src/classes/Enumerable.html

---
title: Enumerable
layout: default
---
<div class="main">
    <div class="banner">
        
            <span>Ruby on Rails 8.0.0</span><br />
        
        <div class="type">Module</div>
        <h1>
            Enumerable
            
        </h1>
        <ul class="files">
            
            <li><a href="../files/activesupport/lib/active_support/core_ext/enumerable_rb.html">activesupport/lib/active_support/core_ext/enumerable.rb</a></li>
            
            <li><a href="../files/activesupport/lib/active_support/core_ext/object/json_rb.html">activesupport/lib/active_support/core_ext/object/json.rb</a></li>
            
        </ul>
    </div>
    <div id="bodyContent">
        <div id="content">
  

    <h2 id="namespace">Namespace</h2>

    
      <h3 id="class">Class</h3>
      <ul>
      
        <li><a href="Enumerable/SoleItemExpectedError.html">Enumerable::SoleItemExpectedError</a></li>
      
      </ul>
    
  
    <h2 id="methods">Methods</h2>
    <ul>
      
        <li>
          <a href="#method-i-compact_blank">compact_blank</a>
        </li>
      
        <li>
          <a href="#method-i-exclude-3F">exclude?</a>
        </li>
      
        <li>
          <a href="#method-i-excluding">excluding</a>
        </li>
      
        <li>
          <a href="#method-i-in_order_of">in_order_of</a>
        </li>
      
        <li>
          <a href="#method-i-including">including</a>
        </li>
      
        <li>
          <a href="#method-i-index_by">index_by</a>
        </li>
      
        <li>
          <a href="#method-i-index_with">index_with</a>
        </li>
      
        <li>
          <a href="#method-i-many-3F">many?</a>
        </li>
      
        <li>
          <a href="#method-i-maximum">maximum</a>
        </li>
      
        <li>
          <a href="#method-i-minimum">minimum</a>
        </li>
      
        <li>
          <a href="#method-i-pick">pick</a>
        </li>
      
        <li>
          <a href="#method-i-pluck">pluck</a>
        </li>
      
        <li>
          <a href="#method-i-sole">sole</a>
        </li>
      
        <li>
          <a href="#method-i-without">without</a>
        </li>
      
    </ul>
  

    <!-- Methods -->
    
    
      <h2 id="instance-public-methods">Instance Public methods</h2>
      
        <div class="method">
          <h3 id="method-i-compact_blank">
            
              compact_blank()
            
          </h3>

          
            <div class="description">
              <p>Returns a new <code>Array</code> without the blank items. Uses <a href="Object.html#method-i-blank-3F"><code>Object#blank?</code></a> for determining if an item is blank.</p>

<pre><code>[1, &quot;&quot;, nil, 2, &quot; &quot;, [], {}, false, true].compact_blank
# =&gt;  [1, 2, true]

Set.new([nil, &quot;&quot;, 1, false]).compact_blank
# =&gt; [1]
</code></pre>

<p>When called on a <code>Hash</code>, returns a new <code>Hash</code> without the blank values.</p>

<pre><code>{ a: &quot;&quot;, b: 1, c: nil, d: [], e: false, f: true }.compact_blank
# =&gt; { b: 1, f: true }
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 184
  def compact_blank
    reject(&amp;:blank?)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L184" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-exclude-3F">
            
              exclude?(object)
            
          </h3>

          
            <div class="description">
              <p>The negative of the <code>Enumerable#include?</code>. Returns <code>true</code> if the collection does not include the object.</p>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 118
  def exclude?(object)
    !include?(object)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L118" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-excluding">
            
              excluding(*elements)
            
          </h3>

          
            <div class="description">
              <p>Returns a copy of the enumerable excluding the specified elements.</p>

<pre><code>[&quot;David&quot;, &quot;Rafael&quot;, &quot;Aaron&quot;, &quot;Todd&quot;].excluding &quot;Aaron&quot;, &quot;Todd&quot;
# =&gt; [&quot;David&quot;, &quot;Rafael&quot;]

