CreateEqualCondition added to ExpressionUtility

VahidFarahmandian · Sep 28, 2023 · a2bab47 · a2bab47
1 parent 80affce
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diff --git a/01-Core/Jinget.Core/Utilities/Expressions/ExpressionUtility.cs b/01-Core/Jinget.Core/Utilities/Expressions/ExpressionUtility.cs
@@ -280,5 +280,53 @@ private static Expression GetBinaryExpression(MemberExpression left, ConstantExp
                 _ => throw new JingetException($"Operator of type {@operator} is not supported by Jinget!"),
             };
         }
+
+        public static Expression<Func<T, bool>> CreateEqualCondition<T, TValueType>(string propertyName, object value, string parameterName = "Param_0")
+        {
+            ParameterExpression parameter = Expression.Parameter(typeof(T), parameterName);
+
+            Type valueType = typeof(TValueType);
+
+            var rightExpression = Expression.Constant(value, valueType.IsNullable() ? Nullable.GetUnderlyingType(valueType) : valueType);
+
+            MemberExpression propertyAccess = GetMemberAccessExpression(parameter, propertyName, typeof(T));
+            if (valueType.IsNullable())
+            {
+                MemberExpression propertyValueAccess = GetMemberAccessExpression(parameter, $"{propertyName}.Value", typeof(T));
+                MemberExpression hasValueAccess = GetMemberAccessExpression(parameter, $"{propertyName}.HasValue", typeof(T));
+                return Expression.Lambda<Func<T, bool>>(
+                    Expression.Condition(hasValueAccess, Expression.Equal(propertyValueAccess, rightExpression), Expression.Constant(false)), parameter);
+            }
+
+            return Expression.Lambda<Func<T, bool>>(Expression.Equal(propertyAccess, rightExpression), parameter);
+        }
+
+        private static MemberExpression GetMemberAccessExpression(Expression expression, string members, Type type)
+        {
+            List<string> memberList = members.Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries).ToList();
+            string firstMember = memberList.First();
+            MemberExpression memberExpression = CreateMemberAccessExpression(type, expression, firstMember);
+
+            foreach (var item in memberList.Skip(1))
+            {
+                memberExpression = CreateMemberAccessExpression(((PropertyInfo)memberExpression.Member).PropertyType, memberExpression, item);
+            }
+            return memberExpression;
+        }
+
+        private static MemberExpression CreateMemberAccessExpression(Type type, Expression expression, string member)
+        {
+            var membersInfo = type.GetMember(member);
+            if (membersInfo.Any())
+            {
+                MemberInfo memberInfo = membersInfo.FirstOrDefault();
+                if (memberInfo != null)
+                    return Expression.MakeMemberAccess(expression, memberInfo);
+
+                throw new JingetException($"Jinget Says: {type.Name} does not {member} member.", 1000);
+            }
+
+            throw new JingetException($"Jinget Says: {type.Name} does not {member} member.", 1000);
+        }
     }
 }
diff --git a/Tests/Jinget.Core.Tests/Utilities/Expressions/ExpressionUtilityTests.cs b/Tests/Jinget.Core.Tests/Utilities/Expressions/ExpressionUtilityTests.cs
@@ -6,6 +6,7 @@
 using System.Linq;
 using Jinget.Core.Utilities.Expressions;
 using Jinget.Core.Types;
+using static iText.StyledXmlParser.Jsoup.Select.Evaluator;
 
 namespace Jinget.Core.ExtensionMethods.Expressions.Tests
 {
@@ -36,6 +37,15 @@ public void should_create_a_member_access_expression()
             Assert.AreEqual(expectedExpression.Type, result.Type);
         }
 
+        [TestMethod()]
+        public void should_create_a_equal_condition_expression()
+        {
+            Expression<Func<TestClass, bool>> expectedResult = x => x.Property1 == 1;
+            var result = ExpressionUtility.CreateEqualCondition<TestClass, int>("Property1", 1, "x");
+
+            Assert.AreEqual(expectedResult.Type, result.Type);
+        }
+
         #region null or empty filters
 
         [TestMethod]