## v0.9.16

- 增加 BaseRepository.AttachOnlyPrimary 方法，只附加实体的主键值；
> 在更新前使用可实现不查询数据库再更新、也可以实现更新时不更新值为 null 的字段
```csharp
class T {
    public int id { get; set; }
    public string name { get; set; }
    public string other { get; set; }
}
var item = new T { id = 1, name = "xx" };
fsql.GetRepository<T>().AttachOnlyPrimary(item).Update(item); //只更新 name
```
- 修复 Lambda 表达式中 DateTime.Now.ToString("yyyyMMdd") 不能直接执行的 bug；

Extensions/FreeSql.Extensions.BaseEntity/FreeSql.Extensions.BaseEntity.csproj

@@ -2,7 +2,7 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0</TargetFrameworks>
-        <Version>0.9.15</Version>
+        <Version>0.9.16</Version>
         <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
         <Authors>YeXiangQin</Authors>
         <Description>BaseEntity 是一种极简单的 CodeFirst 开发方式，特别对单表或多表CRUD，利用继承节省了每个实体类的重复属性（创建时间、ID等字段），软件删除等功能，进行 crud 操作时不必时常考虑仓储的使用.</Description>

Extensions/FreeSql.Extensions.JsonMap/FreeSql.Extensions.JsonMap.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 扩展包，可实现实体类属性为对象时，以JSON形式映射存储.</Description>

Extensions/FreeSql.Extensions.LazyLoading/FreeSql.Extensions.LazyLoading.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 扩展包，可实现【延时加载】属性.</Description>

FreeSql.DbContext/DbContext/DbContext.cs

@@ -129,6 +129,17 @@ namespace FreeSql
         /// <param name="data"></param>
         public void Attach<TEntity>(TEntity data) where TEntity : class => this.Set<TEntity>().Attach(data);
         public void AttachRange<TEntity>(IEnumerable<TEntity> data) where TEntity : class => this.Set<TEntity>().AttachRange(data);
+
+        /// <summary>
+        /// 附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+        /// </summary>
+        /// <typeparam name="TEntity"></typeparam>
+        /// <param name="data"></param>
+        public DbContext AttachOnlyPrimary<TEntity>(TEntity data) where TEntity : class
+        {
+            this.Set<TEntity>().AttachOnlyPrimary(data);
+            return this;
+        }
         #endregion
 
         #region Queue Action

FreeSql.DbContext/DbSet/DbSet.cs

@@ -162,6 +162,23 @@ namespace FreeSql
                 });
             }
         }
+        /// <summary>
+        /// 附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+        /// </summary>
+        /// <param name="data"></param>
+        public DbSet<TEntity> AttachOnlyPrimary(TEntity data)
+        {
+            if (data == null) return this;
+            var pkitem = (TEntity)Activator.CreateInstance(_entityType);
+            foreach (var pk in _db.Orm.CodeFirst.GetTableByEntity(_entityType).Primarys)
+            {
+                var colVal = _db.Orm.GetEntityValueWithPropertyName(_entityType, data, pk.CsName);
+                _db.Orm.SetEntityValueWithPropertyName(_entityType, pkitem, pk.CsName, colVal);
+            }
+            this.Attach(pkitem);
+            return this;
+        }
+
         /// <summary>
         /// 清空状态数据
         /// </summary>

FreeSql.DbContext/FreeSql.DbContext.csproj

@@ -2,7 +2,7 @@
 
     <PropertyGroup>
         <TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-        <Version>0.9.15</Version>
+        <Version>0.9.16</Version>
         <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
         <Authors>YeXiangQin</Authors>
         <Description>FreeSql is the most convenient ORM in dotnet. It supports Mysql, Postgresql, SqlServer, Oracle and Sqlite.</Description>

