- 增加 DbContext/Repository 比较变化方法 CompareState；

FreeSql.DbContext/DbContext/DbContext.cs

@@ -212,6 +212,17 @@ namespace FreeSql
             this.Set<TEntity>().AttachOnlyPrimary(data);
             return this;
         }
+
+        /// <summary>
+        /// 比较实体，计算出值发生变化的属性，以及属性变化的前后值
+        /// </summary>
+        /// <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+        /// <returns></returns>
+        public Dictionary<string, object[]> CompareState<TEntity>(TEntity newdata) where TEntity : class
+        {
+            CheckEntityTypeOrThrow(typeof(TEntity));
+            return this.Set<TEntity>().CompareState(newdata);
+        }
 #if net40
 #else
         public Task AddAsync<TEntity>(TEntity data) where TEntity : class

FreeSql.DbContext/DbSet/DbSet.cs

@@ -219,6 +219,31 @@ namespace FreeSql
             return this;
         }
 
+        /// <summary>
+        /// 比较实体，计算出值发生变化的属性，以及属性变化的前后值
+        /// </summary>
+        /// <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+        /// <returns></returns>
+        public Dictionary<string, object[]> CompareState(TEntity newdata)
+        {
+            if (newdata == null) return null;
+            if (_table.Primarys.Any() == false) throw new Exception($"不可比较，实体没有主键：{_db.OrmOriginal.GetEntityString(_entityType, newdata)}");
+            var key = _db.OrmOriginal.GetEntityKeyString(_entityType, newdata, false);
+            if (string.IsNullOrEmpty(key)) throw new Exception($"不可比较，未设置主键的值：{_db.OrmOriginal.GetEntityString(_entityType, newdata)}");
+            if (_states.TryGetValue(key, out var oldState) == false || oldState == null)
+                return _table.ColumnsByCs.ToDictionary(a => a.Key, a => new object[]
+                {
+                    _db.OrmOriginal.GetEntityValueWithPropertyName(_entityType, newdata, a.Key),
+                    null
+                });
+
+            return _db.OrmOriginal.CompareEntityValueReturnColumns(_entityType, oldState.Value, newdata, false).ToDictionary(a => a, a => new object[]
+            {
+                _db.OrmOriginal.GetEntityValueWithPropertyName(_entityType, newdata, a),
+                _db.OrmOriginal.GetEntityValueWithPropertyName(_entityType, oldState.Value, a)
+            });
+        }
+
         /// <summary>
         /// 清空状态数据
         /// </summary>

FreeSql.DbContext/FreeSql.DbContext.xml

@@ -62,6 +62,13 @@
             <typeparam name="TEntity"></typeparam>
             <param name="data"></param>
         </member>
+        <member name="M:FreeSql.DbContext.CompareState``1(``0)">
+            <summary>
+            比较实体，计算出值发生变化的属性，以及属性变化的前后值
+            </summary>
+            <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+            <returns></returns>
+        </member>
         <member name="P:FreeSql.DbContext.EntityChangeReport.ChangeInfo.BeforeObject">
             <summary>
             Type = Update 的时候，获取更新之前的对象
@@ -130,6 +137,13 @@
             </summary>
             <param name="data"></param>
         </member>
+        <member name="M:FreeSql.DbSet`1.CompareState(`0)">
+            <summary>
+            比较实体，计算出值发生变化的属性，以及属性变化的前后值
+            </summary>
+            <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+            <returns></returns>
+        </member>
         <member name="M:FreeSql.DbSet`1.FlushState">
             <summary>
             清空状态数据
@@ -314,6 +328,13 @@
             </summary>
             <param name="data"></param>
         </member>
+        <member name="M:FreeSql.IBaseRepository`1.CompareState(`0)">
+            <summary>
+            比较实体，计算出值发生变化的属性，以及属性变化的前后值
+            </summary>
+            <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+            <returns></returns>
+        </member>
         <member name="M:FreeSql.IBaseRepository`1.SaveMany(`0,System.String)">
             <summary>
             保存实体的指定 ManyToMany/OneToMany 导航属性（完整对比）<para></para>

FreeSql.DbContext/Repository/Repository/BaseRepository.cs

@@ -127,6 +127,7 @@ namespace FreeSql
             return this;
         }
         public void FlushState() => _dbset.FlushState();
+        public Dictionary<string, object[]> CompareState(TEntity newdata) => _dbset.CompareState(newdata);
 
         public virtual TEntity InsertOrUpdate(TEntity entity)
         {

FreeSql.DbContext/Repository/Repository/IBaseRepository.cs

@@ -58,6 +58,12 @@ namespace FreeSql
         /// </summary>
         /// <param name="data"></param>
         IBaseRepository<TEntity> AttachOnlyPrimary(TEntity data);
+        /// <summary>
+        /// 比较实体，计算出值发生变化的属性，以及属性变化的前后值
+        /// </summary>
+        /// <param name="newdata">最新的实体对象，它将与附加实体的状态对比</param>
+        /// <returns></returns>
+        Dictionary<string, object[]> CompareState(TEntity newdata);
 
         int Update(TEntity entity);
         int Update(IEnumerable<TEntity> entitys);

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

@@ -28,6 +28,7 @@ namespace FreeSql.Tests
             items[0].Title = "88";
             //items[1].Title = "88";
             items[2].Title = "88";
+            var changed = repos.CompareState(items[0]);
             int x = await repos.UpdateAsync(items);
         }