[&quot;David&quot;, &quot;Rafael&quot;, &quot;Aaron&quot;, &quot;Todd&quot;].excluding %w[ Aaron Todd ]
# =&gt; [&quot;David&quot;, &quot;Rafael&quot;]

{foo: 1, bar: 2, baz: 3}.excluding :bar
# =&gt; {foo: 1, baz: 3}
</code></pre>
            </div>
          

            <div class="aka">
              Also aliased as: <a href="Enumerable.html#method-i-without">without</a>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 132
  def excluding(*elements)
    elements.flatten!(1)
    reject { |element| elements.include?(element) }
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L132" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-in_order_of">
            
              in_order_of(key, series, filter: true)
            
          </h3>

          
            <div class="description">
              <p>Returns a new <code>Array</code> where the order has been set to that provided in the <code>series</code>, based on the <code>key</code> of the objects in the original enumerable.</p>

<pre><code>[ Person.find(5), Person.find(3), Person.find(1) ].in_order_of(:id, [ 1, 5, 3 ])
# =&gt; [ Person.find(1), Person.find(5), Person.find(3) ]
</code></pre>

<p>If the <code>series</code> include keys that have no corresponding element in the <a href="Enumerable.html"><code>Enumerable</code></a>, these are ignored. If the <a href="Enumerable.html"><code>Enumerable</code></a> has additional elements that aren’t named in the <code>series</code>, these are not included in the result, unless the <code>filter</code> option is set to <code>false</code>.</p>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 197
  def in_order_of(key, series, filter: true)
    if filter
      group_by(&amp;key).values_at(*series).flatten(1).compact
    else
      sort_by { |v| series.index(v.public_send(key)) || series.size }.compact
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L197" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-including">
            
              including(*elements)
            
          </h3>

          
            <div class="description">
              <p>Returns a new array that includes the passed elements.</p>

<pre><code>[ 1, 2, 3 ].including(4, 5)
# =&gt; [ 1, 2, 3, 4, 5 ]

[&quot;David&quot;, &quot;Rafael&quot;].including %w[ Aaron Todd ]
# =&gt; [&quot;David&quot;, &quot;Rafael&quot;, &quot;Aaron&quot;, &quot;Todd&quot;]
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 112
  def including(*elements)
    to_a.including(*elements)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L112" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-index_by">
            
              index_by()
            
          </h3>

          
            <div class="description">
              <p>Convert an enumerable to a hash, using the block result as the key and the element as the value.</p>

<pre><code>people.index_by(&amp;:login)
# =&gt; { &quot;nextangle&quot; =&gt; &lt;Person ...&gt;, &quot;chade-&quot; =&gt; &lt;Person ...&gt;, ...}

people.index_by { |person| &quot;#{person.first_name} #{person.last_name}&quot; }
# =&gt; { &quot;Chade- Fowlersburg-e&quot; =&gt; &lt;Person ...&gt;, &quot;David Heinemeier Hansson&quot; =&gt; &lt;Person ...&gt;, ...}
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 52
  def index_by
    if block_given?
      result = {}
      each { |elem| result[yield(elem)] = elem }
      result
    else
      to_enum(:index_by) { size if respond_to?(:size) }
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L52" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-index_with">
            
              index_with(default = (no_default = true))
            
          </h3>

          
            <div class="description">
              <p>Convert an enumerable to a hash, using the element as the key and the block result as the value.</p>

<pre><code>post = Post.new(title: &quot;hey there&quot;, body: &quot;what&#39;s up?&quot;)

%i( title body ).index_with { |attr_name| post.public_send(attr_name) }
# =&gt; { title: &quot;hey there&quot;, body: &quot;what&#39;s up?&quot; }
</code></pre>

<p>If an argument is passed instead of a block, it will be used as the value for all elements:</p>

<pre><code>%i( created_at updated_at ).index_with(Time.now)
# =&gt; { created_at: 2020-03-09 22:31:47, updated_at: 2020-03-09 22:31:47 }
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 75
  def index_with(default = (no_default = true))
    if block_given?
      result = {}
      each { |elem| result[elem] = yield(elem) }
      result
    elsif no_default
      to_enum(:index_with) { size if respond_to?(:size) }
    else
      result = {}
      each { |elem| result[elem] = default }
      result
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L75" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-many-3F">
            
              many?()
            
