+        'contexts' => [
+          'timezone',
+        ],
+      ],
+    ];
+
+    return $build;
+  }
+
+  /**
+   * Creates a render array from a date object with ISO date attribute.
+   *
+   * @param \Drupal\Core\Datetime\DrupalDateTime $date
+   *   A date object.
+   *
+   * @return array
+   *   A render array.
+   */
+  protected function buildDateWithIsoAttribute(DrupalDateTime $date) {
+    if ($this->getFieldSetting('datetime_type') == DateTimeItem::DATETIME_TYPE_DATE) {
+      // A date without time will pick up the current time, use the default.
+      datetime_date_default_time($date);
+    }
+
+    // Create the ISO date in Universal Time.
+    $iso_date = $date->format("Y-m-d\TH:i:s") . 'Z';
+
+    $this->setTimeZone($date);
+
+    $build = [
+      '#theme' => 'time',
+      '#text' => $this->formatDate($date),
+      '#html' => FALSE,
+      '#attributes' => [
+        'datetime' => $iso_date,
+      ],
+      '#cache' => [
+        'contexts' => [
+          'timezone',
+        ],
+      ],
+    ];
+
+    return $build;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeCustomFormatter.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime\Plugin\Field\FieldFormatter\DateTimeCustomFormatter;
+use Drupal\datetime_range\DateTimeRangeTrait;
+
+/**
+ * Plugin implementation of the 'Custom' formatter for 'daterange' fields.
+ *
+ * This formatter renders the data range as plain text, with a fully
+ * configurable date format using the PHP date syntax and separator.
+ *
+ * @FieldFormatter(
+ *   id = "daterange_custom",
+ *   label = @Translation("Custom"),
+ *   field_types = {
+ *     "daterange"
+ *   }
+ * )
+ */
+class DateRangeCustomFormatter extends DateTimeCustomFormatter {
+
+  use DateTimeRangeTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'separator' => '-',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    $elements = [];
+    $separator = $this->getSetting('separator');
+
+    foreach ($items as $delta => $item) {
+      if (!empty($item->start_date) && !empty($item->end_date)) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $start_date = $item->start_date;
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
+        $end_date = $item->end_date;
+
+        if ($start_date->format('U') !== $end_date->format('U')) {
+          $elements[$delta] = [
+            'start_date' => $this->buildDate($start_date),
+            'separator' => ['#plain_text' => ' ' . $separator . ' '],
+            'end_date' => $this->buildDate($end_date),
+          ];
+        }
+        else {
+          $elements[$delta] = $this->buildDate($start_date);
+        }
+      }
+    }
+
+    return $elements;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    $form = parent::settingsForm($form, $form_state);
+
+    $form['separator'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Date separator'),
+      '#description' => $this->t('The string to separate the start and end dates'),
+      '#default_value' => $this->getSetting('separator'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = parent::settingsSummary();
+
+    if ($separator = $this->getSetting('separator')) {
+      $summary[] = $this->t('Separator: %separator', ['%separator' => $separator]);
+    }
+
+    return $summary;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangeDefaultFormatter.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime\Plugin\Field\FieldFormatter\DateTimeDefaultFormatter;
+use Drupal\datetime_range\DateTimeRangeTrait;
+
+/**
+ * Plugin implementation of the 'Default' formatter for 'daterange' fields.
+ *
+ * This formatter renders the data range using <time> elements, with
+ * configurable date formats (from the list of configured formats) and a
+ * separator.
+ *
+ * @FieldFormatter(
+ *   id = "daterange_default",
+ *   label = @Translation("Default"),
+ *   field_types = {
+ *     "daterange"
+ *   }
+ * )
+ */
+class DateRangeDefaultFormatter extends DateTimeDefaultFormatter {
+
+  use DateTimeRangeTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'separator' => '-',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    $elements = [];
+    $separator = $this->getSetting('separator');
+
+    foreach ($items as $delta => $item) {
+      if (!empty($item->start_date) && !empty($item->end_date)) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $start_date = $item->start_date;
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
+        $end_date = $item->end_date;
+
+        if ($start_date->format('U') !== $end_date->format('U')) {
+          $elements[$delta] = [
+            'start_date' => $this->buildDateWithIsoAttribute($start_date),
+            'separator' => ['#plain_text' => ' ' . $separator . ' '],
+            'end_date' => $this->buildDateWithIsoAttribute($end_date),
+          ];
+        }
+        else {
+          $elements[$delta] = $this->buildDateWithIsoAttribute($start_date);
+        }
+
+        if (!empty($item->_attributes)) {
+          $elements[$delta]['#attributes'] += $item->_attributes;
+          // Unset field item attributes since they have been included in the
+          // formatter output and should not be rendered in the field template.