FreeSql.DbContext/FreeSql.DbContext.xml

@@ -39,6 +39,13 @@
             <typeparam name="TEntity"></typeparam>
             <param name="data"></param>
         </member>
+        <member name="M:FreeSql.DbContext.AttachOnlyPrimary``1(``0)">
+            <summary>
+            附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+            </summary>
+            <typeparam name="TEntity"></typeparam>
+            <param name="data"></param>
+        </member>
         <member name="P:FreeSql.DbContextOptions.EnableAddOrUpdateNavigateList">
             <summary>
             是否开启一对多，联级保存功能
@@ -57,6 +64,12 @@
             </summary>
             <param name="data"></param>
         </member>
+        <member name="M:FreeSql.DbSet`1.AttachOnlyPrimary(`0)">
+            <summary>
+            附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+            </summary>
+            <param name="data"></param>
+        </member>
         <member name="M:FreeSql.DbSet`1.FlushState">
             <summary>
             清空状态数据
@@ -156,6 +169,12 @@
             </summary>
             <param name="entity"></param>
         </member>
+        <member name="M:FreeSql.IBasicRepository`1.AttachOnlyPrimary(`0)">
+            <summary>
+            附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+            </summary>
+            <param name="data"></param>
+        </member>
         <member name="P:FreeSql.IUnitOfWork.Enable">
             <summary>
             是否启用工作单元

FreeSql.DbContext/Repository/Repository/BaseRepository.cs

@@ -140,6 +140,11 @@ namespace FreeSql
 
         public void Attach(TEntity data) => _db.Attach(data);
         public void Attach(IEnumerable<TEntity> data) => _db.AttachRange(data);
+        public IBasicRepository<TEntity> AttachOnlyPrimary(TEntity data)
+        {
+            _db.AttachOnlyPrimary(data);
+            return this;
+        }
         public void FlushState() => _dbset.FlushState();
 
         public TEntity InsertOrUpdate(TEntity entity)

FreeSql.DbContext/Repository/Repository/IBasicRepository.cs

@@ -21,6 +21,12 @@ namespace FreeSql
         /// <param name="entity"></param>
         void Attach(TEntity entity);
         void Attach(IEnumerable<TEntity> entity);
+        /// <summary>
+        /// 附加实体，并且只附加主键值，可用于不更新属性值为null或默认值的字段
+        /// </summary>
+        /// <param name="data"></param>
+        IBasicRepository<TEntity> AttachOnlyPrimary(TEntity data);
+
         int Update(TEntity entity);
         int Update(IEnumerable<TEntity> entitys);
         Task<int> UpdateAsync(TEntity entity);

FreeSql.Repository/FreeSql.Repository.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql Implementation of General Repository, Support MySql/SqlServer/PostgreSQL/Oracle/Sqlite, and read/write separation、and split table.</Description>
 		<PackageProjectUrl>https://github.com/2881099/FreeSql/wiki/Repository</PackageProjectUrl>

FreeSql.Tests/FreeSql.Tests.DbContext/RepositoryTests.cs

@@ -37,9 +37,13 @@ namespace FreeSql.Tests
             repos.Attach(item);
 
             item.Title = "xxx";
-            repos.Update(item);
+            repos.Update(item); //这行执行 UPDATE "AddUpdateInfo" SET "Title" = 'xxx' WHERE("Id" = '1942fb53-9700-411d-8895-ce4cecdf3257')
             Console.WriteLine(Newtonsoft.Json.JsonConvert.SerializeObject(item));
 
+            repos.Update(item); //这行不执行 SQL，未变化
+
+            repos.AttachOnlyPrimary(item).Update(item); //这行更新状态值，只有主键值存在，执行更新 set title = xxx
+
             Console.WriteLine(repos.UpdateDiy.Where(a => a.Id == item.Id).Set(a => a.Clicks + 1).ToSql());
             repos.UpdateDiy.Where(a => a.Id == item.Id).Set(a => a.Clicks + 1).ExecuteAffrows();
 

FreeSql.Tests/FreeSql.Tests/UnitTest1.cs

@@ -22,7 +22,7 @@ namespace FreeSql.Tests
     {
         public static T TryTo<T>(this string that)
         {
-            return default(T);
+            return (T)Internal.Utils.GetDataReaderValue(typeof(T), that);
         }
 
         public static string FormatDateTime()
@@ -407,6 +407,12 @@ namespace FreeSql.Tests
         public void Test1()
         {
 
