Changeset

--- a/spec/util_stanza_spec.lua	Sat Sep 11 13:59:35 2021 +0100
+++ b/spec/util_stanza_spec.lua	Sun Sep 12 10:31:02 2021 +0100
@@ -455,6 +455,26 @@
 		end);
 	end);
 
+	describe("get_child_with_attr", function ()
+		local s = st.message({ type = "chat" })
+			:text_tag("body", "Hello world", { ["xml:lang"] = "en" })
+			:text_tag("body", "Bonjour le monde", { ["xml:lang"] = "fr" })
+			:text_tag("body", "Hallo Welt", { ["xml:lang"] = "de" })
+
+		it("works", function ()
+			assert.equal(s:get_child_with_attr("body", nil, "xml:lang", "en"):get_text(), "Hello world");
+			assert.equal(s:get_child_with_attr("body", nil, "xml:lang", "de"):get_text(), "Hallo Welt");
+			assert.equal(s:get_child_with_attr("body", nil, "xml:lang", "fr"):get_text(), "Bonjour le monde");
+			assert.is_nil(s:get_child_with_attr("body", nil, "xml:lang", "FR"));
+			assert.is_nil(s:get_child_with_attr("body", nil, "xml:lang", "es"));
+		end);
+
+		it("supports normalization", function ()
+			assert.equal(s:get_child_with_attr("body", nil, "xml:lang", "EN", string.upper):get_text(), "Hello world");
+			assert.is_nil(s:get_child_with_attr("body", nil, "xml:lang", "ES", string.upper));
+		end);
+	end);
+
 	describe("#clone", function ()
 		it("works", function ()
 			local s = st.message({type="chat"}, "Hello"):reset();

--- a/util/stanza.lua	Sat Sep 11 13:59:35 2021 +0100
+++ b/util/stanza.lua	Sun Sep 12 10:31:02 2021 +0100
@@ -191,6 +191,14 @@
 	end
 end
 
+function stanza_mt:get_child_with_attr(name, xmlns, attr_name, attr_value, normalize)
+	for tag in self:childtags(name, xmlns) do
+		if (normalize and normalize(tag.attr[attr_name]) or tag.attr[attr_name]) == attr_value then
+			return tag;
+		end
+	end
+end
+
 function stanza_mt:children()
 	local i = 0;
 	return function (a)