+          unset($item->_attributes);
+        }
+      }
+    }
+
+    return $elements;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    $form = parent::settingsForm($form, $form_state);
+
+    $form['separator'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Date separator'),
+      '#description' => $this->t('The string to separate the start and end dates'),
+      '#default_value' => $this->getSetting('separator'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = parent::settingsSummary();
+
+    if ($separator = $this->getSetting('separator')) {
+      $summary[] = $this->t('Separator: %separator', ['%separator' => $separator]);
+    }
+
+    return $summary;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldFormatter/DateRangePlainFormatter.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldFormatter;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime\Plugin\Field\FieldFormatter\DateTimePlainFormatter;
+use Drupal\datetime_range\DateTimeRangeTrait;
+
+/**
+ * Plugin implementation of the 'Plain' formatter for 'daterange' fields.
+ *
+ * This formatter renders the data range as a plain text string, with a
+ * configurable separator using an ISO-like date format string.
+ *
+ * @FieldFormatter(
+ *   id = "daterange_plain",
+ *   label = @Translation("Plain"),
+ *   field_types = {
+ *     "daterange"
+ *   }
+ * )
+ */
+class DateRangePlainFormatter extends DateTimePlainFormatter {
+
+  use DateTimeRangeTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'separator' => '-',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function viewElements(FieldItemListInterface $items, $langcode) {
+    $elements = [];
+    $separator = $this->getSetting('separator');
+
+    foreach ($items as $delta => $item) {
+      if (!empty($item->start_date) && !empty($item->end_date)) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $start_date = $item->start_date;
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
+        $end_date = $item->end_date;
+
+        if ($start_date->format('U') !== $end_date->format('U')) {
+          $elements[$delta] = [
+            'start_date' => $this->buildDate($start_date),
+            'separator' => ['#plain_text' => ' ' . $separator . ' '],
+            'end_date' => $this->buildDate($end_date),
+          ];
+        }
+        else {
+          $elements[$delta] = $this->buildDate($start_date);
+        }
+      }
+    }
+
+    return $elements;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    $form = parent::settingsForm($form, $form_state);
+
+    $form['separator'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Date separator'),
+      '#description' => $this->t('The string to separate the start and end dates'),
+      '#default_value' => $this->getSetting('separator'),
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = parent::settingsSummary();
+
+    if ($separator = $this->getSetting('separator')) {
+      $summary[] = $this->t('Separator: %separator', ['%separator' => $separator]);
+    }
+
+    return $summary;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeFieldItemList.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldType;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\Core\Entity\FieldableEntityInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Field\FieldItemList;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeFieldItemList;
+
+/**
+ * Represents a configurable entity daterange field.
