Fix failure on REST requests with $filter and $orderby parameters

src/Core/Services/RestService.cs

@@ -71,7 +71,8 @@ RequestValidator requestValidator
             DatabaseObject dbObject = sqlMetadataProvider.EntityToDatabaseObject[entityName];
 
             QueryString? query = GetHttpContext().Request.QueryString;
-            string queryString = query is null ? string.Empty : GetHttpContext().Request.QueryString.ToString();
+            string queryString = query is null ? string.Empty : GetHttpContext().Request.QueryString.ToString()
+                .Replace("?%24", "?$").Replace("&%24", "&$");   //Add replacement in order to ensure '$' sign is present as expected only for the case where it is after a '?' or '&' signs.
 
             // Read the request body early so it can be used for downstream processing.
             string requestBody = string.Empty;

src/Service.Tests/Configuration/ConfigurationTests.cs

@@ -4224,6 +4224,41 @@ public async Task OpenApi_InteractiveSwaggerUI(
             }
         }
 
+        /// <summary>
+        /// End to end test that validates that REST requests with OData query
+        /// options $filter and $orderby succeed to ensure no regression can occur.
+        /// </summary>
+        [TestMethod]
+        [TestCategory(TestCategory.MSSQL)]
+        public async Task TestForRestRequestsWithFilterAndOrderbyParameters()
+        {
+            // The configuration file is constructed by merging hard-coded JSON strings to simulate the scenario where users manually edit the
+            // configuration file (instead of using CLI).
+            string configJson = TestHelper.AddPropertiesToJson(TestHelper.BASE_CONFIG, BOOK_ENTITY_JSON);
+            Assert.IsTrue(RuntimeConfigLoader.TryParseConfig(
+                configJson,
+                out RuntimeConfig deserializedConfig,
+                replacementSettings: new(),
+                connectionString: GetConnectionStringFromEnvironmentConfig(environment: TestCategory.MSSQL)));
+            string configFileName = "custom-config.json";
+            File.WriteAllText(configFileName, deserializedConfig.ToJson());
+            string[] args = new[]
+            {
+                    $"--ConfigFileName={configFileName}"
+            };
+
+            using (TestServer server = new(Program.CreateWebHostBuilder(args)))
+            using (HttpClient client = server.CreateClient())
+            {
+                // Act
+                using HttpRequestMessage restRequest = new(HttpMethod.Get, "/api/Book?$orderby=id desc&$filter=publisher_id eq 1234");
+                using HttpResponseMessage restResponse = await client.SendAsync(restRequest);
+
+                // Assert - Verify REST response
+                Assert.AreEqual(HttpStatusCode.OK, restResponse.StatusCode, "REST request to auto-generated entity should succeed");
+            }
+        }
+
         /// <summary>
         /// Test different loglevel values that are avaliable by deserializing RuntimeConfig with specified LogLevel
         /// and checks if value exists properly inside the deserialized RuntimeConfig.