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"\nDrupal 8 comes with plenty of new features: the high visibility ones, like CKEditor or Views in core, and those less obvious but equally pivotal to Drupal 8’s strength and flexibility, like the Entity Validation API.\n\nNever heard of it? You're not alone – much of the fanfare around Drupal 8 is devoted to the shiny parts. But under the hood, rock solid developer APIs like the Entity Validation API are what will make Drupal 8 a pleasure to work with for client projects and contributed modules alike.\n\nSo what is this Entity Validation API and why should you care?\nFor Those Who Came in Late\nIn Drupal versions up to and including Drupal 7, any validation was done in the Form API. Consider the Comment entity, provided by the Comment module. There is a lot of validation relating to comments, such as:\n\n \tIf the comment is being updated, we confirm the timestamp is a valid date.\n \tIf the comment is being updated and the username is changed, we confirm the username is valid.\n \tIf the comment is anonymous, we validate that the name used for the comment doesn't match an existing username.\n \tIf the comment is anonymous, we confirm that the e-mail address entered is valid.\n \tIf the comment is anonymous, we confirm that the homepage is a valid URL.\n\nIn Drupal 7 and earlier all of this happens in the comment form validation logic, in comment_form_validate().\n\nThe issue here is that this validation is tied to a form submission. If you're saving a comment via some other method, then you have to duplicate all this logic to ensure you don’t end up with invalid comment entities. Common alternate methods include:\n\n \tusing Rules;\n \tusing a Restful, Services, or Rest WS endpoint;\n \tprogrammatically saving via custom code;\n \tusing a custom comment form.\n\nThe same scenario is repeated for Nodes, Users, Taxonomy terms, and custom Blocks (which aren’t entities per se in Drupal 7, but the story is the same).\nIt’s Like an Onion, or Maybe a Layer Cake\nBut before we can talk about Drupal 8's Entity Validation API, we need to go over some background on the Entity API itself.\n\nIn Drupal 7, entities are \\StdClassobjects; accessing field values depends on the entity and the field. There is no real unification. For example, $node-&gt;title is a string, while $node-&gt;field_tags is an array.\n\nAnd so, in Drupal 7 you might see things like this:\n$node-&gt;field_make_it_stop['LANGUAGE_NONE'][0]['wtf_bbq'];\n\nIn Drupal 8, the Entity Field API brings unified access to field properties and first-class objects for each entity type. So in Drupal 8, you see consistency like this:\n$node-&gt;field_rainbows-&gt;value;\n$node-&gt;title-&gt;value;\n\nWhen you work with fields and entities in Drupal 8, you’re likely to interact with a suite of interfaces that comprise the API.\nKey Interfaces in Drupal 8 Entity Field API\nLet’s start with ContentEntityInterface, the overarching interface that content entities in Drupal 8 implement. (Node, Comment, Taxonomy Term, and BlockContent, among others, implement this interface.)\n\nEach field and each property on a content entity is an instance of FieldItemListInterface. Even fields like the node title are lists, which just contain a single value.\n\nEach FieldItemListInterface consists of one or more FieldItemInterface objects.\n\nAt the lowest level of the API, each FieldItemInterface is comprised of one or more DataDefinitionInterface objects that make up the properties or columns in each item value.\n\nView More 2001\nView More 2002\nView More 2003\nView More 2004\nView More 2005\nView More 2006\nView More 2007\nView More 2008\nView More 2009\nView More 2010\nView More 2011\nView More 2012\nView More 2013\nView More 2014\nView More 2015\nView More 2016\nView More 2017\nView More 2018\nView More 2019\nView More 2020\nView More 2021\nView More 2022\nView More 2023\nView More 2024\nView More 2025\nView More 2026\nView More 2027\nView More 2028\nView More 2029\nView More 2030\nView More 2031\nView More 2032\nView More 2033\nView More 2034\nView More 2035\nView More 2036\nView More 2037\nView More 2038\nView More 2039\nView More 2040\nView More 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<https://valuablenews.in/introducing-drupal-8s-entity-validation-api/>