making add() and get() more useful

diff --git a/sfa/rspecs/elements/element.py b/sfa/rspecs/elements/element.py
index 2b27d9e..f388995 100644 (file)
--- a/sfa/rspecs/elements/element.py
+++ b/sfa/rspecs/elements/element.py
@@ -2,22 +2,54 @@ class Element(dict):
 
     fields = {}
 
-    def __init__(self, fields={}, element=None):
+    def __init__(self, fields={}, element=None, keys=None):
         self.element = element
-        dict.__init__(self, self.fields) 
-        self.update(fields)
+        dict.__init__(self, self.fields)
+        if not keys:
+            keys = fields.keys()
+        for key in keys:
+            if key in fields:
+                self[key] = fields[keys] 
 
     @staticmethod
-    def get(element_class, xml, xpath, namespaces=None):
+    def get(xml, xpath, element_class=Element, fields=None):
+        """
+        Search the specifed xml node for elements that match the 
+        specified xpath query. 
+        Returns a list of objectes instanced by the specfied element_class.
+        """
+        if not fields:
+           fields = element_class.fields.keys()
         elems = xml.xpath(xpath, namespaces)
+        objs = []
+        for elem in elems:
+            if not fields:
+                obj = element_class(elem.attrib, elem)
+            else:
+                obj = element_class({}, elem)
+                for field in fields:
+                    if field in elem.attrib:
+                        obj[field] = elem.attrib[field]    
+            objs.append(obj)
         generic_elems = [element_class(elem.attrib, elem) for elem in elems]
-        return generic_elems
+        return objs
 
 
     @staticmethod
-    def add(xml, element_class, name, obj):
-        elem = xml.add_element(name)
-        for field in element_class.fields:
-            if field in obj and obj[field]:
-                elem.set(field, obj[field])
-        return elem
+    def add(xml, name, objs, fields=None):
+        """
+        Adds a child node to the specified xml node based on
+        the specified name , element class and object.    
+        """
+        if not isinstance(objs, list):
+            objs = [objs]
+        if not fields:
+            fields = obj.keys()
+        elems = []
+        for obj in objs:
+            elem = xml.add_element(name)
+            for field in fields
+                if field in obj and obj[field]:
+                    elem.set(field, obj[field])
+            elems.append(elem)
+        return elems