+ */
+class DateRangeFieldItemList extends DateTimeFieldItemList {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultValuesForm(array &$form, FormStateInterface $form_state) {
+    if (empty($this->getFieldDefinition()->getDefaultValueCallback())) {
+      $default_value = $this->getFieldDefinition()->getDefaultValueLiteral();
+
+      $element = parent::defaultValuesForm($form, $form_state);
+
+      $element['default_date_type']['#title'] = $this->t('Default start date');
+      $element['default_date_type']['#description'] = $this->t('Set a default value for the start date.');
+
+      $element['default_end_date_type'] = [
+        '#type' => 'select',
+        '#title' => $this->t('Default end date'),
+        '#description' => $this->t('Set a default value for the end date.'),
+        '#default_value' => isset($default_value[0]['default_end_date_type']) ? $default_value[0]['default_end_date_type'] : '',
+        '#options' => [
+          static::DEFAULT_VALUE_NOW => $this->t('Current date'),
+          static::DEFAULT_VALUE_CUSTOM => $this->t('Relative date'),
+        ],
+        '#empty_value' => '',
+      ];
+
+      $element['default_end_date'] = [
+        '#type' => 'textfield',
+        '#title' => $this->t('Relative default value'),
+        '#description' => $this->t("Describe a time by reference to the current day, like '+90 days' (90 days from the day the field is created) or '+1 Saturday' (the next Saturday). See <a href=\"http://php.net/manual/function.strtotime.php\">strtotime</a> for more details."),
+        '#default_value' => (isset($default_value[0]['default_end_date_type']) && $default_value[0]['default_end_date_type'] == static::DEFAULT_VALUE_CUSTOM) ? $default_value[0]['default_end_date'] : '',
+        '#states' => [
+          'visible' => [
+            ':input[id="edit-default-value-input-default-end-date-type"]' => ['value' => static::DEFAULT_VALUE_CUSTOM],
+          ],
+        ],
+      ];
+
+      return $element;
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultValuesFormValidate(array $element, array &$form, FormStateInterface $form_state) {
+    if ($form_state->getValue(['default_value_input', 'default_date_type']) == static::DEFAULT_VALUE_CUSTOM) {
+      $is_strtotime = @strtotime($form_state->getValue(['default_value_input', 'default_date']));
+      if (!$is_strtotime) {
+        $form_state->setErrorByName('default_value_input][default_date', $this->t('The relative start date value entered is invalid.'));
+      }
+    }
+
+    if ($form_state->getValue(['default_value_input', 'default_end_date_type']) == static::DEFAULT_VALUE_CUSTOM) {
+      $is_strtotime = @strtotime($form_state->getValue(['default_value_input', 'default_end_date']));
+      if (!$is_strtotime) {
+        $form_state->setErrorByName('default_value_input][default_end_date', $this->t('The relative end date value entered is invalid.'));
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultValuesFormSubmit(array $element, array &$form, FormStateInterface $form_state) {
+    if ($form_state->getValue(['default_value_input', 'default_date_type']) || $form_state->getValue(['default_value_input', 'default_end_date_type'])) {
+      if ($form_state->getValue(['default_value_input', 'default_date_type']) == static::DEFAULT_VALUE_NOW) {
+        $form_state->setValueForElement($element['default_date'], static::DEFAULT_VALUE_NOW);
+      }
+      if ($form_state->getValue(['default_value_input', 'default_end_date_type']) == static::DEFAULT_VALUE_NOW) {
+        $form_state->setValueForElement($element['default_end_date'], static::DEFAULT_VALUE_NOW);
+      }
+      return [$form_state->getValue('default_value_input')];
+    }
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function processDefaultValue($default_value, FieldableEntityInterface $entity, FieldDefinitionInterface $definition) {
+    // Explicitly call the base class so that we can get the default value
+    // types.
+    $default_value = FieldItemList::processDefaultValue($default_value, $entity, $definition);
+
+    // Allow either the start or end date to have a default, but not require
+    // defaults for both.
+    if (!empty($default_value[0]['default_date_type']) || !empty($default_value[0]['default_end_date_type'])) {
+      // A default value should be in the format and timezone used for date
+      // storage. All-day ranges are stored the same as date+time ranges.  We
+      // only provide a default value for the first item, as do all fields.
+      // Otherwise, there is no way to clear out unwanted values on multiple
+      // value fields.
+      $storage_format = $definition->getSetting('datetime_type') == DateRangeItem::DATETIME_TYPE_DATE ? DATETIME_DATE_STORAGE_FORMAT : DATETIME_DATETIME_STORAGE_FORMAT;
+      $default_values = [[]];
+
+      if (!empty($default_value[0]['default_date_type'])) {
+        $start_date = new DrupalDateTime($default_value[0]['default_date'], DATETIME_STORAGE_TIMEZONE);
+        $start_value = $start_date->format($storage_format);
+        $default_values[0]['value'] = $start_value;
+        $default_values[0]['start_date'] = $start_date;
+      }
+
+      if (!empty($default_value[0]['default_end_date_type'])) {
+        $end_date = new DrupalDateTime($default_value[0]['default_end_date'], DATETIME_STORAGE_TIMEZONE);
+        $end_value = $end_date->format($storage_format);
+        $default_values[0]['end_value'] = $end_value;
+        $default_values[0]['end_date'] = $end_date;
+      }
+
+      $default_value = $default_values;
+    }
+
+    return $default_value;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldType/DateRangeItem.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldType;
+
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\TypedData\DataDefinition;
+use Drupal\datetime\DateTimeComputed;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
+
+/**
+ * Plugin implementation of the 'daterange' field type.
