Add possibility for adding default data nodes

New method DNode.add_default() allows add all missing default nodes.

Author: Pepa Hajek

cffi/cdefs.h

@@ -992,5 +992,16 @@ struct lysc_when** lysc_node_when(const struct lysc_node *);
 
 LY_ERR lyd_eval_xpath(const struct lyd_node *, const char *, ly_bool *);
 
+typedef LY_ERR(* lyd_merge_cb)(struct lyd_node *, const struct lyd_node *, void *);
+LY_ERR lyd_merge_module(struct lyd_node **, const struct lyd_node *, const struct lys_module *, lyd_merge_cb, void *, uint16_t);
+
+#define LYD_IMPLICIT_NO_STATE ...
+#define LYD_IMPLICIT_NO_CONFIG ...
+#define LYD_IMPLICIT_OUTPUT ...
+#define LYD_IMPLICIT_NO_DEFAULTS ...
+
+LY_ERR lyd_new_implicit_all(struct lyd_node **, const struct ly_ctx *, uint32_t, struct lyd_node **);
+
+
 /* from libc, needed to free allocated strings */
 void free(void *);

libyang/data.py

@@ -24,6 +24,25 @@
 LOG = logging.getLogger(__name__)
 
 
+# -------------------------------------------------------------------------------------
+def implicit_flags(
+    no_config: bool = False,
+    no_defaults: bool = False,
+    no_state: bool = False,
+    output: bool = False,
+) -> int:
+    flags = 0
+    if no_config:
+        flags |= lib.LYD_IMPLICIT_NO_CONFIG
+    if no_state:
+        flags |= lib.LYD_IMPLICIT_NO_STATE
+    if no_defaults:
+        flags |= lib.LYD_IMPLICIT_NO_DEFAULTS
+    if output:
+        flags |= lib.LYD_IMPLICIT_OUTPUT
+    return flags
+
+
 # -------------------------------------------------------------------------------------
 def printer_flags(
     with_siblings: bool = False,
@@ -237,6 +256,25 @@ def meta_free(self, name):
                 lib.lyd_free_meta_single(item)
                 break
 
+    def add_defaults(
+        self,
+        no_config: bool = False,
+        no_defaults: bool = False,
+        no_state: bool = False,
+        output: bool = False,
+    ):
+        flags = implicit_flags(
+            no_config=no_config,
+            no_defaults=no_defaults,
+            no_state=no_state,
+            output=output,
+        )
+        node_p = ffi.new("struct lyd_node **")
+        node_p[0] = self.cdata
+        ret = lib.lyd_new_implicit_all(node_p, self.context.cdata, flags, ffi.NULL)
+        if ret != lib.LY_SUCCESS:
+            raise self.context.error("cannot get module")
+
     def flags(self):
         ret = {"default": False, "when_true": False, "new": False}
         if self.cdata.flags & lib.LYD_DEFAULT:

tests/test_data.py

@@ -13,6 +13,7 @@
     DAnyxml,
     DataType,
     DContainer,
+    DLeaf,
     DNode,
     DNotif,
     DRpc,
@@ -210,7 +211,7 @@ def test_data_parse_config_xml(self):
         dnode = self.ctx.parse_data_mem(self.XML_CONFIG, "xml", validate_present=True)
         self.assertIsInstance(dnode, DContainer)
         try:
-            xml = dnode.print_mem("xml", with_siblings=True)
+            xml = dnode.print_mem("xml", with_siblings=True, trim_default_values=True)
             self.assertEqual(xml, self.XML_CONFIG)
         finally:
             dnode.free()
@@ -532,7 +533,7 @@ def test_data_from_dict_leaf(self):
             {"hostname": "foo"}, strict=True, validate=True, validate_present=True
         )
         try:
-            j = dnode.print_mem("json", pretty=False)
+            j = dnode.print_mem("json", pretty=False, trim_default_values=True)
         finally:
             dnode.free()
         self.assertEqual(j, '{"yolo-system:state":{"hostname":"foo"}}')
@@ -779,3 +780,15 @@ def test_find_all(self):
             self.assertEqual(urls[0].print_dict(absolute=False), expected_url)
         finally:
             dnode.free()
+
+    def test_add_defaults(self):
+        dnode = self.ctx.parse_data_mem(self.JSON_CONFIG, "json", validate_present=True)
+        node = dnode.find_path("/yolo-system:conf/speed")
+        self.assertIsInstance(node, DLeaf)
+        node.free(with_siblings=False)
+        node = dnode.find_path("/yolo-system:conf/speed")
+        self.assertIsNone(node)
+        dnode.add_defaults()
+        node = dnode.find_path("/yolo-system:conf/speed")
+        self.assertIsInstance(node, DLeaf)
+        self.assertEqual(node.value(), 4321)

tests/test_diff.py

@@ -8,6 +8,7 @@
     BaseTypeAdded,
     BaseTypeRemoved,
     Context,
+    DefaultAdded,
     EnumRemoved,
     EnumStatusAdded,
     EnumStatusRemoved,
@@ -34,6 +35,8 @@ class DiffTest(unittest.TestCase):
             (BaseTypeAdded, "/yolo-system:state/speed"),
             (BaseTypeRemoved, "/yolo-system:conf/speed"),
             (BaseTypeRemoved, "/yolo-system:state/speed"),
+            (DefaultAdded, "/yolo-system:conf/speed"),
+            (DefaultAdded, "/yolo-system:state/speed"),
             (NodeTypeAdded, "/yolo-system:conf/number"),
             (NodeTypeAdded, "/yolo-system:state/number"),
             (NodeTypeRemoved, "/yolo-system:conf/number"),

tests/yang/yolo/yolo-system.yang

@@ -104,6 +104,7 @@ module yolo-system {
         "The speed.";
       if-feature turbo-boost;
       type uint32;
+      default 4321;
     }
 
     leaf offline {