diff --git a/lib/couchdb.js b/lib/couchdb.js
index 58be45d..9d632f7 100644
--- a/lib/couchdb.js
+++ b/lib/couchdb.js
@@ -720,7 +720,7 @@ CouchDB.prototype.replaceById = function(model, id, data, options, cb) {
  */
 CouchDB.prototype.selectModel = function(model, migrate) {
   var self = this;
-  var dbName, db, mo;
+  var dbName, db, mo, partitionKey;
   var modelView = null;
   var modelSelector = null;
   var dateFields = [];
@@ -747,20 +747,27 @@ CouchDB.prototype.selectModel = function(model, migrate) {
   }
 
   for (var p in mo.properties) {
-    if (mo.properties[p].type.name === 'Date') {
+    debug('visiting model property %s', p);
+    if (mo.properties[p].type && mo.properties[p].type.name === 'Date') {
       dateFields.push(p);
     }
+    if (mo.properties[p].isPartitionKey) {
+      partitionKey = p;
+      debug('partition key name %s', partitionKey);
+    }
   }
+
   var idName = this.idName(model);
   debug('CouchDB.prototype.selectModel use %j', dbName);
   this.pool[model] = {
-    mo: mo,
+    dateFields: dateFields,
     db: self.getDriverInst().use(dbName),
+    dbName: dbName,
     idName: idName,
-    modelView: modelView,
+    mo: mo,
     modelSelector: modelSelector,
-    dateFields: dateFields,
-    dbName: dbName,
+    modelView: modelView,
+    partitionKey: partitionKey,
   };
 
   // nano doesn't have api 'find' while nodejs-cloudant has