Support native HasValue

Src/Asp.Net/SqlServerTest/Program.cs

@@ -18,7 +18,7 @@ namespace OrmTest
         static void Main(string[] args)
         {
             //    /***Unit Test***/
-            //new Select(1).Init();
+            new Select(1).Init();
             new Field(1).Init();
             new Where(1).Init();
             new Method(1).Init();

Src/Asp.Net/SqlServerTest/UnitTest/ExpressionTest/Select.cs

@@ -129,8 +129,9 @@ namespace OrmTest.UnitTest
                 "Select.single4 Error");
         }
 
-        private void single5(DateTime? p = null)
+        private void single5()
         {
+            var p =(DateTime?) DateTime.Now;
             Expression<Func<Student, object>> exp = it => p.HasValue;
             SqlServerExpressionContext expContext = new SqlServerExpressionContext();
             expContext.IsSingle = false;
@@ -138,7 +139,9 @@ namespace OrmTest.UnitTest
             var selectorValue = expContext.Result.GetString();
             var pars = expContext.Parameters;
             base.Check(
-                @"( [it].[SchoolId]<>'' AND [it].[SchoolId] IS NOT NULL )", null, selectorValue, null,
+                @"( @constant0<>'' AND @constant0 IS NOT NULL )", new List<SugarParameter>() {
+                    new SugarParameter("@constant0",p)
+                }, selectorValue, pars,
                 "Select.single4 Error");
         }
 

Src/Asp.Net/SqlSugar/ExpressionsToSql/ResolveItems/BaseResolve.cs

@@ -106,6 +106,7 @@ namespace SqlSugar
             }
             return null;
         }
+
         protected void AppendMember(ExpressionParameter parameter, bool? isLeft, object appendValue)
         {
 
@@ -197,6 +198,25 @@ namespace SqlSugar
                 this.Context.Result.Append(" " + ExpressionConst.Format1 + parameter.BaseParameter.Index);
             }
         }
+        protected string AppendParameter(object paramterValue)
+        {
+            string parameterName = this.Context.SqlParameterKeyWord + "constant" + this.Context.ParameterIndex;
+            this.Context.ParameterIndex++;;
+            this.Context.Parameters.Add(new SugarParameter(parameterName, paramterValue));
+            return parameterName;
+        }
+        protected void AppendNot(object Value)
+        {
+            var isAppend = !this.Context.Result.Contains(ExpressionConst.Format0);
+            if (isAppend)
+            {
+                this.Context.Result.Append("NOT");
+            }
+            else
+            {
+                this.Context.Result.Replace(ExpressionConst.Format0, "NOT");
+            }
+        }
 
         protected MethodCallExpressionArgs GetMethodCallArgs(ExpressionParameter parameter, Expression item)
         {
@@ -215,7 +235,6 @@ namespace SqlSugar
             };
             return methodCallExpressionArgs;
         }
-
         protected void ResolveNewExpressions(ExpressionParameter parameter, Expression item, string asName)
         {
             if (item.NodeType == ExpressionType.Constant)
@@ -366,18 +385,5 @@ namespace SqlSugar
                 Check.ThrowNotSupportedException(item.GetType().Name);
             }
         }
-
-        protected void AppendNot(object Value)
-        {
-            var isAppend = !this.Context.Result.Contains(ExpressionConst.Format0);
-            if (isAppend)
-            {
-                this.Context.Result.Append("NOT");
-            }
-            else
-            {
-                this.Context.Result.Replace(ExpressionConst.Format0, "NOT");
-            }
-        }
     }
 }

Src/Asp.Net/SqlSugar/ExpressionsToSql/ResolveItems/UnaryExpressionResolve.cs

@@ -60,6 +60,19 @@ namespace SqlSugar
                 var member = memberExpression.Expression as MemberExpression;
                 parameter.CommonTempData = CommonTempDataType.Result;
                 var isConst = member.Expression != null && member.Expression is ConstantExpression;
+                if (isConst)
+                {
+                    var paramterValue = ExpressionTool.DynamicInvoke(member);
+                    var paramterName= base.AppendParameter(paramterValue);
+                    var result = this.Context.DbMehtods.HasValue(new MethodCallExpressionModel()
+                    {
+                        Args = new List<MethodCallExpressionArgs>() {
+                        new MethodCallExpressionArgs() { IsMember=false, MemberName=paramterName, MemberValue=paramterValue } }
+                    });
+                    this.Context.Result.Append(result);
+                }
+                else
+                {
                     this.Expression = isConst ? member.Expression : member;
                     this.Start();
                     var methodParamter = isConst ? new MethodCallExpressionArgs() { IsMember = false } : new MethodCallExpressionArgs() { IsMember = true, MemberName = parameter.CommonTempData, MemberValue = null };
@@ -72,6 +85,7 @@ namespace SqlSugar
                     this.Context.Result.Append(result);
                     parameter.CommonTempData = null;
                 }
+            }
             else if (memberExpression.Type == PubConst.BoolType && isLogicOperator)
             {
                 Append(parameter, nodeType);