ORM框架 EF - code first 的封装
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Code first 是Microsoft Entity Framework中的一种模式，CodeFirst不会有可视化的界面来进行拖动编辑DataBase-Entity，但会以一个类来进行对数据表关系的描述，以及对所有实体类的描述，优势在于，代码更加地简洁，文件目录更加清晰，也更加便于维护。
直接用实体关系类进行操作，最后SaveChanges，无可厚非，当然可以了，但是，对于一个追求更加简便，更加抽象的程序员来说，无限的封装似乎是一种追求吧，废话不多说，这里直接上EF_Helper_DG的代码->
首先示例性地来一个实体关系类，以便于后面的帮助类的对比，当然，这个类也是不可或缺的。
DBEntity_DG（习惯性地起名）
1 namespace QX_Frame.DAL.Service 2 { 3 using System.Data.Entity; 4 using QX_Frame.Model; 5 6 public partial class DBEntity_DG : DbContext 7 { 8 public DBEntity_DG() 9 : base("name=DBEntity_DG") 10 { 11 } 12 13 public virtual DbSet<tb_Class> tb_Class { get; set; } 14 public virtual DbSet<tb_User> tb_User { get; set; } 15 16 protected override void OnModelCreating(DbModelBuilder modelBuilder) 17 { 18 modelBuilder.Entity<tb_Class>() 19 .Property(e => e.Name) 20 .IsFixedLength(); 21 22 modelBuilder.Entity<tb_Class>() 23 .HasMany(e => e.tb_User) 24 .WithRequired(e => e.tb_Class) 25 .HasForeignKey(e => e.ClassId) 26 .WillCascadeOnDelete(false); 27 28 modelBuilder.Entity<tb_User>() 29 .Property(e => e.Name) 30 .IsFixedLength(); 31 } 32 } 33 }
然后，我们来上正菜 EF_DBEntity_DG
1 using LinqKit; //AsExpandable() in linqkit.dll 2 using System; 3 using System.Collections.Generic; 4 using System.IO; 5 using System.Linq; 6 using System.Linq.Expressions; 7 using System.Data.Entity; 8 using QX_Frame.Helper_DG_Framework_4_6; 9 10 namespace QX_Frame.DAL.Service 11 { 12 /* time:2016-10-30 15:26:05 13 author:qixiao 14 */ 15 16 #region The EF_DBEntity_DG visual Interface 17 18 public interface IEF_DBEntity_DG 19 { 20 Boolean IsAdd<T>(T entity); 21 Boolean IsAdd<T>(T entity, out T outEntity); 22 Boolean IsAdd<T>(List<T> entities); 23 24 Boolean IsUpdate<T>(T entity); 25 Boolean IsUpdate<T>(T entity, out T outEntity); 26 27 Boolean IsDelete<T>(T entity); 28 Boolean IsDelete<T>(List<T> entities); 29 Boolean IsDelete<T>(Expression<Func<T, bool>> deleteWhere); 30 31 T selectSingle<T>(Expression<Func<T, Boolean>> selectWhere); 32 33 List<T> selectAll<T>(); 34 List<T> selectAll<T>(out int Count); 35 List<T> selectAll<T>(Expression<Func<T, T>> orderBy, Boolean isDESC = false); 36 List<T> selectAll<T>(Expression<Func<T, T>> orderBy, out int Count, Boolean isDESC = false); 37 List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere); 38 List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere, out int Count); 39 List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere, Expression<Func<T, T>> orderBy, Boolean isDESC = false); 40 List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere, Expression<Func<T, T>> orderBy, out int Count, Boolean isDESC = false); 41 42 List<T> selectAllPaging<T>(int pageIndex, int pageSize); 43 List<T> selectAllPaging<T>(int pageIndex, int pageSize, out int Count); 44 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, Boolean>> selectWhere); 45 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, Boolean>> selectWhere, out int Count); 46 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, T>> orderBy, Boolean isDESC = false); 47 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, T>> orderBy, out int Count, Boolean isDESC = false); 48 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, Boolean>> selectWhere, Expression<Func<T, T>> orderBy, Boolean isDESC = false); 49 List<T> selectAllPaging<T>(int pageIndex, int pageSize, Expression<Func<T, Boolean>> selectWhere, Expression<Func<T, T>> orderBy, out int Count, Boolean isDESC = false); 50 } 51 52 #endregion 53 54 public abstract class EF_DBEntity_DG 55 { 56 /*the singleton DBEntity_DG */ 57 /// <summary> 58 /// The DBEntity_DG is must be named: DBEntity_DG 59 /// </summary> 60 private volatile static DBEntity_DG db = null; 61 62 #region The Singleton to new DBEntity_DG 63 private static readonly object lockHelper = new object(); 64 static EF_DBEntity_DG() 65 { 66 if (db == null) 67 { 68 lock (lockHelper) 69 { 70 if (db == null) 71 db = new DBEntity_DG(); 72 } 73 } 74 //close the Validate of EF OnSaveEnabled 75 db.Configuration.ValidateOnSaveEnabled = false; 76 } 77 #endregion 78 79 /// <summary> 80 /// Give the Error Log support 