diff --git a/Cargo.toml b/Cargo.toml
index d128a9c..46c254d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rust-rocket-sample"
-version = "0.1.1"
+version = "1.0.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
diff --git a/src/errors/response.rs b/src/errors/response.rs
index 8b741c4..f98b3ec 100644
--- a/src/errors/response.rs
+++ b/src/errors/response.rs
@@ -22,10 +22,12 @@ pub struct MyError {
 }
 
 impl MyError {
+    // building a custom error.
     pub fn build(code: u16, description: Option<String>) -> MyError {
         let reason: String;
         match code {
             400 => reason = "Bad Request".to_string(),
+            401 => reason = "Unauthorized".to_string(),
             _ => reason = "Error".to_string(),
         }
         MyError {
@@ -93,7 +95,8 @@ impl OpenApiResponderInner for MyError {
         Ok(Responses {
             responses: okapi::map! {
                 "400".to_owned() => RefOr::Object(bad_request_response(gen)),
-                "401".to_owned() => RefOr::Object(unauthorized_response(gen)),
+                // Note: 401 is already declared for ApiKey. so this is not essential.
+                // "401".to_owned() => RefOr::Object(unauthorized_response(gen)),
             },
             ..Default::default()
         })
diff --git a/src/request_guards/basic.rs b/src/request_guards/basic.rs
index 18c285b..9321ac4 100644
--- a/src/request_guards/basic.rs
+++ b/src/request_guards/basic.rs
@@ -10,7 +10,7 @@ use rocket_okapi::{
 };
 use std::env;
 
-use crate::errors::response::{bad_request_response, unauthorized_response};
+use crate::errors::response::unauthorized_response;
 
 // #[derive(OpenApiFromRequest)]
 pub struct ApiKey(String);
@@ -61,7 +61,7 @@ impl<'a> OpenApiFromRequest<'a> for ApiKey {
         // Each security requirement needs to be met before access is allowed.
         security_req.insert("ApiKey".to_owned(), Vec::new());
         Ok(RequestHeaderInput::Security(
-            "ApiKeyAuth".to_owned(),
+            "ApiKey".to_owned(),
             security_scheme,
             security_req,
         ))
@@ -71,7 +71,6 @@ impl<'a> OpenApiFromRequest<'a> for ApiKey {
         use rocket_okapi::okapi::openapi3::RefOr;
         Ok(Responses {
             responses: okapi::map! {
-                "400".to_owned() => RefOr::Object(bad_request_response(gen)),
                 "401".to_owned() => RefOr::Object(unauthorized_response(gen)),
             },
             ..Default::default()
diff --git a/src/routes/customer.rs b/src/routes/customer.rs
index 92f8fa0..99e8cf1 100644
--- a/src/routes/customer.rs
+++ b/src/routes/customer.rs
@@ -21,30 +21,30 @@ use crate::errors::response::MyError;
 #[get("/customer?<limit>&<page>")]
 pub async fn get_customers(
     db: &State<Database>,
-    limit: i64,
+    limit: Option<i64>,
     page: Option<i64>,
-) -> Result<Json<Vec<Customer>>, BadRequest<Json<MessageResponse>>> {
+) -> Result<Json<Vec<Customer>>, MyError> {
     // Error handling
-    if limit < 0 {
-        return Err(BadRequest(Some(Json(MessageResponse {
-            message: "limit cannot be less than 0".to_string(),
-        }))));
-    }
-
-    if !page.is_none() && page.unwrap() < 1 {
-        return Err(BadRequest(Some(Json(MessageResponse {
-            message: "page cannot be less than 1".to_string(),
-        }))));
-    }
-
-    match customer::find_customer(&db, limit, if page.is_none() { 1 } else { page.unwrap() }).await
-    {
+    // This is also valid when strict checking is necessary.
+    // if limit < 0 {
+    //     return Err(BadRequest(Some(Json(MessageResponse {
+    //         message: "limit cannot be less than 0".to_string(),
+    //     }))));
+    // }
+    // if !page.is_none() && page.unwrap() < 1 {
+    //     return Err(BadRequest(Some(Json(MessageResponse {
+    //         message: "page cannot be less than 1".to_string(),
+    //     }))));
+    // }
+
+    // Setting default values
+    let limit: i64 = limit.unwrap_or(12);
+    let page: i64 = page.unwrap_or(1);
+    match customer::find_customer(&db, limit, page).await {
         Ok(_customer_docs) => Ok(Json(_customer_docs)),
         Err(_error) => {
             println!("{:?}", _error);
-            Err(BadRequest(Some(Json(MessageResponse {
-                message: _error.to_string(),
-            }))))
+            return Err(MyError::build(400, Some(_error.to_string())));
         }
     }
 }
diff --git a/src/routes/mod.rs b/src/routes/mod.rs
index d6ac918..010b19d 100644
--- a/src/routes/mod.rs
+++ b/src/routes/mod.rs
@@ -6,7 +6,7 @@ use crate::models::response::MessageResponse;
 pub mod customer;
 
 /// This is a description. <br />You can do simple html <br /> like <b>this<b/>
-#[openapi(tag = "Hello")]
+#[openapi(tag = "Hello World")]
 #[get("/")]
 pub fn index() -> Json<MessageResponse> {
     Json(MessageResponse {