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Diffstat (limited to 'railties/doc/guides/html/activerecord_validations_callbacks.html')
| -rw-r--r-- | railties/doc/guides/html/activerecord_validations_callbacks.html | 96 |
1 files changed, 48 insertions, 48 deletions
diff --git a/railties/doc/guides/html/activerecord_validations_callbacks.html b/railties/doc/guides/html/activerecord_validations_callbacks.html index be556283c1..2153979d7b 100644 --- a/railties/doc/guides/html/activerecord_validations_callbacks.html +++ b/railties/doc/guides/html/activerecord_validations_callbacks.html @@ -236,7 +236,7 @@ Using validation directly in your Active Record classes ensures that only valid <h3 id="_when_does_validation_happen">1.2. When Does Validation Happen?</h3>
<div class="paragraph"><p>There are two kinds of Active Record objects: those that correspond to a row inside your database and those that do not. When you create a fresh object, using the <tt>new</tt> method, that object does not belong to the database yet. Once you call <tt>save</tt> upon that object it will be saved into the appropriate database table. Active Record uses the <tt>new_record?</tt> instance method to determine whether an object is already in the database or not. Consider the following simple Active Record class:</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -274,7 +274,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_acceptance_of_tt_helper">2.1. The <tt>validates_acceptance_of</tt> helper</h3>
<div class="paragraph"><p>Validates that a checkbox on the user interface was checked when a form was submitted. This is normally used when the user needs to agree to your application’s terms of service, confirm reading some text, or any similar concept. This validation is very specific to web applications and actually this <em>acceptance</em> does not need to be recorded anywhere in your database (if you don’t have a field for it, the helper will just create a virtual attribute).</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -284,7 +284,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>The default error message for <tt>validates_acceptance_of</tt> is "<em>must be accepted</em>"</p></div>
<div class="paragraph"><p><tt>validates_acceptance_of</tt> can receive an <tt>:accept</tt> option, which determines the value that will be considered acceptance. It defaults to "1", but you can change this.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -294,7 +294,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_associated_tt_helper">2.2. The <tt>validates_associated</tt> helper</h3>
<div class="paragraph"><p>You should use this helper when your model has associations with other models and they also need to be validated. When you try to save your object, <tt>valid?</tt> will be called upon each one of the associated objects.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -315,7 +315,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_confirmation_of_tt_helper">2.3. The <tt>validates_confirmation_of</tt> helper</h3>
<div class="paragraph"><p>You should use this helper when you have two text fields that should receive exactly the same content. For example, you may want to confirm an email address or a password. This validation creates a virtual attribute, using the name of the field that has to be confirmed with <em>_confirmation</em> appended.</p></div>
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+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -324,7 +324,7 @@ http://www.gnu.org/software/src-highlite --> <span style="font-weight: bold"><span style="color: #0000FF">end</span></span></tt></pre></div></div>
<div class="paragraph"><p>In your view template you could use something like</p></div>
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@@ -339,7 +339,7 @@ http://www.gnu.org/software/src-highlite --> </tr></table>
</div>
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+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -351,7 +351,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_exclusion_of_tt_helper">2.4. The <tt>validates_exclusion_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates that the attributes' values are not included in a given set. In fact, this set can be any enumerable object.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -364,7 +364,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_format_of_tt_helper">2.5. The <tt>validates_format_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates the attributes' values by testing whether they match a given pattern. This pattern must be specified using a Ruby regular expression, which is specified using the <tt>:with</tt> option.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -376,7 +376,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_inclusion_of_tt_helper">2.6. The <tt>validates_inclusion_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates that the attributes' values are included in a given set. In fact, this set can be any enumerable object.</p></div>
<div class="listingblock">
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+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
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@@ -389,7 +389,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_length_of_tt_helper">2.7. The <tt>validates_length_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates the length of your attribute’s value. It includes a variety of different options, so you can specify length constraints in different ways:</p></div>