81 /// </summary> 82 /// <param name="logText">LogText</param> 83 /// <param name="isAppend">The Log Text isAppend or Cover</param> 84 private static void Log_DG(string logText, string logTitle = "DBEntity_DG Error", Boolean isAppend = true) 85 { 86 string LogLocation_DG = @"Log_QX_Frame/Log_QX_Frame_Error/"; 87 try 88 { 89 LogLocation_DG = Config_Helper_DG.AppSetting_Get("Log_Location_Error_DG"); 90 } 91 catch (Exception) 92 { 93 LogLocation_DG = @"Log_QX_Frame/Log_QX_Frame_Error/"; 94 } 95 if (!Directory.Exists(LogLocation_DG)) 96 { 97 Directory.CreateDirectory(LogLocation_DG); 98 } 99 using (StreamWriter log = new StreamWriter(LogLocation_DG + "Log_" + DateTime.Now.Year + DateTime.Now.Month + DateTime.Now.Day + ".Log", isAppend)) 100 { 101 log.WriteLine(); 102 log.WriteLine(DateTime_Helper_DG.Get_DateTime_Now_24HourType() + " -------" + logTitle + " Log !--------------------"); 103 log.WriteLine(); 104 log.WriteLine(logText); 105 } 106 } 107 108 #region Add 109 110 public static Boolean IsAdd<T>(T entity) where T : class 111 { 112 try 113 { 114 db.Entry<T>(entity).State = EntityState.Added; 115 return db.SaveChanges() > 0; 116 } 117 catch (Exception ex) 118 { 119 Log_DG(ex.ToString()); 120 return false; 121 } 122 } 123 public static Boolean IsAdd<T>(T entity, out T outEntity) where T : class 124 { 125 try 126 { 127 db.Entry<T>(entity).State = EntityState.Added; 128 outEntity = entity; 129 return db.SaveChanges() > 0; 130 } 131 catch (Exception ex) 132 { 133 Log_DG(ex.ToString()); 134 outEntity = default(T); 135 return false; 136 } 137 } 138 public static Boolean IsAdd<T>(List<T> entities) where T : class 139 { 140 try 141 { 142 db.Set<T>().AddRange(entities); 143 return db.SaveChanges() > 0; 144 } 145 catch (Exception ex) 146 { 147 Log_DG(ex.ToString()); 148 return false; 149 } 150 } 151 152 #endregion 153 154 #region Update 155 156 public static Boolean IsUpdate<T>(T entity) where T : class 157 { 158 try 159 { 160 if (db.Entry<T>(entity).State == EntityState.Detached) 161 { 162 db.Set<T>().Attach(entity); 163 db.Entry<T>(entity).State = EntityState.Modified; 164 } 165 return db.SaveChanges() > 0; 166 } 167 catch (Exception ex) 168 { 169 Log_DG(ex.ToString()); 170 return false; 171 } 172 } 173 public static Boolean IsUpdate<T>(T entity, out T outEntity) where T : class 174 { 175 try 176 { 177 db.Set<T>().Attach(entity); 178 db.Entry<T>(entity).State = EntityState.Modified; 179 outEntity = entity; 180 return db.SaveChanges() > 0; 181 } 182 catch (Exception ex) 183 { 184 Log_DG(ex.ToString()); 185 outEntity = default(T); 186 return false; 187 } 188 } 189 190 #endregion 191 192 #region Delete 193 194 public static Boolean IsDelete<T>(T entity) where T : class 195 { 196 try 197 { 198 db.Set<T>().Attach(entity); 199 db.Entry<T>(entity).State = EntityState.Deleted; 200 return db.SaveChanges() > 0; 201 } 202 catch (Exception ex) 203 { 204 Log_DG(ex.ToString()); 205 return false; 206 } 207 } 208 public static Boolean IsDelete<T>(List<T> entities) where T : class 209 { 210 try 211 { 212 db.Set<T>().RemoveRange(entities); 213 return db.SaveChanges() > 0; 214 } 215 catch (Exception ex) 216 { 217 Log_DG(ex.ToString()); 218 return false; 219 } 220 } 221 public static Boolean IsDelete<T>(Expression<Func<T, bool>> deleteWhere) where T : class 222 { 223 try 224 { 225 List<T> entitys = db.Set<T>().AsExpandable().Where(deleteWhere).ToList(); 226 entitys.ForEach(m => db.Entry<T>(m).State = EntityState.Deleted); 227 return db.SaveChanges() > 0; 228 } 229 catch (Exception ex) 230 { 231 Log_DG(ex.ToString()); 232 return false; 233 } 234 } 235 #endregion 236 237 #region Select 238 239 public static Boolean IsExist<T>(Expression<Func<T, Boolean>> selectWhere) where T : class 240 { 241 try 242 { 243 return db.Set<T>().AsExpandable().Where(selectWhere).ToList().FirstOrDefault<T>() == null ? false : true; 244 } 245 catch (Exception ex) 246 { 247 Log_DG(ex.ToString()); 248 return default(Boolean); 249 } 250 } 251 public static T selectSingle<T>(Expression<Func<T, Boolean>> selectWhere) where T : class 252 { 253 try 254 { 255 return db.Set<T>().AsExpandable().Where(selectWhere).ToList().FirstOrDefault<T>(); 