Check for data collection type inside event subscriber functions added

Author: VladimirDimov

src/JQDT/Application/ApplicationBase.cs

@@ -151,6 +151,13 @@ private void PerformDataProcessorEventHandler(ref IQueryable<T> data, RequestInf
         {
             var dataAsObj = (object)data;
             eventHandler(ref dataAsObj, requestInfoModel);
+
+            // Assert that the data type remains proper inside the event subscriber function.
+            if (!typeof(IQueryable<T>).IsAssignableFrom(dataAsObj.GetType()))
+            {
+                throw new ArgumentException($"Inappropriate data collection type inside event subscriber function. The data collection type must be IQueryable<>.");
+            }
+
             data = (IQueryable<T>)dataAsObj;
         }
 

src/JQDT/DataProcessing/DataProcessBase.cs

@@ -84,6 +84,13 @@ private void ExecuteOnDataprocessingEvents(ref IQueryable<T> data, RequestInfoMo
         {
             var dataAsObj = (object)data;
             this.OnDataProcessingEvent(ref dataAsObj, requestInfoModel);
+
+            // Assert that the data type remains proper inside the event subscriber function.
+            if (!typeof(IQueryable<T>).IsAssignableFrom(dataAsObj.GetType()))
+            {
+                throw new ArgumentException($"Inappropriate data collection type inside event subscriber function. The data collection type must be IQueryable<>.");
+            }
+
             data = (IQueryable<T>)dataAsObj;
         }
 

src/Tests/UnitTests/Tests.UnitTests/JQDataTableAttributeMvcUnitTests.cs

@@ -77,6 +77,22 @@ public void AllEventsInsideMvcJQDTAttributeShouldBeCalledInCorrectOrder()
             Assert.IsTrue(expectedEventsCalls.SequenceEqual(calledEvents));
         }
 
+        [Test]
+        public void ExpectToThrowOnInappropriateDataTypeInsideEventSubscriberFunction()
+        {
+            var serviceLocatorMock = this.GetServiceLocatorMock();
+            var executeFunctionMock = this.GetExecuteFunctionProviderMock(serviceLocatorMock);
+            var contextMock = this.GetHttpContextMock();
+
+            var testAttr = new JQDataTableThrowExceptionTestAttribute(serviceLocatorMock.Object, executeFunctionMock.Object);
+
+            testAttr.OnActionExecuted(contextMock.Object);
+            var jsonResult = (JsonResult)contextMock.Object.Result;
+            var jsonResultString = jsonResult.Data.ToString();
+            
+            Assert.IsTrue(jsonResultString.Contains("error = Inappropriate data collection type inside event subscriber function. The data collection type must be IQueryable<>."));
+        }
+
         private Mock<IServiceLocator> GetServiceLocatorMock()
         {
             var serviceLocatorMock = new Mock<IServiceLocator>();
@@ -162,6 +178,19 @@ protected override IQueryable<T> GetData()
         }
     }
 
+    public class JQDataTableThrowExceptionTestAttribute : JQDataTableAttribute
+    {
+        internal JQDataTableThrowExceptionTestAttribute(IServiceLocator serviceLocator, IExecuteFunctionProvider<ActionExecutedContext> executeFunctionProvider)
+            : base(serviceLocator, executeFunctionProvider)
+        {
+        }
+
+        public override void OnDataProcessed(ref object data, RequestInfoModel requestInfoModel)
+        {
+            data = new List<IntModel>();
+        }
+    }
+
     public class JQDataTableTestAttribute : JQDataTableAttribute
     {
         private readonly List<string> calledEvents;