feat(blog::api) pagination

backend/server/src/modules/blog/api/posts/pagination/mod.rs

@@ -0,0 +1,42 @@
+use crate::{
+    constants::blog::PAGE_SIZE,
+    utils::axum_response::{err_resp, succ_resp},
+};
+
+use axum::{extract::State, http::StatusCode, response::Response};
+use serde::Serialize;
+use serde_json::{Value, json};
+use sqlx::{FromRow, PgPool, Row, query_as};
+
+#[derive(FromRow, Serialize)]
+struct DBPaginationRow {
+    page_count: i32,
+    total_count: i64,
+}
+
+impl From<DBPaginationRow> for Value {
+    fn from(value: DBPaginationRow) -> Self {
+        json!({
+            "page_count": value.page_count,
+            "total_count": value.total_count
+        })
+    }
+}
+
+pub async fn handler(State(db_connection): State<PgPool>) -> Response<String> {
+    match query_as::<_, DBPaginationRow>(
+        r#"
+        SELECT 
+            cast(ceil(count(*) / cast($1 AS FLOAT)) AS INTEGER) AS page_count,
+            count(*) AS total_count
+        FROM posts;
+    "#,
+    )
+    .bind(PAGE_SIZE as i64)
+    .fetch_one(&db_connection)
+    .await
+    {
+        Ok(res) => succ_resp(StatusCode::OK, res.into()),
+        Err(e) => err_resp(StatusCode::INTERNAL_SERVER_ERROR, e.to_string()),
+    }
+}