fix If Property Value Is Null GetToStringValue will get System.NullRe…

…ferenceException #1
shps951023 · Mar 24, 2019 · 6152ad5 · 6152ad5
1 parent 31790e7
commit 6152ad5
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Showing 3 changed files with 19 additions and 31 deletions.
diff --git a/BenchmarkTest/Program.cs b/BenchmarkTest/Program.cs
@@ -32,7 +32,7 @@ public class BenchmarkBase
         public void ReflectionToString() => Data.Select(instance => {
             var type = instance.GetType();
             var props = type.GetProperties();
-            return props.ToDictionary(key => key.Name, value => value.GetValue(instance).ToString());
+            return props.ToDictionary(key => key.Name, value => value.GetValue(instance)?.ToString());
         }).ToList();
 
         [Benchmark()]

diff --git a/ValueGetter/ValueGetter.cs b/ValueGetter/ValueGetter.cs
@@ -11,17 +11,23 @@ public static partial class ValueGetter
     {
         /// <summary>
         /// Compiler Method Like:
-        /// <code>string GetterFunction(object i) => (i as MyClass).MyProperty1.ToString() ; </code>
+        /// <code>
+        ///     string GetterToStringFunction(object i) => GetterFunction(i).ToString() ; 
+        ///     object GetterFunction(object i) => (i as MyClass).MyProperty1 as object ;
+        /// </code>
         /// </summary>
         public static Dictionary<string, string> GetToStringValues<T>(this T instance) 
             => instance?.GetType().GetPropertiesFromCache().ToDictionary(key => key.Name, value => value.GetToStringValue<T>(instance));
 
         /// <summary>
         /// Compiler Method Like:
-        /// <code>string GetterFunction(object i) => (i as MyClass).MyProperty1.ToString() ; </code>
+        /// <code>
+        ///     string GetterToStringFunction(object i) => GetterFunction(i).ToString() ; 
+        ///     object GetterFunction(object i) => (i as MyClass).MyProperty1 as object ;
+        /// </code>
         /// </summary>
         public static string GetToStringValue<T>(this PropertyInfo propertyInfo, T instance)
-            => instance != null ? ValueGetterCache<T, string>.GetOrAddToStringFuntionCache(propertyInfo)(instance) : null;
+            => instance != null ? ValueGetterCache<T, object>.GetOrAddFunctionCache(propertyInfo)(instance)?.ToString() : null;
     }
 
     public static partial class ValueGetter
@@ -43,7 +49,6 @@ public static object GetObjectValue<T>(this PropertyInfo propertyInfo, T instanc
 
     internal partial class ValueGetterCache<TParam, TReturn>
     {
-        private static readonly ConcurrentDictionary<int, Func<TParam, TReturn>> ToStringFunctions = new ConcurrentDictionary<int, Func<TParam, TReturn>>();
         private static readonly ConcurrentDictionary<int, Func<TParam, TReturn>> Functions = new ConcurrentDictionary<int, Func<TParam, TReturn>>();
     }
 
@@ -68,31 +73,6 @@ internal partial class ValueGetterCache<TParam, TReturn>
         }
     }
 
-    internal partial class ValueGetterCache<TParam, TReturn>
-    {
-        internal static Func<TParam, TReturn> GetOrAddToStringFuntionCache(PropertyInfo propertyInfo)
-        {
-            var key = propertyInfo.MetadataToken;
-            if (ToStringFunctions.TryGetValue(key, out Func<TParam, TReturn> func))
-                return func;
-            return (ToStringFunctions[key] = GetCastObjectAndToStringFunction(propertyInfo));
-        }
-
-        private static Func<TParam, TReturn> GetCastObjectAndToStringFunction(PropertyInfo prop)
-        {
-            var propType = prop.PropertyType;
-            var toStringMethod = propType.GetMethods(BindingFlags.Public | BindingFlags.Instance).Where(p => p.Name == "ToString").First();
-
-            var instance = Expression.Parameter(typeof(TParam), "i");
-            var convert = Expression.TypeAs(instance, prop.DeclaringType);
-            var property = Expression.Property(convert, prop);
-            var tostring = Expression.Call(property, toStringMethod);
-            var lambda = Expression.Lambda<Func<TParam, TReturn>>(tostring, instance);
-
-            return lambda.Compile();
-        }
-    }
-
     public static partial class PropertyCacheHelper
     {
         private static readonly Dictionary<RuntimeTypeHandle, IList<PropertyInfo>> TypePropertiesCache = new Dictionary<RuntimeTypeHandle, IList<PropertyInfo>>();

diff --git a/ValueGetterTests/ToStringValueHelperTests.cs b/ValueGetterTests/ToStringValueHelperTests.cs
@@ -112,7 +112,7 @@ public void IssueForUpcastError()
         }
 
         [TestMethod]
-        public void PropNull()
+        public void IstanceIsNull()
         {
             MyClass data = null;
             var props = typeof(MyClass).GetProperties();
@@ -122,5 +122,13 @@ public void PropNull()
                 var result =  prop.GetObjectValue(data);
             }
         }
+
+        [TestMethod]
+        public void PropertyValueIsNull()
+        {
+            MyClass data = new MyClass { MyProperty2=null} ;
+            var result = data.GetToStringValues()["MyProperty2"] ; //System.NullReferenceException: 'Object reference not set to an instance of an object.'
+            Assert.IsNull(result);
+        }
     }
 }