require all strings to be set

src/data.cpp

@@ -50,4 +50,19 @@ json data::process(const json &input) {
   return input;
 }
 
-bool data::validate(const json &input) {}
+bool data::validate(const json &input) {
+  const std::string name = input.value("name", "");
+  const std::string address = input.value("address", "");
+  const std::string phone = input.value("phone", "");
+  const std::string email = input.value("email", "");
+
+  const std::vector<std::string> strings{name, address, phone, email};
+
+  for (const auto &f : strings) {
+    if (f.size() == 0) {
+      return false;
+    }
+  }
+
+  return true;
+}