Query.Contains allows whitespace value now

LiteDB.Tests/Issues/Issue2487_Tests.cs

@@ -0,0 +1,41 @@
+using FluentAssertions;
+
+using Xunit;
+
+namespace LiteDB.Tests.Issues;
+
+public class Issue2487_tests
+{
+    private class DataClass
+    {
+        [BsonId]
+        public int Id { get; set; }
+
+        public string Foo { get; set; }
+
+        public string Bar { get; set; }
+    }
+
+    [Fact]
+    public void Test_Contains_EmptyStrings()
+    {
+        using var engine = new ConnectionString(":memory:").CreateEngine();
+
+        using var db = new LiteDatabase(engine);
+        var collection = db.GetCollection<DataClass>("data");
+
+        collection.Insert(new DataClass { Foo = "bar", Bar = "abc" });
+        collection.Insert(new DataClass { Foo = " ", Bar = "def" });
+        collection.Insert(new DataClass { Foo = "fo bar", Bar = "def" });
+
+        var containsAction = () => collection.FindOne(x => x.Foo.Contains(" "));
+        containsAction.Should().NotThrow();
+
+        var def = containsAction();
+        def.Should().NotBeNull();
+        def.Bar.Should().Be("def");
+
+        var shouldExecute = () => engine.Query("data", Query.All(Query.Contains("Foo", " ")));
+        shouldExecute.Should().NotThrow();
+    }
+}

LiteDB/Client/Structures/Query.cs

@@ -1,7 +1,9 @@
 using LiteDB.Engine;
+
 using System;
 using System.Collections.Generic;
 using System.Linq;
+
 using static LiteDB.Constants;
 
 namespace LiteDB
@@ -83,7 +85,6 @@ public static BsonExpression GT(string field, BsonValue value)
             if (field.IsNullOrWhiteSpace()) throw new ArgumentNullException(nameof(field));
 
             return BsonExpression.Create($"{field} > {value ?? BsonValue.Null}");
-
         }
 
         /// <summary>
@@ -123,7 +124,7 @@ public static BsonExpression StartsWith(string field, string value)
         public static BsonExpression Contains(string field, string value)
         {
             if (field.IsNullOrWhiteSpace()) throw new ArgumentNullException(nameof(field));
-            if (value.IsNullOrWhiteSpace()) throw new ArgumentNullException(nameof(value));
+            if (value.IsNullOrEmpty()) throw new ArgumentNullException(nameof(value));
 
             return BsonExpression.Create($"{field} LIKE {(new BsonValue("%" + value + "%"))}");
         }

LiteDB/Utils/Extensions/StringExtensions.cs

@@ -16,6 +16,7 @@ public static bool IsNullOrWhiteSpace(this string str)
             return string.IsNullOrWhiteSpace(str);
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static bool IsNullOrEmpty(this string str)
         {
             return string.IsNullOrEmpty(str);