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@@ -424,7 +424,7 @@ http://www.gnu.org/software/src-highlite --> </ul></div>
<div class="paragraph"><p>The default error messages depend on the type of length validation being performed. You can personalize these messages, using the <tt>:wrong_length</tt>, <tt>:too_long</tt> and <tt>:too_short</tt> options and the <tt>%d</tt> format mask as a placeholder for the number corresponding to the length constraint being used. You can still use the <tt>:message</tt> option to specify an error message.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -436,7 +436,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>This helper validates that your attributes have only numeric values. By default, it will match an optional sign followed by a integral or floating point number. Using the <tt>:integer_only</tt> option set to true, you can specify that only integral numbers are allowed.</p></div>
<div class="paragraph"><p>If you set <tt>:integer_only</tt> to <tt>true</tt>, then it will use the <tt>$$/\A[</tt>\-]?\d+\Z/<tt> regular expression to validate the attribute’s value. Otherwise, it will try to convert the value to a number using +Kernel.Float</tt>.</p></div>
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+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -486,7 +486,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_presence_of_tt_helper">2.9. The <tt>validates_presence_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates that the specified attributes are not empty. It uses the <tt>blank?</tt> method to check if the value is either <tt>nil</tt> or an empty string (if the string has only spaces, it will still be considered empty).</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -502,7 +502,7 @@ http://www.gnu.org/software/src-highlite --> </tr></table>
</div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -522,7 +522,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_uniqueness_of_tt_helper">2.10. The <tt>validates_uniqueness_of</tt> helper</h3>
<div class="paragraph"><p>This helper validates that the attribute’s value is unique right before the object gets saved. It does not create a uniqueness constraint directly into your database, so it may happen that two different database connections create two records with the same value for a column that you intend to be unique. To avoid that, you must create an unique index in your database.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -532,7 +532,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>The validation happens by performing a SQL query into the model’s table, searching for a record where the attribute that must be validated is equal to the value in the object being validated.</p></div>
<div class="paragraph"><p>There is a <tt>:scope</tt> option that you can use to specify other attributes that are used to limit the uniqueness check:</p></div>
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@@ -542,7 +542,7 @@ http://www.gnu.org/software/src-highlite --> <span style="font-weight: bold"><span style="color: #0000FF">end</span></span></tt></pre></div></div>
<div class="paragraph"><p>There is also a <tt>:case_sensitive</tt> option that you can use to define whether the uniqueness constraint will be case sensitive or not. This option defaults to true.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -553,7 +553,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_validates_each_tt_helper">2.11. The <tt>validates_each</tt> helper</h3>
<div class="paragraph"><p>This helper validates attributes against a block. It doesn’t have a predefined validation function. You should create one using a block, and every attribute passed to <tt>validates_each</tt> will be tested against it. In the following example, we don’t want names and surnames to begin with lower case.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -570,7 +570,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_allow_nil_tt_option">3.1. The <tt>:allow_nil</tt> option</h3>
<div class="paragraph"><p>The <tt>:allow_nil</tt> option skips the validation when the value being validated is <tt>nil</tt>. You may be asking yourself if it makes any sense to use <tt>:allow_nil</tt> and <tt>validates_presence_of</tt> together. Well, it does. Remember, the validation will be skipped only for <tt>nil</tt> attributes, but empty strings are not considered <tt>nil</tt>.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -581,7 +581,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_the_tt_allow_blank_tt_option">3.2. The <tt>:allow_blank</tt> option</h3>
<div class="paragraph"><p>The <tt>:allow_blank: option is similar to the +:allow_nil</tt> option. This option will let validation pass if the attribute’s value is <tt>nil</tt> or an empty string, i.e., any value that returns <tt>true</tt> for <tt>blank?</tt>.</p></div>
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-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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http://www.gnu.org/software/src-highlite -->
@@ -596,7 +596,7 @@ Topic<span style="color: #990000">.</span>create<span style="color: #990000">(</ <h3 id="_the_tt_on_tt_option">3.4. The <tt>:on</tt> option</h3>
<div class="paragraph"><p>The <tt>:on</tt> option lets you specify when the validation should happen. The default behavior for all the built-in validation helpers is to be ran on save (both when you’re creating a new record and when you’re updating it). If you want to change it, you can use <tt>:on => :create</tt> to run the validation only when a new record is created or <tt>:on => :update</tt> to run the validation only when a record is updated.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
