fix(control): stop duplicating explicit id in DESCRIBE

DESCRIBE on a strict collection created with an explicit
id ... PRIMARY KEY listed the id field twice — once from the
unconditional synthetic id row and once from the declared field list
— with contradictory nullability. The synthetic id row is now emitted
only when the collection doesn't already declare one, and each
declared field's nullability is derived from its PRIMARY KEY / NOT
NULL type modifiers instead of being hardcoded nullable.

Fixes #173.

Author: farhan-syah

nodedb/src/control/server/shared/ddl/neutral/collection/describe.rs

@@ -72,14 +72,28 @@ pub fn describe_collection(
 
     let mut rows = Vec::new();
 
-    // Always has an 'id' field.
-    push_describe_row(&mut rows, "id", "TEXT", "false");
-
+    // Synthesize the implicit 'id' field only when the collection does not
+    // already declare one — a strict collection created with an explicit
+    // `id ... PRIMARY KEY` stores `id` in `coll.fields`, so emitting the
+    // synthetic row too would list `id` twice with contradictory nullability.
+    let declares_id = coll
+        .fields
+        .iter()
+        .any(|(name, _)| name.eq_ignore_ascii_case("id"));
+    if !declares_id {
+        push_describe_row(&mut rows, "id", "TEXT", "false");
+    }
     if coll.fields.is_empty() {
         push_describe_row(&mut rows, "document", "JSON", "true");
     } else {
         for (field_name, field_type) in &coll.fields {
-            push_describe_row(&mut rows, field_name, field_type, "true");
+            let upper = field_type.to_uppercase();
+            let nullable = if upper.contains("PRIMARY KEY") || upper.contains("NOT NULL") {
+                "false"
+            } else {
+                "true"
+            };
+            push_describe_row(&mut rows, field_name, field_type, nullable);
         }
     }
 

nodedb/tests/database_scoped_ddl_introspection.rs

@@ -84,6 +84,52 @@ async fn describe_collection_finds_it_in_non_default_database() {
     );
 }
 
+/// Regression for issue #173: `DESCRIBE` on a strict collection created with an
+/// explicit `id ... PRIMARY KEY` listed the `id` field twice — once from the
+/// unconditional synthetic `id` row and once from iterating the declared
+/// `coll.fields` — with contradictory nullability. The synthetic row is now
+/// emitted only when the collection does not already declare an `id`, and each
+/// declared field's nullability is derived from its type modifiers.
+#[tokio::test]
+async fn describe_strict_does_not_duplicate_explicit_id() {
+    let server = TestServer::start().await;
+
+    query_ok(
+        &server,
+        "CREATE COLLECTION desc_repro (id TEXT PRIMARY KEY, label TEXT) \
+         WITH (engine='document_strict')",
+    )
+    .await;
+
+    let describe_rows = server
+        .client
+        .simple_query("DESCRIBE desc_repro")
+        .await
+        .unwrap_or_else(|e| panic!("DESCRIBE desc_repro must succeed: {e}"));
+
+    let id_rows: Vec<&tokio_postgres::SimpleQueryRow> = describe_rows
+        .iter()
+        .filter_map(|m| match m {
+            tokio_postgres::SimpleQueryMessage::Row(row) if row.get("field") == Some("id") => {
+                Some(row)
+            }
+            _ => None,
+        })
+        .collect();
+
+    assert_eq!(
+        id_rows.len(),
+        1,
+        "DESCRIBE must list the explicit `id` PK field exactly once (pre-fix: twice), \
+         got: {describe_rows:?}"
+    );
+    assert_eq!(
+        id_rows[0].get("nullable"),
+        Some("false"),
+        "the `id` PRIMARY KEY field must be non-nullable, got: {describe_rows:?}"
+    );
+}
+
 /// `SHOW COLLECTIONS` in a non-default database must list collections
 /// created in that database.
 ///