util.datamapper: Deal with locally built stanzas missing xmlns

So the problem is that xmlns is not inherited when building a stanza,
and then :get_child(n, ns) with an explicit namespace does not find that
such child tags.

E.g.
local t = st.stanza("foo", { xmlns = "urn:example:bar" })
	:text_tag("hello", "world");
assert(t:get_child("hello", "urn:example:bar"), "This fails");

Meanwhile, during parsing (util.xmppstream or util.xml) child tags do
get the parents xmlns when not overriding them.

Thus, in the above example, if the stanza is passed trough
`t = util.xml.parse(tostring(t))` then the assert succeeds.

This change makes it so that it leaves out the namespace argument to
:get_child when it is the same as the current/parent namespace, which
behaves the same for both built and parsed stanzas.

1 files changed, 5 insertions, 5 deletions

diff --git a/util/datamapper.lua b/util/datamapper.lua
index 3377413f..7aa916bc 100644
--- a/util/datamapper.lua
+++ b/util/datamapper.lua
@@ -29,7 +29,7 @@ local function unpack_propschema(propschema, propname, current_ns)
 	local proptype = "string"
 	local value_where = propname and "in_text_tag" or "in_text"
 	local name = propname
-	local namespace = current_ns
+	local namespace
 	local prefix
 	local single_attribute
 	local enums
@@ -50,7 +50,7 @@ local function unpack_propschema(propschema, propname, current_ns)
 			if xml.name then
 				name = xml.name
 			end
-			if xml.namespace then
+			if xml.namespace and xml.namespace ~= current_ns then
 				namespace = xml.namespace
 			end
 			if xml.prefix then
@@ -105,7 +105,7 @@ local function extract_value(s, value_where, proptype, name, namespace, prefix,
 		local attr = name
 		if prefix then
 			attr = prefix .. ":" .. name
-		elseif namespace ~= s.attr.xmlns then
+		elseif namespace and namespace ~= s.attr.xmlns then
 			attr = namespace .. "\1" .. name
 		end
 		return s.attr[attr]
@@ -218,7 +218,7 @@ local function unparse_property(out, v, proptype, propschema, value_where, name,
 		local attr = name
 		if prefix then
 			attr = prefix .. ":" .. name
-		elseif namespace ~= current_ns then
+		elseif namespace and namespace ~= current_ns then
 			attr = namespace .. "\1" .. name
 		end
 
@@ -229,7 +229,7 @@ local function unparse_property(out, v, proptype, propschema, value_where, name,
 		assert(single_attribute)
 		local propattr = {}
 
-		if namespace ~= current_ns then
+		if namespace and namespace ~= current_ns then
 			propattr.xmlns = namespace
 		end