From 791c0635d50fc0be283f311e1663565146c018b2 Mon Sep 17 00:00:00 2001
From: Ruben Fiszel <ruben@rubenfiszel.com>
Date: Thu, 10 Nov 2022 08:48:06 +0100
Subject: [PATCH] tweak identity to extract previous_result

---
 backend/tests/worker.rs               | 36 +++++++++++++++++++++++++++
 backend/windmill-worker/src/worker.rs |  9 ++++++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/backend/tests/worker.rs b/backend/tests/worker.rs
index 981dd99d88..d236798270 100644
--- a/backend/tests/worker.rs
+++ b/backend/tests/worker.rs
@@ -1070,6 +1070,42 @@ async fn test_deno_flow(db: Pool<Postgres>) {
     }
 }
 
+#[sqlx::test(fixtures("base"))]
+async fn test_identity(db: Pool<Postgres>) {
+    initialize_tracing().await;
+
+    let server = ApiServer::start(db.clone()).await;
+
+    let flow: FlowValue = serde_json::from_value(serde_json::json!({
+        "modules": [{
+                "value": {
+                    "type": "rawscript",
+                    "language": "python3",
+                    "content": "def main(): return 42",
+                }}, {
+                    "value": {
+                        "type": "identity",
+                    },
+                }, {
+                    "value": {
+                        "type": "identity",
+                    },
+                }, {
+                    "value": {
+                        "type": "identity",
+                    },
+                }],
+    }))
+    .unwrap();
+
+    let result = RunJob::from(JobPayload::RawFlow { value: flow.clone(), path: None })
+        .run_until_complete(&db, server.addr.port())
+        .await
+        .result
+        .unwrap();
+    assert_eq!(result, serde_json::json!(42));
+}
+
 #[sqlx::test(fixtures("base"))]
 async fn test_deno_flow_same_worker(db: Pool<Postgres>) {
     initialize_tracing().await;
diff --git a/backend/windmill-worker/src/worker.rs b/backend/windmill-worker/src/worker.rs
index 468dd24d4f..d57059cc44 100644
--- a/backend/windmill-worker/src/worker.rs
+++ b/backend/windmill-worker/src/worker.rs
@@ -621,7 +621,14 @@ async fn handle_queued_job(
                 JobKind::Dependencies => {
                     handle_dependency_job(&job, &mut logs, job_dir, db, timeout, &envs).await
                 }
-                JobKind::Identity => Ok(job.args.clone().unwrap_or_else(|| Value::Null)),
+                JobKind::Identity => match job.args.clone() {
+                    Some(Value::Object(args))
+                        if args.len() == 1 && args.contains_key("previous_result") =>
+                    {
+                        Ok(args.get("previous_result").unwrap().clone())
+                    }
+                    args @ _ => Ok(args.unwrap_or_else(|| Value::Null)),
+                },
                 _ => {
                     handle_code_execution_job(
                         &job,