diff --git a/src/lib.rs b/src/lib.rs
index 7d12d9a..40cd894 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,14 +1,4 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
-}
+// SPDX-FileCopyrightText: 2023 Awayume <dev@awayume.jp>
+// SPDX-License-Identifier: Apache-2.0
 
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}
+pub use url_parser_trait::QueryParams;
diff --git a/url_parser_trait/src/lib.rs b/url_parser_trait/src/lib.rs
index 7d12d9a..7f8ade7 100644
--- a/url_parser_trait/src/lib.rs
+++ b/url_parser_trait/src/lib.rs
@@ -1,14 +1,47 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
+// SPDX-FileCopyrightText: 2023 Awayume <dev@awayume.jp>
+// SPDX-License-Identifier: Apache-2.0
+
+use std::collections::HashMap;
+
+
+pub trait QueryParams {
+    fn get_items_as_string_map(&self) -> HashMap<String, String>;
+
+    fn to_query_params(&self) -> String {
+        let items: HashMap<String, String> = self.get_items_as_string_map();
+        let mut query: String = "?".to_string();
+
+        for (key, value) in items {
+            query += &format!("{}={}&", key, value);
+        }
+
+        query.pop();
+        query
+    }
 }
 
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    struct Param {
+        user_id: u8,
+        user_name: String,
+    }
+
+    impl QueryParams for Param {
+        fn get_items_as_string_map(&self) -> HashMap<String, String> {
+            let mut map: HashMap<String, String> = HashMap::new();
+            map.insert("user_id".to_string(), self.user_id.to_string());
+            map.insert("user_name".to_string(), self.user_name.clone());
+            map
+        }
+    }
+
     #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+    fn check_query() {
+        let param: Param = Param {user_id: 1, user_name: "Awayume".to_string()};
+        assert_eq!(&param.to_query_params(), "?user_id=1&user_name=Awayume");
     }
 }