NXC-301: Update ToQueryString and usage

src/Nexus.Crypto.SDK/NexusAPIService.cs

@@ -63,15 +63,15 @@ public async Task<CustomResultHolder<PagedResult<GetBalanceMutation>>> GetBalanc
         Dictionary<string, string> queryParams)
     {
         return await GetAsync<CustomResultHolder<PagedResult<GetBalanceMutation>>>(
-            $"balances/hotwallet/mutations{CreateUriQuery(queryParams)}",
+            $"balances/hotwallet/mutations{ToQueryString(queryParams)}",
             ApiVersion1_2);
     }
 
     public async Task<CustomResultHolder<PagedResult<GetMail>>> GetMails(
         Dictionary<string, string> queryParams)
     {
         return await GetAsync<CustomResultHolder<PagedResult<GetMail>>>(
-            $"mail{CreateUriQuery(queryParams)}",
+            $"mail{ToQueryString(queryParams)}",
             ApiVersion1_2);
     }
 
@@ -84,14 +84,14 @@ public async Task<CustomResultHolder<PagedResult<GetTransaction>>> GetBrokerTran
         Dictionary<string, string> queryParams)
     {
         return await GetAsync<CustomResultHolder<PagedResult<GetTransaction>>>(
-            $"transaction{CreateUriQuery(queryParams)}", ApiVersion1_2);
+            $"transaction{ToQueryString(queryParams)}", ApiVersion1_2);
     }
 
     public async Task<CustomResultHolder<TotalsResult<TransactionTotals>>> GetBrokerTransactionTotals(
         Dictionary<string, string> queryParams)
     {
         return await GetAsync<CustomResultHolder<TotalsResult<TransactionTotals>>>(
-            $"transaction/totals{CreateUriQuery(queryParams)}", ApiVersion1_2);
+            $"transaction/totals{ToQueryString(queryParams)}", ApiVersion1_2);
     }
 
     public async Task<CustomResultHolder<PagedResult<GetTransfer>>> GetTransfers(GetTransfersRequest? request = null)
@@ -150,7 +150,7 @@ public async Task<CustomResultHolder<PagedResult<CustomerBankAccountResponse>>>
         string customerCode, Dictionary<string, string> queryParams)
     {
         return await GetAsync<CustomResultHolder<PagedResult<CustomerBankAccountResponse>>>(
-            $"customer/{customerCode}/bankaccounts{CreateUriQuery(queryParams)}",
+            $"customer/{customerCode}/bankaccounts{ToQueryString(queryParams)}",
             ApiVersion1_2);
     }
 

src/Nexus.Crypto.SDK/QueryParameterHelper.cs

@@ -1,4 +1,4 @@
-using System.Globalization;
+using System.Globalization;
 using System.Reflection;
 
 namespace Nexus.Crypto.SDK;
@@ -11,13 +11,22 @@ public static string ToQueryString(object? obj)
 
         var properties = obj.GetType()
             .GetProperties(BindingFlags.Public | BindingFlags.Instance)
-            .Where(p => p.GetValue(obj) != null)
-            .Select(p =>
-                $"{Uri.EscapeDataString(ToCamelCase(p.Name))}={Uri.EscapeDataString(p.GetValue(obj)?.ToString()!)}");
+            .Select(p => (Key: ToCamelCase(p.Name), Value: p.GetValue(obj)))
+            .Where(kv => kv.Value != null)
+            .Select(kv =>
+                $"{Uri.EscapeDataString(kv.Key)}={Uri.EscapeDataString(FormatValue(kv.Value!))}");
 
         return string.Join("&", properties);
     }
 
+    private static string FormatValue(object value) => value switch
+    {
+        DateTime dt => dt.ToString("O", CultureInfo.InvariantCulture),
+        DateTimeOffset dto => dto.ToString("O", CultureInfo.InvariantCulture),
+        IFormattable f => f.ToString(null, CultureInfo.InvariantCulture),
+        _ => value.ToString()!
+    };
+
     private static string ToCamelCase(string name)
     {
         if (string.IsNullOrEmpty(name) || char.IsLower(name[0]))

src/Nexus.Crypto.SDK/Services/BaseService.cs

@@ -1,4 +1,6 @@
-using System.Net.Http.Json;
+using System.Globalization;
+using System.Net.Http.Json;
+using System.Reflection;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Nexus.Crypto.SDK.Models;
@@ -154,30 +156,58 @@ public async Task<TResponse> DeleteAsync<TResponse>(string endPoint, string apiV
     }
 
     /// <summary>
-    /// Take Dictionary of query parameters and creates the query string to paste to the URI.
-    /// Prepends the '?'. When the dictionary is empty, returns an empty string;
+    /// Returns a query string of the given dictionary, starting with ?
     /// </summary>
-    /// <param name="queryParams"></param>
+    /// <param name="dict"></param>
     /// <returns></returns>
-    public static string CreateUriQuery(Dictionary<string, string> queryParams)
+    public static string ToQueryString(Dictionary<string, string> dict)
     {
-        var query = string.Empty;
+        var queryStrings = new List<string>();
 
