added write() method to Properties to write back persistent changes

2 files changed, 59 insertions, 5 deletions

diff --git a/doc/server/plugins/connectors/properties.txt b/doc/server/plugins/connectors/properties.txt
index 3329f48bd..7695e902c 100644
--- a/doc/server/plugins/connectors/properties.txt
+++ b/doc/server/plugins/connectors/properties.txt
@@ -53,8 +53,23 @@ more details on how Group and Client tags are parsed.)  For instance::
                    if el.tag == "Server"]
     %}
 
+If you need to make persistent changes to properties data, you can use
+the ``write`` method of the ``PropertyFile`` class::
+
+    {% python
+    import lxml.etree
+    from genshi.template import TemplateError
+    lxml.etree.SubElement(metadata.Properties['foo.xml'],
+                          "Client",
+                          name=metadata.hostname)
+    if not metadata.Properties['foo.xml'].write():
+        raise TemplateError("Failed to write changes back to foo.xml")
+
+The ``write`` method checks the data in the object against its schema
+before writing it; see `Data Structures`_ for details.
+
 As we formulate more common use cases, we will add them to the
-!PropertyFile class as methods. This will simplify templates.
+``PropertyFile`` class as methods. This will simplify templates.
 
 You can also access the XML data that comprises a property file
 directly in one of several ways:
diff --git a/src/lib/Server/Plugins/Properties.py b/src/lib/Server/Plugins/Properties.py
index 54c5def57..58f7215c9 100644
--- a/src/lib/Server/Plugins/Properties.py
+++ b/src/lib/Server/Plugins/Properties.py
@@ -1,12 +1,51 @@
+import os
+import sys
 import copy
+import logging
 import lxml.etree
-
 import Bcfg2.Server.Plugin
 
+logger = logging.getLogger('Bcfg2.Plugins.Properties')
 
 class PropertyFile(Bcfg2.Server.Plugin.StructFile):
     """Class for properties files."""
-    pass
+    def write(self):
+        """ Write the data in this data structure back to the property
+        file """
+        if self.validate_data():
+            try:
+                open(self.name,
+                     "wb").write(lxml.etree.tostring(self.xdata,
+                                                     pretty_print=True))
+                return True
+            except IOError:
+                err = sys.exc_info()[1]
+                logger.error("Failed to write %s: %s" % (self.name, err))
+                return False
+        else:
+            return False
+
+    def validate_data(self):
+        """ ensure that the data in this object validates against the
+        XML schema for this property file (if a schema exists) """
+        schemafile = self.name.replace(".xml", ".xsd")
+        if os.path.exists(schemafile):
+            try:
+                schema = lxml.etree.XMLSchema(file=schemafile)
+            except:
+                logger.error("Failed to process schema for %s" % self.name)
+                return False
+        else:
+            # no schema exists
+            return True
+
+        if not schema.validate(self.xdata):
+            logger.error("Data for %s fails to validate; run bcfg2-lint for "
+                         "more details" % self.name)
+            return False
+        else:
+            return True
+
 
 class PropDirectoryBacked(Bcfg2.Server.Plugin.DirectoryBacked):
     __child__ = PropertyFile
@@ -28,8 +67,8 @@ class Properties(Bcfg2.Server.Plugin.Plugin,
             self.store = PropDirectoryBacked(self.data, core.fam)
         except OSError:
             e = sys.exc_info()[1]
-            Bcfg2.Server.Plugin.logger.error("Error while creating Properties "
-                                             "store: %s %s" % (e.strerror, e.filename))
+            self.logger.error("Error while creating Properties store: %s %s" %
+                              (e.strerror, e.filename))
             raise Bcfg2.Server.Plugin.PluginInitError
 
     def get_additional_data(self, _):