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@@ -617,7 +617,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_using_a_symbol_with_the_tt_if_tt_and_tt_unless_tt_options">4.1. Using a symbol with the <tt>:if</tt> and <tt>:unless</tt> options</h3>
<div class="paragraph"><p>You can associate the <tt>:if</tt> and <tt>:unless</tt> options with a symbol corresponding to the name of a method that will get called right before validation happens. This is the most commonly used option.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -631,7 +631,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_using_a_string_with_the_tt_if_tt_and_tt_unless_tt_options">4.2. Using a string with the <tt>:if</tt> and <tt>:unless</tt> options</h3>
<div class="paragraph"><p>You can also use a string that will be evaluated using <tt>:eval</tt> and needs to contain valid Ruby code. You should use this option only when the string represents a really short condition.</p></div>
<div class="listingblock">
-<div class="content"><!-- Generator: GNU source-highlight 2.9
+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
@@ -641,7 +641,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_using_a_proc_object_with_the_tt_if_tt_and_tt_unless_tt_options">4.3. Using a Proc object with the <tt>:if</tt> and :<tt>unless</tt> options</h3>
<div class="paragraph"><p>Finally, it’s possible to associate <tt>:if</tt> and <tt>:unless</tt> with a Ruby Proc object which will be called. Using a Proc object can give you the hability to write a condition that will be executed only when the validation happens and not when your code is loaded by the Ruby interpreter. This option is best suited when writing short validation methods, usually one-liners.</p></div>
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@@ -654,7 +654,7 @@ http://www.gnu.org/software/src-highlite --> <div class="sectionbody">
<div class="paragraph"><p>When the built-in validation helpers are not enough for your needs, you can write your own validation methods. You can do that by implementing methods that verify the state of your models and add messages to their <tt>errors</tt> collection when they are invalid. You must then register those methods by using one or more of the <tt>validate</tt>, <tt>validate_on_create</tt> or <tt>validate_on_update</tt> class methods, passing in the symbols for the validation methods' names. You can pass more than one symbol for each class method and the respective validations will be ran in the same order as they were registered.</p></div>
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@@ -674,7 +674,7 @@ http://www.gnu.org/software/src-highlite --> <span style="font-weight: bold"><span style="color: #0000FF">end</span></span></tt></pre></div></div>
<div class="paragraph"><p>You can even create your own validation helpers and reuse them in several different models. Here is an example where we create a custom validation helper to validate the format of fields that represent email addresses:</p></div>
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<div class="paragraph"><p>The recipe is simple: just create a new validation method inside the <tt>ActiveRecord::Validations::ClassMethods</tt> module. You can put this code in a file inside your application’s <strong>lib</strong> folder, and then requiring it from your <strong>environment.rb</strong> or any other file inside <strong>config/initializers</strong>. You can use this helper like this:</p></div>
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</ul></div>
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@@ -763,7 +763,7 @@ person<span style="color: #990000">.</span>invalid?<span style="color: #990000"> </li>
</ul></div>
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@@ -793,7 +793,7 @@ person<span style="color: #990000">.</span>errors<span style="color: #990000">.< </li>
</ul></div>
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+<div class="content"><!-- Generator: GNU source-highlight 2.11.1
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@@ -817,7 +817,7 @@ p<span style="color: #990000">.</span>errors<span style="color: #990000">.</span <div class="sectionbody">
<div class="paragraph"><p>Rails provides built-in helpers to display the error messages of your models in your view templates. When creating a form with the form_for helper, you can use the error_messages method on the form builder to render all failed validation messages for the current model instance.</p></div>
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by Lorenzo Bettini
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@@ -898,7 +898,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_changing_the_way_form_fields_with_errors_are_displayed">7.1. Changing the way form fields with errors are displayed</h3>
<div class="paragraph"><p>By default, form fields with errors are displayed enclosed by a <tt>div</tt> element with the <tt>fieldWithErrors</tt> CSS class. However, we can write some Ruby code to override the way Rails treats those fields by default. Here is a simple example where we change the Rails behaviour to always display the error messages in front of each of the form fields with errors. The error messages will be enclosed by a <tt>span</tt> element with a <tt>validation-error</tt> CSS class. There will be no <tt>div</tt> element enclosing the <tt>input</tt> element, so we get rid of that red border around the text field. You can use the <tt>validation-error</tt> CSS class to style it anyway you want.</p></div>