+ *
+ * @FieldType(
+ *   id = "daterange",
+ *   label = @Translation("Date range"),
+ *   description = @Translation("Create and store date ranges."),
+ *   default_widget = "daterange_default",
+ *   default_formatter = "daterange_default",
+ *   list_class = "\Drupal\datetime_range\Plugin\Field\FieldType\DateRangeFieldItemList"
+ * )
+ */
+class DateRangeItem extends DateTimeItem {
+
+  /**
+   * Value for the 'datetime_type' setting: store a date and time.
+   */
+  const DATETIME_TYPE_ALLDAY = 'allday';
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
+    $properties['value'] = DataDefinition::create('datetime_iso8601')
+      ->setLabel(t('Start date value'))
+      ->setRequired(TRUE);
+
+    $properties['start_date'] = DataDefinition::create('any')
+      ->setLabel(t('Computed start date'))
+      ->setDescription(t('The computed start DateTime object.'))
+      ->setComputed(TRUE)
+      ->setClass(DateTimeComputed::class)
+      ->setSetting('date source', 'value');
+
+    $properties['end_value'] = DataDefinition::create('datetime_iso8601')
+      ->setLabel(t('End date value'))
+      ->setRequired(TRUE);
+
+    $properties['end_date'] = DataDefinition::create('any')
+      ->setLabel(t('Computed end date'))
+      ->setDescription(t('The computed end DateTime object.'))
+      ->setComputed(TRUE)
+      ->setClass(DateTimeComputed::class)
+      ->setSetting('date source', 'end_value');
+
+    return $properties;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function schema(FieldStorageDefinitionInterface $field_definition) {
+    $schema = parent::schema($field_definition);
+
+    $schema['columns']['value']['description'] = 'The start date value.';
+
+    $schema['columns']['end_value'] = [
+      'description' => 'The end date value.',
+    ] + $schema['columns']['value'];
+
+    $schema['indexes']['end_value'] = ['end_value'];
+
+    return $schema;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function storageSettingsForm(array &$form, FormStateInterface $form_state, $has_data) {
+    $element = parent::storageSettingsForm($form, $form_state, $has_data);
+
+    $element['datetime_type']['#options'][static::DATETIME_TYPE_ALLDAY] = $this->t('All Day');
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function generateSampleValue(FieldDefinitionInterface $field_definition) {
+    $type = $field_definition->getSetting('datetime_type');
+
+    // Just pick a date in the past year. No guidance is provided by this Field
+    // type.
+    $start = REQUEST_TIME - mt_rand(0, 86400 * 365) - 86400;
+    $end = $start + 86400;
+    if ($type == static::DATETIME_TYPE_DATETIME) {
+      $values['value'] = gmdate(DATETIME_DATETIME_STORAGE_FORMAT, $start);
+      $values['end_value'] = gmdate(DATETIME_DATETIME_STORAGE_FORMAT, $end);
+    }
+    else {
+      $values['value'] = gmdate(DATETIME_DATE_STORAGE_FORMAT, $start);
+      $values['end_value'] = gmdate(DATETIME_DATE_STORAGE_FORMAT, $end);
+    }
+    return $values;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isEmpty() {
+    $start_value = $this->get('value')->getValue();
+    $end_value = $this->get('end_value')->getValue();
+    return ($start_value === NULL || $start_value === '') && ($end_value === NULL || $end_value === '');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function onChange($property_name, $notify = TRUE) {
+    // Enforce that the computed date is recalculated.
+    if ($property_name == 'value') {
+      $this->start_date = NULL;
+    }
+    elseif ($property_name == 'end_value') {
+      $this->end_date = NULL;
+    }
+    parent::onChange($property_name, $notify);
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeDatelistWidget.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldWidget;
+
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime_range\Plugin\Field\FieldType\DateRangeItem;
+
+/**
+ * Plugin implementation of the 'daterange_datelist' widget.
