Added the method, which acts like for

  getting the value of an attribute, but which joins attribute
  multi-values into a single string value. [bug=1678589]

4 files changed, 28 insertions, 7 deletions

diff --git a/NEWS.txt b/NEWS.txt
index 0fa568c..aacd025 100644
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -1,4 +1,8 @@
-= 4.5.4 (Unreleased) =
+= 4.6.0 (Unreleased) =
+
+* Added the `Tag.stringattr` method, which acts like `Tag.get` for
+  getting the value of an attribute, but which joins attribute
+  multi-values into a single string value. [bug=1678589]
 
 * It's now possible to use a tag's namespace prefix when searching,
   e.g. soup.find('namespace:tag') [bug=1655332]
diff --git a/bs4/element.py b/bs4/element.py
index 115ab24..5462592 100644
--- a/bs4/element.py
+++ b/bs4/element.py
@@ -131,8 +131,8 @@ class PageElement(object):
     # to methods like encode() and prettify():
     #
     # "html" - All Unicode characters with corresponding HTML entities
-    #   are converted to those entities on output.
-    # "minimal" - Bare ampersands and angle brackets are converted to
+    #   are converted to those entities on output. 
+   # "minimal" - Bare ampersands and angle brackets are converted to
     #   XML entities: & < >
     # None - The null formatter. Unicode characters are never
     #   converted to entities.  This is not recommended, but it's
@@ -992,6 +992,13 @@ class Tag(PageElement):
         attribute."""
         return self.attrs.get(key, default)
 
+    def string_attr(self, key, default=None):
+        """The same as get(), but converts lists of values to strings."""
+        value = self.get(key, default)
+        if isinstance(value, list):
+            value = " ".join(value)
+        return value
+    
     def has_attr(self, key):
         return key in self.attrs
 
diff --git a/bs4/tests/test_tree.py b/bs4/tests/test_tree.py
index 354473a..f57255d 100644
--- a/bs4/tests/test_tree.py
+++ b/bs4/tests/test_tree.py
@@ -1286,6 +1286,10 @@ class TestCDAtaListAttributes(SoupTest):
         soup = self.soup("<a class='foo\tbar'>")
         self.assertEqual(b'<a class="foo bar"></a>', soup.a.encode())
 
+    def test_attribute_values_joined_into_string_through_string_attr(self):
+        soup = self.soup("<a class='foo\tbar'>")
+        self.assertEqual(b'foo bar', soup.a.string_attr('class'))
+        
     def test_accept_charset(self):
         soup = self.soup('<form accept-charset="ISO-8859-1 UTF-8">')
         self.assertEqual(['ISO-8859-1', 'UTF-8'], soup.form['accept-charset'])
diff --git a/doc/source/index.rst b/doc/source/index.rst
index 56aa7fe..0d13e0a 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -402,13 +402,13 @@ one CSS class). Others include ``rel``, ``rev``, ``accept-charset``,
 ``headers``, and ``accesskey``. Beautiful Soup presents the value(s)
 of a multi-valued attribute as a list::
 
- css_soup = BeautifulSoup('<p class="body strikeout"></p>')
- css_soup.p['class']
- # ["body", "strikeout"]
-
  css_soup = BeautifulSoup('<p class="body"></p>')
  css_soup.p['class']
  # ["body"]
+  
+ css_soup = BeautifulSoup('<p class="body strikeout"></p>')
+ css_soup.p['class']
+ # ["body", "strikeout"]
 
 If an attribute `looks` like it has more than one value, but it's not
 a multi-valued attribute as defined by any version of the HTML
@@ -428,6 +428,12 @@ consolidated::
  print(rel_soup.p)
  # <p>Back to the <a rel="index contents">homepage</a></p>
 
+You can use ```string_attr`` to get the value of any attribute as a
+string, whether or not it's a multi-valued atribute::
+
+  css_soup.p.string_attr('class')
+  # "body strikeout"
+ 
 If you parse a document as XML, there are no multi-valued attributes::
 
  xml_soup = BeautifulSoup('<p class="body strikeout"></p>', 'xml')