Avoid

Module plone.batching.batch, line 232, in previous_pages
ValueError: XXX is not in list
that can happen if b_start is too high and using orphan
See plone/Products.CMFPlone#639

CHANGES.rst

@@ -4,7 +4,9 @@ Changelog
 1.0.5 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- Make sure pagenumber value is not bigger that numpages
+  or it fails in previous_pages when using orphan
+  [gbastien]
 
 
 1.0.4 (2015-04-28)

plone/batching/batch.py

@@ -56,19 +56,22 @@ def initialize(self, start, end, size):
         self.end = end
 
         self.first = max(start - 1, 0)
-        if self.beyond:
-            self.first = self.end
-        self.length = self.end - self.first
-
         self.last = self.sequence_length - size
 
         # Set up the total number of pages
         self.numpages = calculate_pagenumber(
             self.sequence_length - self.orphan, self.pagesize, self.overlap)
 
-        # Set up the current page number
-        self._pagenumber = calculate_pagenumber(
-            self.start, self.pagesize, self.overlap)
+        if self.beyond:
+            self.first = self.end
+            # Make sure current page number is not > numpages
+            self._pagenumber = self.numpages
+        else:
+            # Set up the current page number
+            self._pagenumber = calculate_pagenumber(
+                self.start, self.pagesize, self.overlap)
+
+        self.length = self.end - self.first
 
     @property
     def navlist(self):

plone/batching/tests.py

@@ -156,6 +156,17 @@ def test_multiple_pages_longer(self):
         batch = BaseBatch(range(12), 10)
         self.assertEquals(batch.multiple_pages, True)
 
+    def test_pagenumber_never_over_numpages(self):
+        """computed _pagenumber is never > numpages, this
+           makes previous_pages not fail."""
+        batch = BaseBatch([1, 2, 3, 4, 5, 6, 7], 3, 8)
+        self.assertEquals(batch.previous_pages, [1, 2])
+        self.assertEquals(batch._pagenumber, 3)
+        # works especially with orphan
+        batch = BaseBatch([1, 2, 3, 4, 5, 6, 7], 3, 8, orphan=2)
+        self.assertEquals(batch.previous_pages, [1])
+        self.assertEquals(batch._pagenumber, 2)
+
 
 class TestQuantumBatch(unittest.TestCase):