Doc: added initial version of network tutorial.

tutorial/Network01/Network01.upp

@@ -0,0 +1,13 @@
+description "Obtaining data from the internet using HttpRequest\377";
+
+uses
+	Core,
+	Core/SSL;
+
+file
+	outpuit.json,
+	main.cpp;
+
+mainconfig
+	"" = "";
+

tutorial/Network01/main.cpp

@@ -0,0 +1,43 @@
+#include <Core/Core.h>
+
+using namespace Upp;
+
+CONSOLE_APP_MAIN {
+	HttpRequest http(
+		"https://restcountries.com/v3.1/name/germany?fullText=true&fields=name,capital");
+	auto content = http.Method(HttpRequest::METHOD_GET).Execute();
+	if(content.IsVoid()) {
+		Cout() << "Failed to execute GET request wit error code " << http.GetStatusCode()
+			   << ".\n";
+		return;
+	}
+
+	auto json = ParseJSON(content);
+	if(json.IsError()) {
+		Cout() << "Failed to parse JSON response.";
+		return;
+	}
+
+	if(json.GetCount() == 0) {
+		Cout() << "The JSON is empty. HTTP request returns empty countries list.\n";
+		return;
+	}
+	
+	// Let's parse the search results and display them on the terminal.
+	Cout() << "Found countries:\n";
+	for(const auto& result : json) {
+		String common_name;
+		String capital;
+
+		common_name = result["name"]["common"];
+		for(const auto& result_capital : result["capital"]) {
+			capital = result_capital;
+
+			// Some countries like South Africa might have more than one capital city. For this
+			// tutorial, let's ignore it and display only the first result on the list.
+			break;
+		}
+
+		Cout() << "- " << common_name << " with " << capital << " as a capital city.\n";
+	}
+}

tutorial/Network01/outpuit.json

@@ -0,0 +1,9 @@
+
+[{
+	name : {
+		common : Germany,
+		official : Federal Republic of Germany,
+		nativeName : {deu : {official : Bundesrepublik Deutschland, common : Deutschland}}
+	},
+	capital : [Berlin]
+}]