fix null value

apps/edr-freight-web/backoffice/src/components/fleet/FleetFormDialog.tsx

@@ -263,6 +263,14 @@ const FleetFormDialog = ({
     return map;
   }, [fields]);
 
+  // Emptying one of these means "unset the column", so it submits an explicit
+  // null instead of being dropped from the payload like other empty fields.
+  const clearableByName = useMemo(() => {
+    const map: Record<string, boolean> = {};
+    fields.forEach((f) => (map[f.name] = Boolean(f.clearable)));
+    return map;
+  }, [fields]);
+
   const handleSubmit = () => {
     // Hard gate: a driver record cannot be saved until its identity is verified
     // with Fayda. Mirrored server-side in DriversService.
@@ -280,8 +288,8 @@ const FleetFormDialog = ({
     const payload = Object.fromEntries(
       Object.entries(submitted)
         .map(([key, value]) => {
-          if (value === FLEET_SELECT_NONE || value === "")
-            return [key, undefined];
+          if (value === FLEET_SELECT_NONE || value === "" || value == null)
+            return [key, clearableByName[key] ? null : undefined];
           if (fieldTypeByName[key] === "number") {
             const num = Number(value);
             return [key, Number.isNaN(num) ? undefined : num];
@@ -357,6 +365,7 @@ const FleetFormDialog = ({
           }
           error={error}
           searchable
+          clearable={field.clearable}
           disabled={selectOptionsLoading || isDisabled}
           rightSection={
             selectOptionsLoading ? (

apps/edr-freight-web/backoffice/src/pages/fleet/config/resources.ts

@@ -47,6 +47,13 @@ export interface FleetFormFieldDef extends FormFieldDef {
    * truth at both render and submit.
    */
   derivedValue?: (values: Record<string, unknown>) => string;
+  /**
+   * Field can be emptied back to NULL. Empty values are normally dropped from
+   * the payload (so a PATCH leaves them untouched); a clearable field instead
+   * submits an explicit `null`, which is what actually unsets the column. Also
+   * renders a clear button on a `select`.
+   */
+  clearable?: boolean;
   /**
    * Field is owned by the Fayda identity — populated only by verification and
    * never hand-edited. Rendered disabled in the form.
@@ -327,6 +334,7 @@ export const FLEET_RESOURCES: FleetResourceConfig[] = [
         description: "Odd — Ethiopia → Djibouti runs",
         placeholder: "e.g. 8001",
         options: EXPORT_TRAIN_OPTIONS,
+        clearable: true,
       },
       {
         name: "importTrainNumber",
@@ -336,6 +344,8 @@ export const FLEET_RESOURCES: FleetResourceConfig[] = [
         placeholder: "e.g. 8002",
         derivedValue: (values) =>
           TRAIN_RUN_PAIRS[String(values.exportTrainNumber ?? "")] ?? "",
+        // Follows the export run to NULL when that is cleared.
+        clearable: true,
       },
       { name: "wagonNumber", label: "Wagon number", type: "text", required: true },
       { name: "wagonTypeId", label: "Wagon type", type: "select", required: true, dynamicOptions: "wagonTypes" },