fix: Variant / Product Metadata making Product import fail when provided in csv input file

- fix: make Metadata Variant and Product Variant static columns use the new function, so they don't fail later with the create / update product zod schema
- chore: add tests for processAsJson fucntion

Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/core/utils/src/product/__tests__/csv-normalizer.spec.ts

@@ -1101,6 +1101,40 @@ describe("CSV processor", () => {
     `)
   })
 
+  describe("Variant Metadata column", () => {
+    it("should process variant metadata as JSON correctly", () => {
+      const csvRow = {
+        "Product Handle": "test-product",
+        "Variant Title": "Test Variant",
+        "Variant Metadata": '{ "key": "value", "number": 123 }',
+      }
+
+      const normalized = CSVNormalizer.preProcess(csvRow, 1)
+      const processor = new CSVNormalizer([normalized])
+      const result = processor.proccess()
+
+      expect(result.toCreate["test-product"].variants[0].metadata).toEqual({
+        key: "value",
+        number: 123,
+      })
+    })
+
+    it("should throw an error for invalid JSON in variant metadata", () => {
+      const csvRow = {
+        "Product Handle": "test-product",
+        "Variant Title": "Test Variant",
+        "Variant Metadata": 'invalid json',
+      }
+
+      const normalized = CSVNormalizer.preProcess(csvRow, 1)
+      const processor = new CSVNormalizer([normalized])
+
+      expect(() => processor.proccess()).toThrow(
+        'Row 1: Invalid value provided for "variant metadata". Expected a valid JSON string, received "invalid json"'
+      )
+    })
+  })
+
   describe("System-generated columns", () => {
     it("should ignore product timestamp columns during import", () => {
       const csvRow: Record<string, string | boolean | number> = {

packages/core/utils/src/product/csv-normalizer.ts

@@ -79,6 +79,28 @@ function processAsString<Output>(
   }
 }
 
+/**
+ * Process a column value as a json object
+ */
+function processAsJson<Output>(
+  inputKey: string,
+  outputKey: keyof Output
+): ColumnProcessor<Output> {
+  return (csvRow, _, rowNumber, output) => {
+    const value = csvRow[inputKey]
+    if (isPresent(value)) {
+      if (typeof value === 'string') {
+        try {
+          output[outputKey] = JSON.parse(value);
+        } catch (error) {
+          throw createError(rowNumber, `Invalid value provided for "${inputKey}". Expected a valid JSON string, received "${value}"`);
+        }
+      }
+    }
+    return undefined
+  }
+}
+
 /**
  * Processes a column value but ignores it (no-op processor for system-generated fields)
  */
@@ -193,7 +215,7 @@ const productStaticColumns: {
   ),
   "product weight": processAsNumber("product weight", "weight"),
   "product width": processAsNumber("product width", "width"),
-  "product metadata": processAsString("product metadata", "metadata"),
+  "product metadata": processAsJson("product metadata", "metadata"),
   "shipping profile id": processAsString(
     "shipping profile id",
     "shipping_profile_id"
@@ -257,7 +279,7 @@ const variantStaticColumns: {
   "variant height": processAsNumber("variant height", "height"),
   "variant length": processAsNumber("variant length", "length"),
   "variant material": processAsString("variant material", "material"),
-  "variant metadata": processAsString("variant metadata", "metadata"),
+  "variant metadata": processAsJson("variant metadata", "metadata"),
   "variant origin country": processAsString(
     "variant origin country",
     "origin_country"