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by Lorenzo Bettini
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@@ -937,7 +937,7 @@ An object of the <tt>ActionView::Helpers::InstanceTag</tt> class. <h3 id="_callbacks_registration">8.1. Callbacks registration</h3>
<div class="paragraph"><p>In order to use the available callbacks, you need to registrate them. You can do that by implementing them as an ordinary methods, and then using a macro-style class method to register then as callbacks.</p></div>
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@@ -955,7 +955,7 @@ http://www.gnu.org/software/src-highlite --> <span style="font-weight: bold"><span style="color: #0000FF">end</span></span></tt></pre></div></div>
<div class="paragraph"><p>The macro-style class methods can also receive a block. Rails best practices say that you should only use this style of registration if the code inside your block is so short that it fits in just one line.</p></div>
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@@ -979,7 +979,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_using_a_symbol_with_the_tt_if_tt_and_tt_unless_tt_options_2">9.1. Using a symbol with the <tt>:if</tt> and <tt>:unless</tt> options</h3>
<div class="paragraph"><p>You can associate the <tt>:if</tt> and <tt>:unless</tt> options with a symbol corresponding to the name of a method that will get called right before the callback. If this method returns <tt>false</tt> the callback won’t be executed. This is the most common option. Using this form of registration it’s also possible to register several different methods that should be called to check the if the callback should be executed.</p></div>
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<div class="paragraph"><p>You can also use a string that will be evaluated using <tt>:eval</tt> and needs to contain valid Ruby code. You should use this option only when the string represents a really short condition.</p></div>
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@@ -999,7 +999,7 @@ http://www.gnu.org/software/src-highlite --> <h3 id="_using_a_proc_object_with_the_tt_if_tt_and_tt_unless_tt_options_2">9.3. Using a Proc object with the <tt>:if</tt> and :<tt>unless</tt> options</h3>
<div class="paragraph"><p>Finally, it’s possible to associate <tt>:if</tt> and <tt>:unless</tt> with a Ruby Proc object. This option is best suited when writing short validation methods, usually one-liners.</p></div>
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<div class="paragraph"><p>When writing conditional callbacks, it’s possible to mix both <tt>:if</tt> and <tt>:unless</tt> in the same callback declaration.</p></div>
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@@ -1139,7 +1139,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>Sometimes the callback methods that you’ll write will be useful enough to be reused at other models. Active Record makes it possible to create classes that encapsulate the callback methods, so it becomes very easy to reuse them.</p></div>
<div class="paragraph"><p>Here’s an example where we create a class with a after_destroy callback for a PictureFile model.</p></div>
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<div class="paragraph"><p>When declared inside a class the callback method will receive the model object as a parameter. We can now use it this way:</p></div>
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<div class="paragraph"><p>Note that we needed to instantiate a new PictureFileCallbacks object, since we declared our callback as an instance method. Sometimes it will make more sense to have it as a class method.</p></div>
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<div class="paragraph"><p>If the callback method is declared this way, it won’t be necessary to instantiate a PictureFileCallbacks object.</p></div>
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@@ -1186,7 +1186,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>Observer classes are subclasses of the ActiveRecord::Observer class. When this class is subclassed, Active Record will look at the name of the new class and then strip the <em>Observer</em> part to find the name of the Active Record class to observe.</p></div>
<div class="paragraph"><p>Consider a Registration model, where we want to send an email every time a new registration is created. Since sending emails is not directly related to our model’s purpose, we could create an Observer to do just that:</p></div>
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@@ -1198,7 +1198,7 @@ http://www.gnu.org/software/src-highlite --> <div class="paragraph"><p>Like in callback classes, the observer’s methods receive the observed model as a parameter.</p></div>
<div class="paragraph"><p>Sometimes using the ModelName + Observer naming convention won’t be the best choice, mainly when you want to use the same observer for more than one model class. It’s possible to explicity specify the models that our observer should observe.</p></div>
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<div class="paragraph"><p>If you paid attention, you may be wondering where Active Record Observers are referenced in our applications, so they get instantiated and begin to interact with our models. For observers to work we need to register them somewhere. The usual place to do that is in our application’s <strong>config/environment.rb</strong> file. In this file there is a commented-out line where we can define the observers that our application should load at start-up.</p></div>
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