diff --git a/python/web/library/models.py b/python/web/library/models.py
index c2c5c5f..329cf00 100644
--- a/python/web/library/models.py
+++ b/python/web/library/models.py
@@ -12,6 +12,24 @@ class Category(models.Model):
 	id = models.CharField(max_length=255, primary_key=True)
 	name = models.CharField(max_length=255)
 
+	def to_string(self):
+		str = 'category %s\nName: %s\n' % (self.id, self.name)
+		str += 'Placement: %s\n' % self.placements_str()
+		str += 'Books:\n'
+		for book in self.books.all():
+			str += ' %-13s %-10s %s\n' % (book.isbn, book.getid() or '', book.title)
+		if len(self.books.all()) == 0:
+			str += ' (no books in this category)\n'
+		return str
+
+	def to_dict(self):
+		return { 'action': 'edit-category',
+			 'id': self.id, 'name': self.name,
+			 'placement': self.placements_str() }
+
+	def placements_str(self):
+		return ', '.join(map(lambda pl: pl.shelf, self.placement.all()))
+
 	def __unicode__(self):
 		return self.name
 
@@ -33,7 +51,7 @@ class Book(models.Model):
 #	id = models.CharField(max_length=255)
 	title = models.CharField(max_length=511)
 	subtitle = models.CharField(max_length=511, null=True, blank=True)
-	category = models.ForeignKey(Category, null=True, blank=True)
+	category = models.ForeignKey(Category, null=True, blank=True, related_name='books')
 	publisher = models.CharField(max_length=255, null=True, blank=True)
 	published_year = models.IntegerField(null=True, blank=True)
 	edition = models.IntegerField(null=True, blank=True)
diff --git a/python/worblehat.py b/python/worblehat.py
index bc0c6ee..ec30796 100755
--- a/python/worblehat.py
+++ b/python/worblehat.py
@@ -18,8 +18,8 @@ import tempfile
 
 file_encoding = 'utf8'
 
-def show_book_or_person(ids, commit_format=False, tmp_file=False):
-    objects = map(get_book_or_person, ids)
+def show(ids, commit_format=False, tmp_file=False):
+    objects = map(get_object_by_id, ids)
     for i in range(len(ids)):
         if not objects[i]:
             objects[i] = 'No book or person with id %s.\n' % ids[i]
@@ -38,16 +38,20 @@ def show_book_or_person(ids, commit_format=False, tmp_file=False):
     else:
         print output.strip()
 
-def get_book_or_person(id):
+def get_object_by_id(id):
     books = Book.objects.filter(Q(isbn=id)|Q(id__id=id)).all()
     persons = Person.objects.filter(id=id)
-    if len(books) + len(persons) > 1:
+    categories = Category.objects.filter(id=id)
+    if len(books) + len(persons) + len(categories) > 1:
         print 'Warning: More than one match for id %d.' % id
         print 'This should not happen.'
     if len(books) > 0:
         return books[0]
     if len(persons) > 0:
         return persons[0]
+    if len(categories) > 0:
+        return categories[0]
+    return None
 
 def remove_duplicates(list):
 	d = {}
@@ -198,7 +202,7 @@ def perform_action(a, new_persons):
         return p
 
 def edit_book_or_person(ids):
-    filename = show_book_or_person(ids, commit_format=True, tmp_file=True)
+    filename = show(ids, commit_format=True, tmp_file=True)
     print filename
     run_editor(filename)
     commit(filename)
@@ -206,7 +210,7 @@ def edit_book_or_person(ids):
 commands = { 'show':
              { 'args': [('ids', (1,None))],
                'options': ['commit_format', 'tmp_file'],
-               'fun': show_book_or_person },
+               'fun': show },
              'list':
                  { 'args': [('what', (1,1))],
                    'options': [],