Improve the readme file.

README.md

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 [![Build Status](https://travis-ci.org/Gizra/entity_validator.svg?branch=7.x-1.x)](https://travis-ci.org/Gizra/entity_validator)
 
 # Entity Validator
+The entity validator try to solve a simple problem in Drupal 7: validate the
+entity object before it's written into the DB. That problem solved in Drupal 8
+due to the OOP approach and the understanding that the written data to the DB
+need to be valid.
 
-Programmatically validate entities.
+The first thought that cross your mind is: "When i submit a node's form i get
+errors. What's the problem?". The problem is that the validation process done at
+the form level. If you take for example the feeds module you can understand the
+issue a little bit more: feeds can create nodes without titles. This is wrong
+since the node's title is a required field.
+
+## The basics
+*All the examples are taken from the entity validator example module.*
+
+You'll first need to declare a ctools plugin directory for your module:
+```php
+/**
+ * Implements hook_ctools_plugin_directory().
+ */
+function entity_validator_example_ctools_plugin_directory($module, $plugin) {
+  if ($module == 'entity_validator') {
+    return 'plugins/' . $plugin;
+  }
+}
+
+```
+
+After that you'll need to create the next files structure:
+
+|- validator
+
+|-- *entity_type*
+
+|---- *entity_bundle*
+
+|------ *entity_type*__*entity_bundle*.inc
+
+|------ *name_of_class*.class.php
+
+If we look on the entity_validator_example module you'll see a file called
+*node__article.inc*
+```php
+$plugin = array(
+  'label' => t('Article'),
+  'description' => t('Validate the article content type.'),
+  'entity_type' => 'node',
+  'bundle' => 'article',
+  'class' => 'EntityValidatorExampleArticleValidator',
+);
+
+```
+This is a validator for a node article. The validator handler,
+*EntityValidatorExampleArticleValidator*, is in the file
+*EntityValidatorExampleArticleValidator.class.php*.
+
+## Start validating
+After defining the validator handler we can start and set the methods:
+```php
+  /**
+   * Overrides EntityValidateBase::getFieldsInfo().
+   */
+  public function getFieldsInfo() {
+    $fields = parent::getFieldsInfo();
+
+    $fields['title']['validators'][] = 'validateTitleText';
+    $fields['body']['validators'][] = 'validateBodyText';
+
+    return $fields;
+  }
+```
+
+The method defines the fields and properties handlers. There are two type of
+handlers:
+  - Validator - You'll set errors according to the value the field/property
+  have.
+  - Pre-process - Although this is not in use, you can change the field/property
+    value.
+
+The next example set validators to the title property and the body field.
+Although required fields or mandatory properties are automatically checked for
+not being empty, the example module add another validators as a proof of
+concept:
+```php
+  /**
+   * Validate the title is at least 3 characters long.
+   */
+  public function validateTitleText($field_name, $value) {
+    if (strlen($value) < 3) {
+      $this->setError($field_name, 'The @field should be at least 3 characters long.');
+    }
+  }
+
+  /**
+   * Validate the description has the word "Gizra".
+   */
+  public function validateBodyText($field_name, $value) {
+    if (empty($value['value']) || strpos($value['value'], 'Drupal') === FALSE) {
+      $this->setError($field_name, 'The @field should have the word "Drupal".');
+    }
+  }
+```
+
+The *validateTitleText* method checking the length of the string.
+You can see that the text we set as an error did not passed through t(). That's
+correct. When displaying the errors to the user, by default, the text will
+passed through t(). We'll get to this part later.
+
+Another handler type is the pre-process handler:
+```php
+  /**
+   * Overrides EntityValidateBase::getFieldsInfo().
+   */
+  public function getFieldsInfo() {
+    $fields = parent::getFieldsInfo();
+
+    $fields['title']['preprocess'][] = 'preprocessTitleText';
+
+    return $fields;
+  }
+
+  /**
+   * Altering the title of the node.
+   */
+  public function preprocessTitleText($field_name, $value) {
+    return 'This is a new title';
+  }
+```
+
+## Interact with the entity validator
+Validating an object is pretty easy. First initialize the handler:
+```php
+$handler = entity_validator_get_validator_handler('node', 'article');
+```
+
+You can validate an object in three ways:
+1. With exceptions:
+```php
+$handler->validate($node);
+```
+If there any errors set by the methods they will be thrown as an exception.
+
+2. If you just want to see if there any error, without getting exceptions, you
+can use a silent mode:
+
+```php
+  $result = $handler->validate($node, TRUE);
+  if ($result) {
+    drupal_set_message(t('Validate in silent mode did not throw an exception.'), 'error');
+  }
+```
+The $result will be a boolean variable.
+
+3. You can handle the errors by your self. You'll need first to validate the
+object in a silent way, exactly like in 2. You can get the errors squashed - all
+the placeholders from the errors replaced by the real value, i.e: @field
+replaced with the name of the field:
+
+```php
+    $result = $handler->validate($node, TRUE);
+    if ($result) {
+      $params['errors'] = $handler->getErrors(TRUE);
+      drupal_set_message(t('Validate in silent mode did not throw an exception but there are some errors: !errors', $params), 'error');
+    }
+
+```
+
+You can get the errors without being squashed. This will return an array in the
+next format:
+```php
+    $result = $handler->getErrors(FALSE);
+    $expected_result = array(
+      'title' => array(
+        array(
+          'message' => 'The field @field cannot be empty.',
+          'params' => array(
+            '@field' => 'title',
+          ),
+        ),
+        array(
+          'message' => 'The @field should be at least 3 characters long.',
+          'params' => array(
+            '@field' => 'title',
+          ),
+        ),
+      ),
+    );
+```
+This is useful when you want to handle the placeholders by your self, similar to
+the [Restful](http://github.com/gizra/restful) module.
 
 ## Credits