+ *
+ * @FieldWidget(
+ *   id = "daterange_datelist",
+ *   label = @Translation("Select list"),
+ *   field_types = {
+ *     "daterange"
+ *   }
+ * )
+ */
+class DateRangeDatelistWidget extends DateRangeWidgetBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'increment' => '15',
+      'date_order' => 'YMD',
+      'time_type' => '24',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
+    $element = parent::formElement($items, $delta, $element, $form, $form_state);
+
+    $date_order = $this->getSetting('date_order');
+
+    if ($this->getFieldSetting('datetime_type') == DateRangeItem::DATETIME_TYPE_DATETIME) {
+      $time_type = $this->getSetting('time_type');
+      $increment = $this->getSetting('increment');
+    }
+    else {
+      $time_type = '';
+      $increment = '';
+    }
+
+    // Set up the date part order array.
+    switch ($date_order) {
+      default:
+      case 'YMD':
+        $date_part_order = ['year', 'month', 'day'];
+        break;
+
+      case 'MDY':
+        $date_part_order = ['month', 'day', 'year'];
+        break;
+
+      case 'DMY':
+        $date_part_order = ['day', 'month', 'year'];
+        break;
+    }
+    switch ($time_type) {
+      case '24':
+        $date_part_order = array_merge($date_part_order, ['hour', 'minute']);
+        break;
+
+      case '12':
+        $date_part_order = array_merge($date_part_order, ['hour', 'minute', 'ampm']);
+        break;
+
+      case 'none':
+        break;
+    }
+
+    $element['value'] = [
+      '#type' => 'datelist',
+      '#date_increment' => $increment,
+      '#date_part_order' => $date_part_order,
+    ] + $element['value'];
+
+    $element['end_value'] = [
+      '#type' => 'datelist',
+      '#date_increment' => $increment,
+      '#date_part_order' => $date_part_order,
+    ] + $element['end_value'];
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    $element = parent::settingsForm($form, $form_state);
+
+    $element['date_order'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Date part order'),
+      '#default_value' => $this->getSetting('date_order'),
+      '#options' => ['MDY' => $this->t('Month/Day/Year'), 'DMY' => $this->t('Day/Month/Year'), 'YMD' => $this->t('Year/Month/Day')],
+    ];
+
+    if ($this->getFieldSetting('datetime_type') == DateRangeItem::DATETIME_TYPE_DATETIME) {
+      $element['time_type'] = [
+        '#type' => 'select',
+        '#title' => $this->t('Time type'),
+        '#default_value' => $this->getSetting('time_type'),
+        '#options' => ['24' => $this->t('24 hour time'), '12' => $this->t('12 hour time')],
+      ];
+
+      $element['increment'] = [
+        '#type' => 'select',
+        '#title' => $this->t('Time increments'),
+        '#default_value' => $this->getSetting('increment'),
+        '#options' => [
+          1 => $this->t('1 minute'),
+          5 => $this->t('5 minute'),
+          10 => $this->t('10 minute'),
+          15 => $this->t('15 minute'),
+          30 => $this->t('30 minute'),
+        ],
+      ];
+    }
+    else {
+      $element['time_type'] = [
+        '#type' => 'hidden',
+        '#value' => 'none',
+      ];
+
+      $element['increment'] = [
+        '#type' => 'hidden',
+        '#value' => $this->getSetting('increment'),
+      ];
+    }
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = [];
+
+    $summary[] = $this->t('Date part order: @order', ['@order' => $this->getSetting('date_order')]);
+    if ($this->getFieldSetting('datetime_type') == DateRangeItem::DATETIME_TYPE_DATETIME) {
+      $summary[] = $this->t('Time type: @time_type', ['@time_type' => $this->getSetting('time_type')]);
+      $summary[] = $this->t('Time increments: @increment', ['@increment' => $this->getSetting('increment')]);
+    }
+
+    return $summary;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeDefaultWidget.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldWidget;
+
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\datetime_range\Plugin\Field\FieldType\DateRangeItem;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Plugin implementation of the 'daterange_default' widget.
