Add data attribute api to all tag types.

This introduces a new feature that enhances the api to accept a data
attribute.

```
meta(
  tag_type: {
    value: 'value',
    data: { 'data-attr-name' => 'data attr value' }
  }
)
```

Multiple data attributes can be specified:

```
meta(
  tag_type: {
    value: 'value',
    data: { 'attr-1' => 'one', 'attr-2' => 'two' }
  }
)
```

Custom tags can be registered:

```
Metamagic::Renderer.register_tag_type :custom, ->(key, value, data) do
  tag(:custom_tag, name: key, value: value, data: data)
end
```

This is backwards compatible with the existing api.

README.md

@@ -18,7 +18,7 @@ In your *Gemfile*:
 ```ruby
 gem 'metamagic'
 ```
-  
+
 Then run `bundle install`.
 
 Examples
@@ -217,7 +217,7 @@ For custom meta tags, you can use it like this:
 meta my_custom_name: "My custom value"
 %>
 ```
-  
+
 This will generate the following:
 
 ```html
@@ -404,6 +404,46 @@ custom key_one: "My first key",
 %>
 ```
 
+### Adding data attributes to tags
+
+All tag types can add data attributes.
+
+```erb
+<%
+meta title: "My Title",
+     description: {
+       value: "content",
+       data: { "attr-name" => "data attr value" }
+     }
+%>
+```
+
+This will render the following:
+
+```html
+<title>My Title</title>
+<meta name="description" content="content" data-attr-name="data attr value" />
+```
+
+Multiple data attributes can be specified:
+
+```erb
+<%
+meta title: "My Title",
+     description: {
+       value: "content",
+       data: { "attr-name-1" => "one", "attr-name-2" => "two" }
+     }
+%>
+```
+
+This will render the following:
+
+```html
+<title>My Title</title>
+<meta name="description" content="content" data-attr-1="one" data-attr-2="two" />
+```
+
 Requirements
 ------------
 

lib/metamagic.rb

@@ -1,5 +1,6 @@
 %w{
   version
+  value
   tag
   tags/meta_tag
   tags/title_tag
@@ -12,4 +13,4 @@
   view_helper
 }.each { |f| require "metamagic/#{f}" }
 
-ActionView::Base.send :include, Metamagic::ViewHelper
+ActionView::Base.send :include, Metamagic::ViewHelper

lib/metamagic/renderer.rb

@@ -113,12 +113,12 @@ def transform_hash(hash, path = "")
       hash.each_with_object({}) do |(k, v), ret|
         key = path + k.to_s
 
-        if v.is_a?(Hash)
+        if v.is_a?(Hash) && !v.key?(:value)
           ret.merge! transform_hash(v, "#{key}:")
         else
           ret[key] = v
         end
       end
     end
   end
-end
+end

lib/metamagic/tag.rb

@@ -37,7 +37,9 @@ def interpolated_values
         else
           raise "Unknown template type #{template.class}."
         end
-      end.flatten.compact.uniq.map { |value| ERB::Util.html_escape(value) }
+      end.flatten.compact.uniq.map do |value|
+        Metamagic::Value.create_escaped(value)
+      end
     end
 
     def ==(other)
@@ -53,4 +55,4 @@ def method_missing(method, *args, &block)
       context.send(method, *args, &block)
     end
   end
-end
+end

lib/metamagic/tags/custom_tag.rb

@@ -12,7 +12,20 @@ def remove_prefix?
     end
 
     def to_html
-      instance_exec key, interpolated_values, &render_proc
+      if render_proc.arity == 2
+        instance_exec(
+          key,
+          interpolated_values.map(&:value),
+          &render_proc
+        )
+      else
+        instance_exec(
+          key,
+          interpolated_values.map(&:value),
+          interpolated_values.first.data,
+          &render_proc
+        )
+      end
     end
   end
-end
+end

lib/metamagic/tags/link_tag.rb

@@ -1,7 +1,18 @@
 module Metamagic
   class LinkTag < Tag
     def to_html
-      interpolated_values.map { |value| tag(:link, rel: key, href: value) }.join("\n").html_safe.presence
+      interpolated_values.map do |value|
+        options = {
+          rel: key,
+          href: value.value,
+          data: value.data
+        }.compact
+
+        tag(:link, **options)
+      end
+        .join("\n")
+        .html_safe
+        .presence
     end
   end
-end
+end

lib/metamagic/tags/meta_tag.rb

@@ -2,7 +2,14 @@ module Metamagic
   class MetaTag < Tag
     def to_html
       return if interpolated_values.empty?
-      tag(:meta, name: key, content: interpolated_values.join(", ").html_safe)
+
+      options = {
+        name: key,
+        content: interpolated_values.map(&:value).join(", ").html_safe,
+        data: interpolated_values.first.data
+      }.compact
+
+      tag(:meta, **options)
     end
 
     def sort_order
@@ -13,4 +20,4 @@ def remove_prefix?
       false
     end
   end
-end
+end

lib/metamagic/tags/property_tag.rb

@@ -1,11 +1,22 @@
 module Metamagic
   class PropertyTag < Tag
     def to_html
-      interpolated_values.map { |value| tag(:meta, property: key, content: value) }.join("\n").html_safe.presence
+      interpolated_values.map do |value|
+        options = {
+          property: key,
+          content: value.value,
+          data: value.data
+        }.compact
+
+        tag(:meta, **options)
+      end
+        .join("\n")
+        .html_safe
+        .presence
     end
 
     def sort_order
       3
     end
   end
-end
+end

lib/metamagic/tags/title_tag.rb

@@ -1,11 +1,13 @@
 module Metamagic
   class TitleTag < Tag
     def to_html