+            var testrunsql1 =  g.mysql.Select<TaskBuild>().Where(a => a.OptionsEntity04 > DateTime.Now.AddDays(0).ToString("yyyyMMdd").TryTo<int>()).ToSql();
+            var testrunsql2 = g.pgsql.Select<TaskBuild>().Where(a => a.OptionsEntity04 > DateTime.Now.AddDays(0).ToString("yyyyMMdd").TryTo<int>()).ToSql();
+            var testrunsql3 = g.sqlserver.Select<TaskBuild>().Where(a => a.OptionsEntity04 > DateTime.Now.AddDays(0).ToString("yyyyMMdd").TryTo<int>()).ToSql();
+            var testrunsql4 = g.oracle.Select<TaskBuild>().Where(a => a.OptionsEntity04 > DateTime.Now.AddDays(0).ToString("yyyyMMdd").TryTo<int>()).ToSql();
+            var testrunsql5 = g.sqlite.Select<TaskBuild>().Where(a => a.OptionsEntity04 > DateTime.Now.AddDays(0).ToString("yyyyMMdd").TryTo<int>()).ToSql();
+
             var testssargs1 = "10100";
             var testformatsql1 = g.mysql.Select<TaskBuild>().Where(a => a.NamespaceName == $"1_{10100}").ToSql();
             var testorderbysql = g.mysql.Select<TaskBuild>().OrderByDescending(a => a.OptionsEntity04 + (a.score ?? 0)).ToSql();

FreeSql/FreeSql.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql is the most convenient ORM in dotnet. It supports Mysql, Postgresql, SqlServer, Oracle and Sqlite.</Description>

Providers/FreeSql.Provider.MySql/FreeSql.Provider.MySql.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net452</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 MySql 5.6</Description>

Providers/FreeSql.Provider.MySql/MySqlExpression.cs

@@ -83,7 +83,7 @@ namespace FreeSql.MySql
                             if (callExp.Method.DeclaringType.IsNumberType()) return "rand()";
                             break;
                         case "ToString":
-                            if (callExp.Object != null) return $"cast({getExp(callExp.Object)} as char)";
+                            if (callExp.Object != null) return callExp.Arguments.Count == 0 ? $"cast({getExp(callExp.Object)} as char)" : null;
                             break;
                     }
 
@@ -385,7 +385,7 @@ namespace FreeSql.MySql
                         break;
                     case "Equals": return $"({left} = {getExp(exp.Arguments[0])})";
                     case "CompareTo": return $"timestampdiff(microsecond,{args1},{left})";
-                    case "ToString": return $"date_format({left}, '%Y-%m-%d %H:%i:%s.%f')";
+                    case "ToString": return exp.Arguments.Count == 0 ? $"date_format({left}, '%Y-%m-%d %H:%i:%s.%f')" : null;
                 }
             }
             return null;

Providers/FreeSql.Provider.MySqlConnector/FreeSql.Provider.MySqlConnector.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 MySql 5.6</Description>

Providers/FreeSql.Provider.Oracle/FreeSql.Provider.Oracle.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 Oracle 11</Description>

Providers/FreeSql.Provider.Oracle/OracleExpression.cs

@@ -83,7 +83,7 @@ namespace FreeSql.Oracle
                             if (callExp.Method.DeclaringType.IsNumberType()) return "dbms_random.value";
                             break;
                         case "ToString":
-                            if (callExp.Object != null) return $"to_char({getExp(callExp.Object)})";
+                            if (callExp.Object != null) return callExp.Arguments.Count == 0 ? $"to_char({getExp(callExp.Object)})" : null;
                             break;
                     }
 
@@ -387,7 +387,7 @@ namespace FreeSql.Oracle
                         break;
                     case "Equals": return $"({left} = {getExp(exp.Arguments[0])})";
                     case "CompareTo": return $"extract(day from ({left}-({getExp(exp.Arguments[0])})))";
-                    case "ToString": return $"to_char({left},'YYYY-MM-DD HH24:MI:SS.FF6')";
+                    case "ToString": return exp.Arguments.Count == 0 ? $"to_char({left},'YYYY-MM-DD HH24:MI:SS.FF6')" : null;
                 }
             }
             return null;

Providers/FreeSql.Provider.PostgreSQL/FreeSql.Provider.PostgreSQL.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 PostgreSQL 9.5</Description>