+ *
+ * @FieldWidget(
+ *   id = "daterange_default",
+ *   label = @Translation("Date and time range"),
+ *   field_types = {
+ *     "daterange"
+ *   }
+ * )
+ */
+class DateRangeDefaultWidget extends DateRangeWidgetBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The date format storage.
+   *
+   * @var \Drupal\Core\Entity\EntityStorageInterface
+   */
+  protected $dateStorage;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, array $third_party_settings, EntityStorageInterface $date_storage) {
+    parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $third_party_settings);
+
+    $this->dateStorage = $date_storage;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $plugin_id,
+      $plugin_definition,
+      $configuration['field_definition'],
+      $configuration['settings'],
+      $configuration['third_party_settings'],
+      $container->get('entity_type.manager')->getStorage('date_format')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
+    $element = parent::formElement($items, $delta, $element, $form, $form_state);
+
+    // Identify the type of date and time elements to use.
+    switch ($this->getFieldSetting('datetime_type')) {
+      case DateRangeItem::DATETIME_TYPE_DATE:
+      case DateRangeItem::DATETIME_TYPE_ALLDAY:
+        $date_type = 'date';
+        $time_type = 'none';
+        $date_format = $this->dateStorage->load('html_date')->getPattern();
+        $time_format = '';
+        break;
+
+      default:
+        $date_type = 'date';
+        $time_type = 'time';
+        $date_format = $this->dateStorage->load('html_date')->getPattern();
+        $time_format = $this->dateStorage->load('html_time')->getPattern();
+        break;
+    }
+
+    $element['value'] += [
+      '#date_date_format' => $date_format,
+      '#date_date_element' => $date_type,
+      '#date_date_callbacks' => [],
+      '#date_time_format' => $time_format,
+      '#date_time_element' => $time_type,
+      '#date_time_callbacks' => [],
+    ];
+
+    $element['end_value'] += [
+      '#date_date_format' => $date_format,
+      '#date_date_element' => $date_type,
+      '#date_date_callbacks' => [],
+      '#date_time_format' => $time_format,
+      '#date_time_element' => $time_type,
+      '#date_time_callbacks' => [],
+    ];
+
+    return $element;
+  }
+
+}

core/modules/datetime_range/src/Plugin/Field/FieldWidget/DateRangeWidgetBase.php

+<?php
+
+namespace Drupal\datetime_range\Plugin\Field\FieldWidget;
+
+use Drupal\Core\Datetime\DrupalDateTime;
+use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
+use Drupal\datetime\Plugin\Field\FieldWidget\DateTimeWidgetBase;
+use Drupal\datetime_range\Plugin\Field\FieldType\DateRangeItem;
+
+/**
+ * Base class for the 'daterange_*' widgets.
+ */
+class DateRangeWidgetBase extends DateTimeWidgetBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
+    $element = parent::formElement($items, $delta, $element, $form, $form_state);
+    $element['#element_validate'][] = [$this, 'validateStartEnd'];
+    $element['value']['#title'] = $this->t('Start');
+
+    $element['end_value'] = [
+      '#title' => $this->t('End'),
+    ] + $element['value'];
+
+    if ($items[$delta]->start_date) {
+      /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+      $start_date = $items[$delta]->start_date;
+      $element['value']['#default_value'] = $this->createDefaultValue($start_date, $element['value']['#date_timezone']);
+    }
+
+    if ($items[$delta]->end_date) {
+      /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
+      $end_date = $items[$delta]->end_date;
+      $element['end_value']['#default_value'] = $this->createDefaultValue($end_date, $element['end_value']['#date_timezone']);
+    }
+
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function massageFormValues(array $values, array $form, FormStateInterface $form_state) {
+    // The widget form element type has transformed the value to a
+    // DrupalDateTime object at this point. We need to convert it back to the
+    // storage timezone and format.
+    foreach ($values as &$item) {
+      if (!empty($item['value']) && $item['value'] instanceof DrupalDateTime) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $start_date */
+        $start_date = $item['value'];
+        switch ($this->getFieldSetting('datetime_type')) {
+          case DateRangeItem::DATETIME_TYPE_DATE:
+            // If this is a date-only field, set it to the default time so the
+            // timezone conversion can be reversed.