-      content_tag(:title, interpolated_values.join(separator).html_safe) if interpolated_values.any?
+      values = interpolated_values.map(&:value).join(separator).html_safe
+
+      content_tag(:title, values) if values.length > 0
     end
 
     def sort_order
       1
     end
   end
-end
+end

lib/metamagic/value.rb

@@ -0,0 +1,46 @@
+module Metamagic
+  class Value
+    def self.create_escaped(value)
+      value.is_a?(Hash) ? ValueHash.new(value) : ValueString.new(value)
+    end
+
+    def escape(string)
+      ERB::Util.html_escape(string)
+    end
+  end
+
+  class ValueString < Value
+    attr_reader :value
+    def initialize(value)
+      @value = escape(value)
+    end
+
+    def data
+      nil
+    end
+  end
+
+  class ValueHash < Value
+    attr_reader :value_hash
+    def initialize(value_hash)
+      @value_hash = value_hash
+      @value_hash[:value] = if value.is_a?(Array)
+                              value.map { |v| escape(v) }
+                            else
+                              escape(value)
+                            end
+
+      if @value_hash.key?(:data)
+        @value_hash[:data] = data.map { |k, v| [escape(k), escape(v)] }.to_h
+      end
+    end
+
+    def value
+      value_hash[:value]
+    end
+
+    def data
+      value_hash[:data]
+    end
+  end
+end

test/custom_tag_test.rb

@@ -15,4 +15,4 @@ class CustomTagTest < ActionView::TestCase
     assert_equal %{<title>Test Title</title>\n<custom_tag one="custom:first" two="This is the first" />\n<custom_tag one="custom:second" two="This is the second" />},
                  metamagic
   end
-end
+end

test/data_attribute_test.rb

@@ -0,0 +1,112 @@
+require 'test_helper'
+
+class DataAttributeTest < ActionView::TestCase
+  include Metamagic::ViewHelper
+
+  test "title" do
+    meta title: {
+      value: "Test Title",
+      data: { "test-attr" => "title" }
+    }
+
+    assert_equal_segment %{<title data-test-attr="title">Test Title</title>},
+                 metamagic
+  end
+
+  test "title with multiple data attrs" do
+    meta title: {
+      value: "Test Title",
+      data: { "test-attr-1" => "one", "test-attr-2" => "two" }
+    }
+
+    assert_equal_segment %{<title data-test-1="one" data-test-2="two">Test Title</title>},
+                 metamagic
+  end
+
+  test "title with data attr api and no data attribute specified" do
+    meta title: { value: "Test Title" }
+
+    assert_equal_segment %{<title>Test Title</title>},
+                 metamagic
+  end
+
+  test "link rel with data attr" do
+    meta rel: {
+      author: {
+        value: "http://test.com/author.html",
+        data: { "test-attr" => "test" }
+      }
+    }
+    rel publisher: {
+      value: "http://test.com/publisher.html",
+      data: { "test-attr" => "test" }
+    }
+
+    assert_equal_segment %{<link href="http://test.com/author.html" rel="author" data-test-attr="test"/>\n<link href="http://test.com/publisher.html" rel="publisher" data-test-attr="test"/>},
+                 metamagic
+  end
+
+  test "twitter tag with data attribute" do
+    meta title: "Test Title",
+         twitter: {
+           card: {
+            value: :summary,
+            data: { "test-attr" => "test" }
+           }
+         }
+    twitter site: {
+      value: "@flickr",
+      data: { "test-attr" => "test" }
+    }
+
+    assert_equal_segment %{<title>Test Title</title>\n<meta content="summary" name="twitter:card" data-test-attr="test" />\n<meta content="@flickr" name="twitter:site" data-test-attr="test" />},
+                 metamagic
+  end
+
+  test "meta tags with data attr" do
+    meta keywords: {
+           value: %w{one two three},
+           data: { "test-attr" => "test" }
+         },
+         description: {
+           value: "My description",
+           data: { "test-attr" => "test" }
+         }
+
+    assert_equal_segment %{<meta content="one, two, three" name="keywords" data-test-attr="test" />\n<meta content="My description" name="description" data-test-attr="test" />},
+                 metamagic
+  end
+
+  test "open graph tags with data attr" do
+    meta og: {
+           image: {
+             url: {
+               value: "http://test.com/image.jpg",
+               data: { "test-attr" => "test" }
+             }
+           }
+         }
+
+    assert_equal_segment %{<meta content="http://test.com/image.jpg" property="og:image:url" data-test-attr="test" />},
+                 metamagic
+  end
+
+  test "custom tags with data attr" do
+    Metamagic::Renderer.register_tag_type :custom, ->(key, value, data) { tag(:custom_tag, one: key, two: value, data: data) }
+
+    meta title: "Test Title",
+         custom: {
+           first: {
+             value: "This is the first",
+             data: { "test-attr" => "test" }
+           },
+           second: {
+             value: "This is the second",
+             data: { "test-attr" => "test" }
+           }
+         }
+
+    assert_equal %{<title>Test Title</title>\n<custom_tag one="custom:first" two="This is the first" data-test-attr="test" />\n<custom_tag one="custom:second" two="This is the second" data-test-attr="test" />},
+                 metamagic
+  end
+end