CachedLDAPConnection: Don't cache fields we don't use

I had previously said:
> It would be nice to automatically detect and drop any non text
> fields, but that's probably not worth the trouble either...

Since the configuration ID is in the cached key, we already know
exactly which fields we need to save in the cache.  Only caching those
fields avoids binary fields and fields with large values (jpegPhoto is
both).  I made the cached fields configurable because the
CachedLDAPConnection instance doesn't know about the fields needed by
format_entry() and format_columns().  If you don't configure the
cached fields, a minimal default is setup in the main block.

diff --git a/mutt-ldap.py b/mutt-ldap.py
index 7554b947a2c06921ca06de2fff62c205e35cc2f4..c2ec3b806a41f011255e3f1accafd56b5a6f219a 100755 (executable)
--- a/mutt-ldap.py
+++ b/mutt-ldap.py
@@ -65,6 +65,7 @@ CONFIG.set('results', 'optional_column', '') # mutt can display one optional col
 CONFIG.add_section('cache')
 CONFIG.set('cache', 'enable', 'yes') # enable caching by default
 CONFIG.set('cache', 'path', '~/.mutt-ldap.cache') # cache results here
+CONFIG.set('cache', 'fields', '')  # fields to cache (if empty, setup in the main block)
 #CONFIG.set('cache', 'longevity_days', '14') # TODO: cache results for 14 days by default
 CONFIG.add_section('system')
 # HACK: Python 2.x support, see http://bugs.python.org/issue2128
@@ -168,8 +169,13 @@ class CachedLDAPConnection (LDAPConnection):
                 yield entry
         else:
             entries = []
+            keys = self.config.get('cache', 'fields').split()
             for entry in super(CachedLDAPConnection, self).search(query=query):
-                entries.append(entry)
+                cn,data = entry
+                # use dict comprehensions in Python >= 2.7, see PEP 274
+                cached_data = dict(
+                    [(key, data[key]) for key in keys if key in data])
+                entries.append((cn, cached_data))
                 yield entry
             self._cache_store(query=query, entries=entries)
 
@@ -236,6 +242,13 @@ if __name__ == '__main__':
 
     if CONFIG.getboolean('cache', 'enable'):
         connection_class = CachedLDAPConnection
+        if not CONFIG.get('cache', 'fields'):
+            # setup a reasonable default
+            fields = ['mail', 'cn', 'displayName']  # used by format_entry()
+            optional_column = CONFIG.get('results', 'optional_column')
+            if optional_column:
+                fields.append(optional_column)
+            CONFIG.set('cache', 'fields', ' '.join(fields))
     else:
         connection_class = LDAPConnection