-        foreach (var p in queryParams)
+        foreach (var (key, value) in dict)
         {
-            if (query == string.Empty)
+            if (!string.IsNullOrWhiteSpace(key) && !string.IsNullOrWhiteSpace(value))
             {
-                query += "?";
-            }
-            else
-            {
-                query += "&";
+                queryStrings.Add($"{Uri.EscapeDataString(ToCamelCase(key))}={Uri.EscapeDataString(value)}");
             }
+        }
+
+        if (queryStrings.Count > 0)
+        {
+            return "?" + string.Join("&", queryStrings);
+        }
+
+        return string.Empty;
+    }
+
+    /// <summary>
+    /// Returns a query string of the given object, starting with ?
+    /// </summary>
+    /// <param name="obj"></param>
+    /// <returns></returns>
+    public static string ToQueryString(object? obj)
+    {
+        if (obj == null) return string.Empty;
+
+        var properties = obj.GetType()
+            .GetProperties(BindingFlags.Public | BindingFlags.Instance)
+            .Where(p => p.GetValue(obj) != null)
+            .Select(p =>
+                $"{Uri.EscapeDataString(ToCamelCase(p.Name))}={Uri.EscapeDataString(p.GetValue(obj)?.ToString()!)}");
 
-            query += $"{p.Key}={p.Value}";
+        if (properties.Any())
+        {
+            return "?" + string.Join("&", properties);
         }
 
-        return query;
+        return string.Empty;
     }
 
+    private static string ToCamelCase(string name)
+    {
+        if (string.IsNullOrEmpty(name) || char.IsLower(name[0]))
+            return name;
+
+        return char.ToLower(name[0], CultureInfo.InvariantCulture) + name[1..];
+    }
 }

src/Nexus.Crypto.SDK/Services/CustomerPersonService.cs

@@ -16,7 +16,7 @@ public Task<CustomResultHolder<PersonResponse>> CreateCustomerPerson(string cust
 
     public Task<CustomResultHolder<PagedResult<PersonResponse>>> GetCustomerPersons(string customerCode, Dictionary<string, string> queryParams)
     {
-        var url = $"customer/{customerCode}/person" + BaseService.CreateUriQuery(queryParams);
+        var url = $"customer/{customerCode}/person" + BaseService.ToQueryString(queryParams);
         return service.GetAsync<CustomResultHolder<PagedResult<PersonResponse>>>(
             url,
             BaseService.ApiVersion1_2);

src/Nexus.Crypto.SDK/Services/CustomerService.cs

@@ -30,7 +30,7 @@ public async Task<CustomResultHolder<GetCustomer>> GetCustomer(string customerCo
     public async Task<CustomResultHolder<PagedResult<GetCustomer>>> GetCustomers(Dictionary<string, string> queryParams)
     {
         return await service.GetAsync<CustomResultHolder<PagedResult<GetCustomer>>>(
-            $"customer{BaseService.CreateUriQuery(queryParams)}",
+            $"customer{BaseService.ToQueryString(queryParams)}",
             BaseService.ApiVersion1_2);
     }
 

src/Nexus.Crypto.SDK/Services/DocumentStoreRecordService.cs

@@ -45,7 +45,7 @@ public Task<CustomResultHolder<PagedResult<DocumentStoreRecordResponse>>> Get(st
     {
         queryParams["customerCode"] = customerCode;
 
-        var url = DocumentStoreRecordListUrl + BaseService.CreateUriQuery(queryParams);
+        var url = DocumentStoreRecordListUrl + BaseService.ToQueryString(queryParams);
         return service.GetAsync<CustomResultHolder<PagedResult<DocumentStoreRecordResponse>>>(url,
             BaseService.ApiVersion1_2);
     }

src/Nexus.Crypto.SDK/Services/DocumentStoreTypeService.cs

@@ -26,7 +26,7 @@ public Task<CustomResultHolder<DocumentStoreTypeResponse>> GetByCode(string docu
 
     public Task<CustomResultHolder<PagedResult<DocumentStoreTypeResponse>>> Get(Dictionary<string, string> queryParams)
     {
-        var url = DocumentTypeUrl + BaseService.CreateUriQuery(queryParams);
+        var url = DocumentTypeUrl + BaseService.ToQueryString(queryParams);
         return service.GetAsync<CustomResultHolder<PagedResult<DocumentStoreTypeResponse>>>(url, BaseService.ApiVersion1_2);
     }
 

tests/Nexus.Crypto.SDK.Tests/NexusLabelApiSdkTests.cs

@@ -262,8 +262,7 @@ public async Task GetMails_Success()
 
         _logicHelper.MockResponseHandler.AddMockResponse(
             new HttpRequestMessage(HttpMethod.Get, new Uri(
-                "https://api.quantoznexus.com/mail?startDate=2020-06-21T16:24:09Z" +
-                "&endDate=2022-06-21T16:24:09Z&accountCode=CJABM2HM&customerCode=NLTEST&status=ReadyToSend&type=TransactionToBeReturned"))
+                "https://api.quantoznexus.com/mail?startDate=2020-06-21T16%3A24%3A09Z&endDate=2022-06-21T16%3A24%3A09Z&accountCode=CJABM2HM&customerCode=NLTEST&status=ReadyToSend&type=TransactionToBeReturned"))
             {
                 Headers = { { "api_version", "1.2" } }
             },
@@ -273,7 +272,7 @@ public async Task GetMails_Success()
             });
 