Providers/FreeSql.Provider.PostgreSQL/PostgreSQLExpression.cs

@@ -88,7 +88,7 @@ namespace FreeSql.PostgreSQL
                             if (callExp.Method.DeclaringType.IsNumberType()) return "random()";
                             break;
                         case "ToString":
-                            if (callExp.Object != null) return $"({getExp(callExp.Object)})::varchar";
+                            if (callExp.Object != null) return callExp.Arguments.Count == 0 ? $"({getExp(callExp.Object)})::varchar" : null;
                             break;
                     }
 
@@ -496,7 +496,7 @@ namespace FreeSql.PostgreSQL
                         break;
                     case "Equals": return $"({left} = ({getExp(exp.Arguments[0])})::timestamp)";
                     case "CompareTo": return $"extract(epoch from ({left})::timestamp-({getExp(exp.Arguments[0])})::timestamp)";
-                    case "ToString": return $"to_char({left}, 'YYYY-MM-DD HH24:MI:SS.US')";
+                    case "ToString": return exp.Arguments.Count == 0 ? $"to_char({left}, 'YYYY-MM-DD HH24:MI:SS.US')" : null;
                 }
             }
             return null;

Providers/FreeSql.Provider.SqlServer/FreeSql.Provider.SqlServer.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net451</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 SqlServer 2005+，并根据版本适配分页方法：row_number 或 offset fetch next</Description>

Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs

@@ -87,7 +87,7 @@ namespace FreeSql.SqlServer
                             if (callExp.Method.DeclaringType.IsNumberType()) return "rand()";
                             break;
                         case "ToString":
-                            if (callExp.Object != null) return callExp.Object.Type.NullableTypeOrThis() == typeof(Guid) ? $"cast({getExp(callExp.Object)} as varchar(36))" : $"cast({getExp(callExp.Object)} as nvarchar)";
+                            if (callExp.Object != null) return callExp.Arguments.Count == 0 ? (callExp.Object.Type.NullableTypeOrThis() == typeof(Guid) ? $"cast({getExp(callExp.Object)} as varchar(36))" : $"cast({getExp(callExp.Object)} as nvarchar)") : null;
                             break;
                     }
 
@@ -367,7 +367,7 @@ namespace FreeSql.SqlServer
                         break;
                     case "Equals": return $"({left} = {getExp(exp.Arguments[0])})";
                     case "CompareTo": return $"datediff(second,{getExp(exp.Arguments[0])},{left})";
-                    case "ToString": return $"convert(varchar, {left}, 121)";
+                    case "ToString": return exp.Arguments.Count == 0 ? $"convert(varchar, {left}, 121)" : null;
                 }
             }
             return null;

Providers/FreeSql.Provider.Sqlite/FreeSql.Provider.Sqlite.csproj

@@ -2,7 +2,7 @@
 
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net45</TargetFrameworks>
-		<Version>0.9.15</Version>
+		<Version>0.9.16</Version>
 		<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
 		<Authors>YeXiangQin</Authors>
 		<Description>FreeSql 数据库实现，基于 Sqlite 3.0</Description>

Providers/FreeSql.Provider.Sqlite/SqliteExpression.cs

@@ -83,7 +83,7 @@ namespace FreeSql.Sqlite
                             if (callExp.Method.DeclaringType.IsNumberType()) return "random()";
                             break;
                         case "ToString":
-                            if (callExp.Object != null) return $"cast({getExp(callExp.Object)} as character)";
+                            if (callExp.Object != null) return callExp.Arguments.Count == 0 ? $"cast({getExp(callExp.Object)} as character)" : null;
                             break;
                     }
 
@@ -389,7 +389,7 @@ namespace FreeSql.Sqlite
                         break;
                     case "Equals": return $"({left} = {getExp(exp.Arguments[0])})";
                     case "CompareTo": return $"(strftime('%s',{left})-strftime('%s',{args1}))";
-                    case "ToString": return $"strftime('%Y-%m-%d %H:%M.%f',{left})";
+                    case "ToString": return exp.Arguments.Count == 0 ? $"strftime('%Y-%m-%d %H:%M.%f',{left})" : null;
                 }
             }
             return null;