From fd799615f79d82f2276a3f17af325fe5ac1871ad Mon Sep 17 00:00:00 2001
From: Maksym Sadovnychyy <maksym.sadovnychyy@gmail.com>
Date: Fri, 18 Oct 2024 20:35:40 +0200
Subject: [PATCH] (bugfix): fix possible null ref exception

---
 .../Extensions/ExpressionExtensionsTests.cs   |  4 ++--
 .../Webapi/Models/PagedRequestTests.cs        | 13 +----------
 src/MaksIT.Core/MaksIT.Core.csproj            |  2 +-
 src/MaksIT.Core/Webapi/Models/PagedRequest.cs | 22 ++++++++++---------
 4 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/src/MaksIT.Core.Tests/Extensions/ExpressionExtensionsTests.cs b/src/MaksIT.Core.Tests/Extensions/ExpressionExtensionsTests.cs
index 3a1b58f..7998c52 100644
--- a/src/MaksIT.Core.Tests/Extensions/ExpressionExtensionsTests.cs
+++ b/src/MaksIT.Core.Tests/Extensions/ExpressionExtensionsTests.cs
@@ -10,7 +10,7 @@ public class ExpressionExtensionsTests {
   public void CombineWith_ShouldCombineTwoPredicates() {
     // Arrange
     Expression<Func<TestEntity, bool>> firstPredicate = x => x.Age > 18;
-    Expression<Func<TestEntity, bool>> secondPredicate = x => x.Name.StartsWith("A");
+    Expression<Func<TestEntity, bool>> secondPredicate = x => (x.Name ?? "").StartsWith("A");
 
     // Act
     var combinedPredicate = firstPredicate.CombineWith(secondPredicate);
@@ -25,7 +25,7 @@ public class ExpressionExtensionsTests {
   private class TestEntity {
     public Guid Id { get; set; }
     public int Age { get; set; }
-    public string Name { get; set; }
+    public string? Name { get; set; }
   }
 }
 
diff --git a/src/MaksIT.Core.Tests/Webapi/Models/PagedRequestTests.cs b/src/MaksIT.Core.Tests/Webapi/Models/PagedRequestTests.cs
index 685d632..d84b14d 100644
--- a/src/MaksIT.Core.Tests/Webapi/Models/PagedRequestTests.cs
+++ b/src/MaksIT.Core.Tests/Webapi/Models/PagedRequestTests.cs
@@ -4,17 +4,6 @@ using MaksIT.Core.Webapi.Models;
 namespace MaksIT.Core.Tests.Webapi.Models;
 
 public class PagedRequestTests {
-  [Fact]
-  public void BuildFilterExpression_ShouldReturnNull_WhenFilterIsEmpty() {
-    // Arrange
-    var request = new PagedRequest();
-
-    // Act
-    var result = request.BuildFilterExpression<TestEntity>(null);
-
-    // Assert
-    Assert.Null(result);
-  }
 
   [Fact]
   public void BuildFilterExpression_ShouldHandleEqualsOperator() {
@@ -131,6 +120,6 @@ public class PagedRequestTests {
 
 // Helper class for testing purposes
 public class TestEntity {
-  public string Name { get; set; }
+  public string? Name { get; set; }
   public int Age { get; set; }
 }
\ No newline at end of file
diff --git a/src/MaksIT.Core/MaksIT.Core.csproj b/src/MaksIT.Core/MaksIT.Core.csproj
index 35944e1..d28e5ee 100644
--- a/src/MaksIT.Core/MaksIT.Core.csproj
+++ b/src/MaksIT.Core/MaksIT.Core.csproj
@@ -8,7 +8,7 @@
 
     <!-- NuGet package metadata -->
     <PackageId>MaksIT.Core</PackageId>
-    <Version>1.1.3</Version>
+    <Version>1.1.4</Version>
     <Authors>Maksym Sadovnychyy</Authors>
     <Company>MAKS-IT</Company>
     <Product>MaksIT.Core</Product>
diff --git a/src/MaksIT.Core/Webapi/Models/PagedRequest.cs b/src/MaksIT.Core/Webapi/Models/PagedRequest.cs
index a8d5541..bb3b4df 100644
--- a/src/MaksIT.Core/Webapi/Models/PagedRequest.cs
+++ b/src/MaksIT.Core/Webapi/Models/PagedRequest.cs
@@ -91,16 +91,18 @@ namespace MaksIT.Core.Webapi.Models {
           expression = Expression.Not(expression);
         }
 
-        // Combine the current expression with the previous one using the correct operator
-        if (combinedExpression == null) {
-          combinedExpression = expression;
-        }
-        else if (i - 1 < operators.Count) // Ensure we don't exceed the operators list size
-        {
-          var operatorType = operators[i - 1];
-          combinedExpression = operatorType == "&&"
-              ? Expression.AndAlso(combinedExpression, expression)
-              : Expression.OrElse(combinedExpression, expression);
+        // Only combine expressions if the new expression is not null
+        if (expression != null) {
+          if (combinedExpression == null) {
+            combinedExpression = expression;
+          }
+          else if (i - 1 < operators.Count) // Ensure we don't exceed the operators list size
+          {
+            var operatorType = operators[i - 1];
+            combinedExpression = operatorType == "&&"
+                ? Expression.AndAlso(combinedExpression, expression)
+                : Expression.OrElse(combinedExpression, expression);
+          }
         }
       }