don't overwrite IDs

src/routes.rs

@@ -27,9 +27,10 @@ pub(crate) async fn post_create(req: Request, ctx: RouteContext<()>) -> Result<R
         return Response::error(e.to_string(), 400);
     }
 
-    let new_id = create_new_target(&ctx, &target)
-        .await
-        .expect("couldn't create target");
+    let new_id = match create_new_target(&ctx, &target).await {
+        Ok(id) => id,
+        Err(e) => return views::create_error(e),
+    };
 
     views::create_success(target, new_id)
 }

src/store.rs

@@ -27,6 +27,16 @@ pub(crate) async fn create_new_target(ctx: &RouteContext<()>, target: &Target) -
         None => gen_unused_id(&kv).await.expect("could not generate new id"),
     };
 
+    if kv
+        .get(&new_id)
+        .text()
+        .await
+        .expect("couldn't get")
+        .is_some()
+    {
+        return Err("ID Already Exists! Choose another.".into());
+    }
+
     console_log!("creating new target with id={}: {:?}", new_id, target);
     kv.put(&new_id, target.clone())
         .expect("couldn't put new target")

src/views.rs

@@ -1,4 +1,4 @@
-use worker::{Response, Result};
+use worker::{Error, Response, Result};
 
 use crate::{util::serve_html, Stats, Target};
 
@@ -32,3 +32,14 @@ pub(crate) fn create_success(target: Target, id: String) -> Result<Response> {
     let html = format!(include_str!("./public/layout.html"), body);
     serve_html(html.as_str())
 }
+
+pub(crate) fn create_error(error: Error) -> Result<Response> {
+    let body = format!(
+        "<h1>Error creating new tracked URL</h1>
+        <a href=\"/create\">Try again</a>
+        <p class=\"error\">{}</p>",
+        error.to_string()
+    );
+    let html = format!(include_str!("./public/layout.html"), body);
+    serve_html(html.as_str())
+}