#241 QueryString DateTime / DateTimeOffset

Author: pwelter34

src/FluentRest/PostBuilder.cs

@@ -55,7 +55,15 @@ public TBuilder FormValue(string name, string? value)
     /// <exception cref="System.ArgumentNullException"><paramref name="name" /> is <see langword="null" />.</exception>
     public TBuilder FormValue<TValue>(string name, TValue? value)
     {
-        var v = value?.ToString();
+        var v = value switch
+        {
+            DateTime dateTime => dateTime.ToString("o"),
+            DateTimeOffset dateTimeOffset => dateTimeOffset.ToString("o"),
+#if NET6_0_OR_GREATER
+            DateOnly dateOnly => dateOnly.ToString("o"),
+#endif
+            _ => value?.ToString()
+        };
         return FormValue(name, v);
     }
 

src/FluentRest/QueryBuilder.cs

@@ -370,7 +370,16 @@ public TBuilder QueryString<TValue>(string name, TValue? value)
         if (name is null)
             throw new ArgumentNullException(nameof(name));
 
-        var v = value != null ? value.ToString() : string.Empty;
+        var v = value switch
+        {
+            DateTime dateTime => dateTime.ToString("o"),
+            DateTimeOffset dateTimeOffset => dateTimeOffset.ToString("o"),
+#if NET6_0_OR_GREATER
+            DateOnly dateOnly => dateOnly.ToString("o"),
+#endif
+            _ => value?.ToString()
+        };
+
         return QueryString(name, v);
     }
 
@@ -393,10 +402,7 @@ public TBuilder QueryStrings<TValue>(string name, IEnumerable<TValue>? values)
             return (TBuilder)this;
 
         foreach (var value in values)
-        {
-            var v = value != null ? value.ToString() : string.Empty;
-            QueryString(name, v);
-        }
+            QueryString(name, value);
 
         return (TBuilder)this;
     }

test/FluentRest.Tests/QueryBuilderTest.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Net.Http;
@@ -23,6 +24,21 @@ public void QueryStringNull()
         Assert.Equal("http://test.com/?Test=", uri.ToString());
     }
 
+    [Fact]
+    public void QueryStringDateTime()
+    {
+        var request = new HttpRequestMessage();
+        var builder = new QueryBuilder(request);
+
+        DateTime value = new(2025, 10, 15, 11, 11, 30, DateTimeKind.Utc);
+        builder.BaseUri("http://test.com/");
+        builder.QueryString("Test", value);
+
+        var uri = request.GetUrlBuilder();
+
+        Assert.Equal("http://test.com/?Test=2025-10-15T11%3A11%3A30.0000000Z", uri.ToString());
+    }
+
     [Fact]
     public void QueryStringMultipleValue()
     {