Add Subquery.WhereIF

Src/Asp.Net/SqlServerTest/Demos/1_Query.cs

@@ -114,7 +114,20 @@ namespace OrmTest.Demo
                     name = it.Name,
                     id = SqlFunc.Subqueryable<Student>().Where(s => s.Id == it.Id).Min(s => s.Id)
                 }).ToList();
-
+            string name = "a";
+            var getAll6666 = db.Queryable<Student>().Select(it =>
+            new
+            {
+                name = it.Name,
+                id = SqlFunc.Subqueryable<Student>().WhereIF(!string.IsNullOrEmpty(name), s=>s.Id==1).Min(s => s.Id)
+            }).ToList();
+            name = null;
+            var getAll66666 = db.Queryable<Student>().Select(it =>
+            new
+            {
+                name = it.Name,
+                id = SqlFunc.Subqueryable<Student>().WhereIF(!string.IsNullOrEmpty(name), s => s.Id == 1).Min(s => s.Id)
+            }).ToList();
         }
 
         private static void Async()

Src/Asp.Net/SqlSugar/ExpressionsToSql/Common/ErrorMessage.cs

@@ -44,5 +44,13 @@ namespace SqlSugar
                 return ErrorMessage.GetThrowMessage("Join {0} needs to be the same as {1} {2}", "多表查询存在别名不一致,请把{1}中的{2}改成{0}就可以了，特殊需求可以使用.Select((x,y)=>new{{ id=x.id,name=y.name}}).MergeTable().Orderby(xxx=>xxx.Id)功能将Select中的多表结果集变成单表，这样就可以不限制别名一样");
             }
         }
+
+        public static string WhereIFCheck
+        {
+            get
+            {
+                return ErrorMessage.GetThrowMessage("Subquery.WhereIF.IsWhere {0} not supported", "Subquery.WhereIF 第一个参数不支持表达式中的变量，只支持外部变量");
+            }
+        }
     }
 }

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/Items/SubWhereIF.cs

@@ -0,0 +1,62 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+
+namespace SqlSugar
+{
+    public class SubWhereIF : ISubOperation
+    {
+        public bool HasWhere
+        {
+            get; set;
+        }
+
+        public string Name
+        {
+            get { return "WhereIF"; }
+        }
+
+        public Expression Expression
+        {
+            get; set;
+        }
+
+        public int Sort
+        {
+            get
+            {
+                return 400;
+            }
+        }
+
+        public ExpressionContext Context
+        {
+            get; set;
+        }
+
+        public string GetValue(Expression expression)
+        {
+            var exp = expression as MethodCallExpression;
+            object value = null;
+            try
+            {
+                value = ExpressionTool.DynamicInvoke(exp.Arguments[0]);
+            }
+            catch 
+            {
+                Check.Exception(true, ErrorMessage.WhereIFCheck,exp.Arguments[0].ToString());
+            }
+            var isWhere= Convert.ToBoolean(value);
+            if (!Convert.ToBoolean(isWhere)) {
+                return "";
+            }
+            var argExp = exp.Arguments[1];
+            var result = "WHERE " + SubTools.GetMethodValue(Context, argExp, ResolveExpressType.WhereMultiple); ;
+            var selfParameterName = Context.GetTranslationColumnName((argExp as LambdaExpression).Parameters.First().Name) + UtilConstants.Dot;
+            result = result.Replace(selfParameterName, string.Empty);
+            return result;
+        }
+    }
+}

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/SubTools.cs

@@ -15,6 +15,7 @@ namespace SqlSugar
                                                 {
                                                     new SubSelect() { Context=Context },
                                                     new SubWhere(){ Context=Context },
+                                                    new SubWhereIF(){ Context=Context },
                                                     new SubAnd(){ Context=Context },
                                                     new SubAny(){ Context=Context },
                                                     new SubNotAny(){ Context=Context },

Src/Asp.Net/SqlSugar/ExpressionsToSql/Subquery/Subquerable.cs

@@ -13,6 +13,10 @@ namespace SqlSugar
         {
             return this;
         }
+        public Subqueryable<T> WhereIF(bool isWhere,Func<T, bool> expression)
+        {
+            return this;
+        }
         public Subqueryable<T> OrderBy(Func<T, object> expression)
         {
             return this;

Src/Asp.Net/SqlSugar/SqlSugar.csproj

@@ -106,6 +106,7 @@
     <Compile Include="ExpressionsToSql\Subquery\Items\SubSelectDefault.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubNotAny.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubTop.cs" />
+    <Compile Include="ExpressionsToSql\Subquery\Items\SubWhereIF.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Subquerable.cs" />
     <Compile Include="ExpressionsToSql\Subquery\Items\SubWhere.cs" />
     <Compile Include="ExpressionsToSql\Subquery\SubResolve.cs" />