From 68082eecf9e7529bf2bea124c402d2d781288a4a Mon Sep 17 00:00:00 2001
From: mike12345567 <me@michaeldrury.co.uk>
Date: Tue, 13 Jun 2023 18:21:22 +0100
Subject: [PATCH] Fix for circular issue with primary display fields on SQL
 tables introduced in most recent update - if somehow the primary display
 field is set to a relationship field there was a chance of cyclic structure
 occurring which Koa could not convert to JSON.

---
 .../api/controllers/row/ExternalRequest.ts    |  6 +++++-
 packages/server/src/integrations/utils.ts     | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/packages/server/src/api/controllers/row/ExternalRequest.ts b/packages/server/src/api/controllers/row/ExternalRequest.ts
index b13ec22cfd..f6b75aca05 100644
--- a/packages/server/src/api/controllers/row/ExternalRequest.ts
+++ b/packages/server/src/api/controllers/row/ExternalRequest.ts
@@ -19,6 +19,7 @@ import {
   breakRowIdField,
   convertRowId,
   generateRowIdField,
+  getPrimaryDisplay,
   isRowId,
   isSQL,
 } from "../../../integrations/utils"
@@ -391,7 +392,10 @@ export class ExternalRequest {
           }
         }
         relatedRow = processFormulas(linkedTable, relatedRow)
-        const relatedDisplay = display ? relatedRow[display] : undefined
+        let relatedDisplay
+        if (display) {
+          relatedDisplay = getPrimaryDisplay(relatedRow[display])
+        }
         row[relationship.column][key] = {
           primaryDisplay: relatedDisplay || "Invalid display column",
           _id: relatedRow._id,
diff --git a/packages/server/src/integrations/utils.ts b/packages/server/src/integrations/utils.ts
index de8b318bb1..5ff9f07b89 100644
--- a/packages/server/src/integrations/utils.ts
+++ b/packages/server/src/integrations/utils.ts
@@ -328,3 +328,22 @@ export function finaliseExternalTables(
     .reduce((r, [k, v]) => ({ ...r, [k]: v }), {})
   return { tables: finalTables, errors }
 }
+
+/**
+ * Checks if the provided input is an object, but specifically not a date type object.
+ * Used during coercion of types and relationship handling, dates are considered valid
+ * and can be used as a display field, but objects and arrays cannot.
+ * @param test
+ */
+export function getPrimaryDisplay(test: any): string | undefined {
+  if (test instanceof Date) {
+    return test.toISOString()
+  }
+  if (Array.isArray(test) && test[0] && typeof test[0] !== "object") {
+    return test.join(", ")
+  }
+  if (typeof test === "object") {
+    return undefined
+  }
+  return test as string
+}