diff --git a/src/main.rs b/src/main.rs
index c1f06b1..e6eb372 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,12 +5,14 @@ use bayespam::classifier::Classifier;
 use serde::{Serialize, Deserialize};
 use std::path::Path;
 use std::fs::File;
+use std::io::{BufReader, BufWriter};
 
 #[derive(Debug, Hash, PartialEq, Eq)]
 #[derive(Serialize, Deserialize)]
 struct RepoId(i64);
 
 #[derive(Debug)]
+#[derive(Serialize, Deserialize)]
 struct RepoData {
     name: String,
     description: Option<String>,
@@ -21,6 +23,7 @@ struct RepoData {
 struct IssueId(i64);
 
 #[derive(Debug)]
+#[derive(Serialize, Deserialize)]
 struct IssueData {
     title: String,
     body: String,
@@ -31,6 +34,7 @@ struct IssueData {
 struct UserId(i64);
 
 #[derive(Debug)]
+#[derive(Serialize, Deserialize)]
 struct UserData {
 //    login: String,
     email: String,
@@ -284,8 +288,7 @@ async fn main() -> anyhow::Result<()> {
     let db_path = Path::new("classification.json");
     let mut db = if db_path.is_file() {
         let file = File::open(db_path)?;
-        let reader = std::io::BufReader::new(file);
-        serde_json::from_reader(reader)?
+        serde_json::from_reader(BufReader::new(file))?
     } else {
         Db::new()
     };
@@ -297,7 +300,17 @@ async fn main() -> anyhow::Result<()> {
         Auth::Token(&api_token),
         url::Url::parse("https://git.deuxfleurs.fr")?
     )?;
-    let data = get_users_data(&forge).await?;
+
+    let data_path = Path::new("data.json");
+    let data = if data_path.is_file() {
+        let file = File::open(data_path)?;
+        serde_json::from_reader(BufReader::new(file))?
+    } else {
+        let data = get_users_data(&forge).await?;
+        let file = File::create(data_path)?;
+        serde_json::to_writer(BufWriter::new(file), &db)?;
+        data
+    };
     println!("got {} users", data.len());
 
     for (user_id, user) in data {
@@ -336,8 +349,7 @@ async fn main() -> anyhow::Result<()> {
             classifier.save(&mut File::create(model_path)?, false)?;
 
             let file = File::create(db_path)?;
-            let writer = std::io::BufWriter::new(file);
-            serde_json::to_writer(writer, &db)?;
+            serde_json::to_writer(BufWriter::new(file), &db)?;
         }
     }