 
-        var response = await _logicHelper.ApiService.GetMails(new System.Collections.Generic.Dictionary<string, string>
+        var response = await _logicHelper.ApiService.GetMails(new Dictionary<string, string>
         {
             { "startDate", "2020-06-21T16:24:09Z" },
             { "endDate", "2022-06-21T16:24:09Z" },
@@ -778,7 +777,7 @@ public async Task GetCustomers_Success()
         _logicHelper.MockResponseHandler.AddMockResponse(
             new HttpRequestMessage(HttpMethod.Get,
                 new Uri(
-                    "https://api.quantoznexus.com/customer?startDate=2021-01-01T00:00:01Z&endDate=2022-01-01T00:00:03Z&status=Active"))
+                    "https://api.quantoznexus.com/customer?startDate=2021-01-01T00%3A00%3A01Z&endDate=2022-01-01T00%3A00%3A03Z&status=Active"))
             {
                 Headers = { { "api_version", "1.2" } }
             },

tests/Nexus.Crypto.SDK.Tests/QueryParameterHelperTests.cs

@@ -1,5 +1,8 @@
-namespace Nexus.Crypto.SDK.Tests;
+namespace Nexus.Crypto.SDK.Tests;
 
+using System;
+using System.Globalization;
+using System.Threading;
 using Xunit;
 
 public class QueryParameterHelperTests
@@ -19,6 +22,18 @@ private class TestObject
         public TestEnum? EnumValue { get; set; }
     }
 
+    private class NumericObject
+    {
+        public decimal Price { get; set; }
+        public double Rate { get; set; }
+    }
+
+    private class DateObject
+    {
+        public DateTime CreatedAt { get; set; }
+        public DateTimeOffset UpdatedAt { get; set; }
+    }
+
     [Fact]
     public void ToQueryString_NullObject_ReturnsEmptyString()
     {
@@ -83,4 +98,43 @@ public void ToQueryString_ObjectWithNullProperties_IgnoresNullProperties()
         // Assert
         Assert.Equal("name=Alice&age=0", result);
     }
+
+    [Fact]
+    public void ToQueryString_DecimalAndDouble_UsesInvariantCulture()
+    {
+        // Arrange
+        var obj = new NumericObject { Price = 1.5m, Rate = 2.75 };
+        var originalCulture = Thread.CurrentThread.CurrentCulture;
+        Thread.CurrentThread.CurrentCulture = new CultureInfo("de-DE"); // uses ',' as decimal separator
+
+        try
+        {
+            // Act
+            var result = QueryParameterHelper.ToQueryString(obj);
+
+            // Assert — values must contain '.' not ','
+            Assert.Equal("price=1.5&rate=2.75", result);
+        }
+        finally
+        {
+            Thread.CurrentThread.CurrentCulture = originalCulture;
+        }
+    }
+
+    [Fact]
+    public void ToQueryString_DateTime_UsesIso8601()
+    {
+        // Arrange
+        var dt = new DateTime(2024, 6, 15, 10, 30, 0, DateTimeKind.Utc);
+        var dto = new DateTimeOffset(2024, 6, 15, 10, 30, 0, TimeSpan.Zero);
+        var obj = new DateObject { CreatedAt = dt, UpdatedAt = dto };
+
+        // Act
+        var result = QueryParameterHelper.ToQueryString(obj);
+
+        // Assert — round-trip "O" format; URI-encoded '+' becomes '%2B', ':' becomes '%3A'
+        Assert.Contains("createdAt=", result);
+        Assert.Contains("updatedAt=", result);
+        Assert.Contains("2024", result);
+    }
 }

tests/Nexus.Crypto.SDK.Tests/TransactionControllerTests.cs

@@ -82,9 +82,7 @@ public async Task GetTransactions_Success()
                 ";
 
         _logicHelper.MockResponseHandler.AddMockResponse(
-            new HttpRequestMessage(HttpMethod.Get, new Uri("https://api.quantoznexus.com/transaction?status=BLOCKED|PAYOUTONHOLD" +
-                "&customer=NL51INGB7243913512&customerIsHighrisk=false&customerIsBusiness=False&customerTrustlevel=Trusted&customerStatus=Active" +
-                "&startDate=2020-06-04T14:52:41Z&endDate=2022-06-04T14:52:41Z&type=SELL&isSettled=false"))
+            new HttpRequestMessage(HttpMethod.Get, new Uri("https://api.quantoznexus.com/transaction?status=BLOCKED%7CPAYOUTONHOLD&customer=NL51INGB7243913512&customerIsHighrisk=false&customerIsBusiness=False&customerTrustlevel=Trusted&customerStatus=Active&startDate=2020-06-04T14%3A52%3A41Z&endDate=2022-06-04T14%3A52%3A41Z&type=SELL&isSettled=false"))
             {
                 Headers = {
                     { "api_version", "1.2" }