prettify XML string output by registering default namespace prefixes

Author: spaceone

src/saml2/__init__.py

@@ -42,7 +42,11 @@
 
 NAMESPACE = 'urn:oasis:names:tc:SAML:2.0:assertion'
 # TEMPLATE = '{urn:oasis:names:tc:SAML:2.0:assertion}%s'
-# XSI_NAMESPACE = 'http://www.w3.org/2001/XMLSchema-instance'
+SAMLP_NAMESPACE = 'urn:oasis:names:tc:SAML:2.0:protocol'
+XSI_NAMESPACE = 'http://www.w3.org/2001/XMLSchema-instance'
+XS_NAMESPACE = 'http://www.w3.org/2001/XMLSchema'
+DS_NAMESPACE = 'http://www.w3.org/2000/09/xmldsig#'
+DEFAULT_NS_PREFIXES = {'saml': NAMESPACE, 'samlp': SAMLP_NAMESPACE, 'ds': DS_NAMESPACE, 'xsi': XSI_NAMESPACE, 'xs': XS_NAMESPACE}
 
 NAMEID_FORMAT_EMAILADDRESS = (
     "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress")
@@ -680,7 +684,7 @@ def to_string_force_namespace(self, nspair):
 
         return ElementTree.tostring(elem, encoding="UTF-8")
 
-    def to_string(self, nspair=None):
+    def to_string(self, nspair=DEFAULT_NS_PREFIXES):
         """Converts the Saml object to a string containing XML.
 
         :param nspair: A dictionary of prefixes and uris to use when