Merge pull request #10895 from Budibase/fix/budi-7099

MySQL cyclic JSON conversion issue with primary display columns

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,

packages/server/src/integrations/utils.ts

@@ -328,3 +328,27 @@ 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 testValue an unknown type which this function will attempt to extract
+ * a valid primary display string from.
+ */
+export function getPrimaryDisplay(testValue: unknown): string | undefined {
+  if (testValue instanceof Date) {
+    return testValue.toISOString()
+  }
+  if (
+    Array.isArray(testValue) &&
+    testValue[0] &&
+    typeof testValue[0] !== "object"
+  ) {
+    return testValue.join(", ")
+  }
+  if (typeof testValue === "object") {
+    return undefined
+  }
+  return testValue as string
+}