+            datetime_date_default_time($start_date);
+            $format = DATETIME_DATE_STORAGE_FORMAT;
+            break;
+
+          case DateRangeItem::DATETIME_TYPE_ALLDAY:
+            // All day fields start at midnight on the starting date, but are
+            // stored like datetime fields, so we need to adjust the time.
+            // This function is called twice, so to prevent a double conversion
+            // we need to explicitly set the timezone.
+            $start_date->setTimeZone(timezone_open(drupal_get_user_timezone()));
+            $start_date->setTime(0, 0, 0);
+            $format = DATETIME_DATETIME_STORAGE_FORMAT;
+            break;
+
+          default:
+            $format = DATETIME_DATETIME_STORAGE_FORMAT;
+            break;
+        }
+        // Adjust the date for storage.
+        $start_date->setTimezone(new \DateTimezone(DATETIME_STORAGE_TIMEZONE));
+        $item['value'] = $start_date->format($format);
+      }
+
+      if (!empty($item['end_value']) && $item['end_value'] instanceof DrupalDateTime) {
+        /** @var \Drupal\Core\Datetime\DrupalDateTime $end_date */
+        $end_date = $item['end_value'];
+        switch ($this->getFieldSetting('datetime_type')) {
+          case DateRangeItem::DATETIME_TYPE_DATE:
+            // If this is a date-only field, set it to the default time so the
+            // timezone conversion can be reversed.
+            datetime_date_default_time($end_date);
+            $format = DATETIME_DATE_STORAGE_FORMAT;
+            break;
+
+          case DateRangeItem::DATETIME_TYPE_ALLDAY:
+            // All day fields end at midnight on the end date, but are
+            // stored like datetime fields, so we need to adjust the time.
+            // This function is called twice, so to prevent a double conversion
+            // we need to explicitly set the timezone.
+            $end_date->setTimeZone(timezone_open(drupal_get_user_timezone()));
+            $end_date->setTime(23, 59, 59);
+            $format = DATETIME_DATETIME_STORAGE_FORMAT;
+            break;
+
+          default:
+            $format = DATETIME_DATETIME_STORAGE_FORMAT;
+            break;
+        }
+        // Adjust the date for storage.
+        $end_date->setTimezone(new \DateTimezone(DATETIME_STORAGE_TIMEZONE));
+        $item['end_value'] = $end_date->format($format);
+      }
+    }
+
+    return $values;
+  }
+
+  /**
+   * #element_validate callback to ensure that the start date <= the end date.
+   *
+   * @param array $element
+   *   An associative array containing the properties and children of the
+   *   generic form element.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *   The current state of the form.
+   * @param array $complete_form
+   *   The complete form structure.
+   */
+  public function validateStartEnd(array &$element, FormStateInterface $form_state, array &$complete_form) {
+    $start_date = $element['value']['#value']['object'];
+    $end_date = $element['end_value']['#value']['object'];
+
+    if ($start_date instanceof DrupalDateTime && $end_date instanceof DrupalDateTime) {
+      if ($start_date->format('U') !== $end_date->format('U')) {
+        $interval = $start_date->diff($end_date);
+        if ($interval->invert === 1) {
+          $form_state->setError($element, $this->t('The @title end date cannot be before the start date', ['@title' => $element['#title']]));
+        }
+      }
+    }
+  }
+
+  /**
+   * Creates a date object for use as a default value.
+   *
+   * This will take a default value, apply the proper timezone for display in
+   * a widget, and set the default time for date-only fields.
+   *
+   * @param \Drupal\Core\Datetime\DrupalDateTime $date
+   *   The UTC default date.
+   * @param string $timezone
+   *   The timezone to apply.
+   *
+   * @return \Drupal\Core\Datetime\DrupalDateTime
+   *   A date object for use as a default value in a field widget.
+   */
+  protected function createDefaultValue($date, $timezone) {
+    // The date was created and verified during field_load(), so it is safe to
+    // use without further inspection.
+    if ($this->getFieldSetting('datetime_type') == DateTimeItem::DATETIME_TYPE_DATE) {
+      // A date without time will pick up the current time, use the default
+      // time.
+      datetime_date_default_time($date);
+    }
+    $date->setTimezone(new \DateTimeZone($timezone));
+    return $date;
+  }
+
+}