From c8e33b2981bd30eb3a96292514680f53d8368a57 Mon Sep 17 00:00:00 2001
From: Lev Boyarskiy <kawabata.sukan@gmail.com>
Date: Thu, 23 Apr 2026 19:56:12 -0700
Subject: [PATCH] Fix batch pricing API: flatten queryParams to top-level
 properties

Amazon changed their SP-API batch pricing endpoints contract on 2026-04-23.
The previously accepted nested queryParams format now returns HTTP 400:
  Requested MarketplaceId is invalid, unsupported, or does not exist.

The endpoints affected are:
  POST /batches/products/pricing/v0/itemOffers
  POST /batches/products/pricing/v0/listingOffers

Previously accepted (now broken):
  { uri: ..., method: GET, queryParams: { MarketplaceId: ATVPDKIKX0DER, ... } }

Now required (flat top-level):
  { uri: ..., method: GET, MarketplaceId: ATVPDKIKX0DER, ... }

Fix: mark QueryParams as [JsonIgnore] in both ItemOffersRequest and
ListingOffersRequest, and expose MarketplaceId, ItemCondition, CustomerType
as direct [JsonProperty] computed properties delegating to QueryParams.
This preserves the existing public API surface while correcting the wire format.
---
 .../ProductPricing/ItemOffersRequest.cs       | 24 +++++++------------
 .../ProductPricing/ListingOffersRequest.cs    | 15 ++++++++----
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/Source/FikaAmazonAPI/Parameter/ProductPricing/ItemOffersRequest.cs b/Source/FikaAmazonAPI/Parameter/ProductPricing/ItemOffersRequest.cs
index 6a14ecb0..eeaef0cc 100644
--- a/Source/FikaAmazonAPI/Parameter/ProductPricing/ItemOffersRequest.cs
+++ b/Source/FikaAmazonAPI/Parameter/ProductPricing/ItemOffersRequest.cs
@@ -28,25 +28,17 @@ public string Uri
         [JsonProperty("method")]
         public HttpMethodEnum HttpMethod { get; set; }
 
-        //[JsonProperty("headers")]
-        //public Dictionary<string, string> Headers { get; set; }
-
-        [JsonProperty("queryParams")]
+        // Amazon changed their batch API contract: query params must be serialized at the top level, not nested under "queryParams".
+        [JsonIgnore]
         public ParameterGetItemOffers QueryParams { get; set; }
 
-        ///// <summary>
-        ///// A marketplace identifier. Specifies the marketplace for which prices are returned.
-        ///// </summary>
-        //[DataMember(Name = "MarketplaceId")]
-        //public string MarketplaceId { get; set; }
-
-        //[DataMember(Name = "ItemCondition")]
-        //public ItemCondition ItemCondition { get; set; }
+        [JsonProperty("MarketplaceId")]
+        public string MarketplaceId => QueryParams?.MarketplaceId;
 
-        //[DataMember(Name = "CustomerType")]
-        //public CustomerType? CustomerType { get; set; }
+        [JsonProperty("ItemCondition")]
+        public ItemCondition ItemCondition => QueryParams?.ItemCondition ?? default;
 
-        //[JsonIgnore]
-        //public string Asin { get; set; }
+        [JsonProperty("CustomerType")]
+        public CustomerType? CustomerType => QueryParams?.CustomerType;
     }
 }
diff --git a/Source/FikaAmazonAPI/Parameter/ProductPricing/ListingOffersRequest.cs b/Source/FikaAmazonAPI/Parameter/ProductPricing/ListingOffersRequest.cs
index e3936736..a53c28c9 100644
--- a/Source/FikaAmazonAPI/Parameter/ProductPricing/ListingOffersRequest.cs
+++ b/Source/FikaAmazonAPI/Parameter/ProductPricing/ListingOffersRequest.cs
@@ -28,10 +28,17 @@ public string Uri
         [JsonProperty("method")]
         public HttpMethodEnum HttpMethod { get; set; }
 
-        //[JsonProperty("headers")]
-        //public Dictionary<string, string> Headers { get; set; }
-
-        [JsonProperty("queryParams")]
+        // Amazon changed their batch API contract: query params must be serialized at the top level, not nested under "queryParams".
+        [JsonIgnore]
         public ParameterGetListingOffers QueryParams { get; set; }
+
+        [JsonProperty("MarketplaceId")]
+        public string MarketplaceId => QueryParams?.MarketplaceId;
+
+        [JsonProperty("ItemCondition")]
+        public ItemCondition ItemCondition => QueryParams?.ItemCondition ?? default;
+
+        [JsonProperty("CustomerType")]
+        public CustomerType? CustomerType => QueryParams?.CustomerType;
     }
 }