          </h3>

          
            <div class="description">
              <p>Returns <code>true</code> if the enumerable has more than 1 element. Functionally equivalent to <code>enum.to_a.size &gt; 1</code>. Can be called with a block too, much like any?, so <code>people.many? { |p| p.age &gt; 26 }</code> returns <code>true</code> if more than one person is over 26.</p>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 93
  def many?
    cnt = 0
    if block_given?
      any? do |*args|
        cnt += 1 if yield(*args)
        cnt &gt; 1
      end
    else
      any? { (cnt += 1) &gt; 1 }
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L93" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-maximum">
            
              maximum(key)
            
          </h3>

          
            <div class="description">
              <p>Calculates the maximum from the extracted elements.</p>

<pre><code>payments = [Payment.new(5), Payment.new(15), Payment.new(10)]
payments.maximum(:price) # =&gt; 15
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 40
  def maximum(key)
    map(&amp;key).max
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L40" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-minimum">
            
              minimum(key)
            
          </h3>

          
            <div class="description">
              <p>Calculates the minimum from the extracted elements.</p>

<pre><code>payments = [Payment.new(5), Payment.new(15), Payment.new(10)]
payments.minimum(:price) # =&gt; 5
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 32
  def minimum(key)
    map(&amp;key).min
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L32" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-pick">
            
              pick(*keys)
            
          </h3>

          
            <div class="description">
              <p>Extract the given key from the first element in the enumerable.</p>

<pre><code>[{ name: &quot;David&quot; }, { name: &quot;Rafael&quot; }, { name: &quot;Aaron&quot; }].pick(:name)
# =&gt; &quot;David&quot;

[{ id: 1, name: &quot;David&quot; }, { id: 2, name: &quot;Rafael&quot; }].pick(:id, :name)
# =&gt; [1, &quot;David&quot;]
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 161
  def pick(*keys)
    return if none?

    if keys.many?
      keys.map { |key| first[key] }
    else
      first[keys.first]
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L161" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-pluck">
            
              pluck(*keys)
            
          </h3>

          
            <div class="description">
              <p>Extract the given key from each element in the enumerable.</p>

<pre><code>[{ name: &quot;David&quot; }, { name: &quot;Rafael&quot; }, { name: &quot;Aaron&quot; }].pluck(:name)
# =&gt; [&quot;David&quot;, &quot;Rafael&quot;, &quot;Aaron&quot;]

[{ id: 1, name: &quot;David&quot; }, { id: 2, name: &quot;Rafael&quot; }].pluck(:id, :name)
# =&gt; [[1, &quot;David&quot;], [2, &quot;Rafael&quot;]]
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 145
  def pluck(*keys)
    if keys.many?
      map { |element| keys.map { |key| element[key] } }
    else
      key = keys.first
      map { |element| element[key] }
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L145" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-sole">
            
              sole()
            
          </h3>

          
            <div class="description">
              <p>Returns the sole item in the enumerable. If there are no items, or more than one item, raises <code>Enumerable::SoleItemExpectedError</code>.</p>

<pre><code>[&quot;x&quot;].sole          # =&gt; &quot;x&quot;
Set.new.sole        # =&gt; Enumerable::SoleItemExpectedError: no item found
{ a: 1, b: 2 }.sole # =&gt; Enumerable::SoleItemExpectedError: multiple items found
</code></pre>
            </div>
          

            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/enumerable.rb, line 211
  def sole
    case count
    when 1   then return first # rubocop:disable Style/RedundantReturn
    when 0   then raise ActiveSupport::EnumerableCoreExt::SoleItemExpectedError, &quot;no item found&quot;
    when 2.. then raise ActiveSupport::EnumerableCoreExt::SoleItemExpectedError, &quot;multiple items found&quot;
    end
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/enumerable.rb#L211" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-without">
            
              without(*elements)
            
          </h3>

          
            <div class="description">
              
            </div>
          

            <div class="aka">
              Alias for: <a href="Enumerable.html#method-i-excluding">excluding</a>
            </div>
          

        </div>
        
      
</div>

    </div>
</div>