Select() support for TimeSpan. Not complete LINQ support yet. Closes …

src/LinqTests/Acceptance/querying_against_timespan.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using JasperFx.Core;
+using Marten;
+using Marten.Testing.Documents;
+using Marten.Testing.Harness;
+using Shouldly;
+
+namespace LinqTests.Acceptance;
+
+public class querying_against_timespan : IntegrationContext
+{
+    public querying_against_timespan(DefaultStoreFixture fixture) : base(fixture)
+    {
+    }
+
+    [Fact]
+    public async Task select_to_time_span()
+    {
+        var span = TimeSpan.Parse("-20154.01:12:32");
+
+        var targets = Target.GenerateRandomData(10).ToArray();
+        var first = targets.First();
+        await theStore.BulkInsertDocumentsAsync(targets);
+
+        var results = await theSession.Query<Target>().Where(x => x.Id == first.Id).Select(x => x.HowLong)
+            .ToListAsync();
+        results.Single().ShouldBe(first.HowLong);
+    }
+}

src/Marten.Testing/Documents/Target.cs

@@ -94,6 +94,8 @@ public static Target Random(bool deep = false)
         target.Double = _random.NextDouble();
         target.Long = _random.Next() * 10000;
 
+        target.HowLong = TimeSpan.FromSeconds(target.Long);
+
         target.Date = DateTime.Today.AddDays(_random.Next(-10000, 10000));
 
         if (value > 15)
@@ -185,6 +187,8 @@ public Target()
     public List<string> StringList { get; set; }
 
     public Guid[] GuidArray { get; set; }
+
+    public TimeSpan HowLong { get; set; }
 }
 
 public class Address

src/Marten/Linq/Members/EnumAsIntegerMember.cs

@@ -1,4 +1,5 @@
 #nullable enable
+using System;
 using System.Linq.Expressions;
 using System.Reflection;
 using Marten.Exceptions;

src/Marten/Linq/Selectors/TimeSpanSelector.cs

@@ -0,0 +1,22 @@
+#nullable enable
+using System;
+using System.Data.Common;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Marten.Linq.Selectors;
+
+internal class TimeSpanSelector: ISelector<TimeSpan>
+{
+    public TimeSpan Resolve(DbDataReader reader)
+    {
+        var text = reader.GetString(0);
+        return TimeSpan.Parse(text);
+    }
+
+    public async Task<TimeSpan> ResolveAsync(DbDataReader reader, CancellationToken token)
+    {
+        var text = await reader.GetFieldValueAsync<string>(0, token).ConfigureAwait(false);
+        return TimeSpan.Parse(text);
+    }
+}

src/Marten/Linq/SqlGeneration/DataSelectClause.cs

@@ -64,13 +64,15 @@ public string[] SelectFields()
 
     public ISelector BuildSelector(IMartenSession session)
     {
+        if (typeof(T) == typeof(TimeSpan)) return new TimeSpanSelector();
+
         return new SerializationSelector<T>(session.Serializer);
     }
 
     public IQueryHandler<TResult> BuildHandler<TResult>(IMartenSession session, ISqlFragment statement,
         ISqlFragment currentStatement)
     {
-        var selector = new SerializationSelector<T>(session.Serializer);
+        var selector = typeof(T) == typeof(TimeSpan) ? (ISelector<T>)new TimeSpanSelector() : new SerializationSelector<T>(session.Serializer);
 
         return LinqQueryParser.BuildHandler<T, TResult>(selector, statement);
     }