256 } 257 catch (Exception ex) 258 { 259 Log_DG(ex.ToString()); 260 return default(T); 261 } 262 } 263 public static List<T> selectAll<T>() where T : class 264 { 265 try 266 { 267 return db.Set<T>().AsExpandable().ToList(); 268 } 269 catch (Exception ex) 270 { 271 Log_DG(ex.ToString()); 272 return default(List<T>); 273 } 274 } 275 public static List<T> selectAll<T>(out int Count) where T : class 276 { 277 try 278 { 279 Count = db.Set<T>().AsExpandable().Count(); 280 return db.Set<T>().AsExpandable().ToList(); 281 } 282 catch (Exception ex) 283 { 284 Log_DG(ex.ToString()); 285 Count = 0; 286 return default(List<T>); 287 } 288 } 289 public static List<T> selectAll<T, TKey>(Expression<Func<T, TKey>> orderBy, Boolean isDESC = false) where T : class 290 { 291 try 292 { 293 if (isDESC) 294 return db.Set<T>().AsExpandable().OrderByDescending(orderBy).ToList(); 295 else 296 return db.Set<T>().AsExpandable().OrderBy(orderBy).ToList(); 297 } 298 catch (Exception ex) 299 { 300 Log_DG(ex.ToString()); 301 return default(List<T>); 302 } 303 } 304 public static List<T> selectAll<T, TKey>(Expression<Func<T, TKey>> orderBy, out int Count, Boolean isDESC = false) where T : class 305 { 306 try 307 { 308 Count = db.Set<T>().AsExpandable().Count(); 309 if (isDESC) 310 return db.Set<T>().AsExpandable().OrderByDescending(orderBy).ToList(); 311 else 312 return db.Set<T>().AsExpandable().OrderBy(orderBy).ToList(); 313 } 314 catch (Exception ex) 315 { 316 Log_DG(ex.ToString()); 317 Count = 0; 318 return default(List<T>); 319 } 320 } 321 public static List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere) where T : class 322 { 323 try 324 { 325 return db.Set<T>().AsExpandable().Where(selectWhere).ToList(); 326 } 327 catch (Exception ex) 328 { 329 Log_DG(ex.ToString()); 330 return default(List<T>); 331 } 332 } 333 public static List<T> selectAll<T>(Expression<Func<T, Boolean>> selectWhere, out int Count) where T : class 334 { 335 336 try 337 { 338 var list = db.Set<T>().AsExpandable().Where(selectWhere); 339 Count = list.Count(); 340 return list.ToList(); 341 } 342 catch (Exception ex) 343 { 344 Log_DG(ex.ToString()); 345 Count = 0; 346 return default(List<T>); 347 } 348 } 349 public static List<T> selectAll<T, TKey>(Expression<Func<T, TKey>> orderBy, Expression<Func<T, Boolean>> selectWhere, Boolean isDESC = false) where T : class 350 { 351 try 352 { 353 if (isDESC) 354 return db.Set<T>().AsExpandable().Where(selectWhere).OrderByDescending(orderBy).ToList(); 355 else 356 return db.Set<T>().AsExpandable().Where(selectWhere).OrderBy(orderBy).ToList(); 357 } 358 catch (Exception ex) 359 { 360 Log_DG(ex.ToString()); 361 return default(List<T>); 362 } 363 } 364 public static List<T> selectAll<T, TKey>(Expression<Func<T, TKey>> orderBy, Expression<Func<T, Boolean>> selectWhere, out int Count, Boolean isDESC = false) where T : class 365 { 366 try 367 { 368 var list = db.Set<T>().AsExpandable().Where(selectWhere); 369 Count = list.Count(); 370 if (isDESC) 371 return list.OrderByDescending(orderBy).ToList(); 372 else 373 return list.OrderBy(orderBy).ToList(); 374 } 375 catch (Exception ex) 376 { 377 Log_DG(ex.ToString()); 378 Count = 0; 379 return default(List<T>); 380 } 381 } 382 383 public static List<T> selectAllPaging<T, TKey>(int pageIndex, int pageSize, Expression<Func<T, TKey>> orderBy, Boolean isDESC = false) where T : class 384 { 385 try 386 { 387 var list = db.Set<T>().AsExpandable(); 388 if (isDESC) 389 return list.OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 390 else 391 return list.OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 392 } 393 catch (Exception ex) 394 { 395 Log_DG(ex.ToString()); 396 return default(List<T>); 397 } 398 } 399 public static List<T> selectAllPaging<T, TKey>(int pageIndex, int pageSize, Expression<Func<T, TKey>> orderBy, out int Count, Boolean isDESC = false) where T : class 400 { 401 try 402 { 403 var list = db.Set<T>().AsExpandable(); 404 Count = list.Count(); 405 if (isDESC) 406 return list.OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 407 else 408 return list.OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 409 } 410 catch (Exception ex) 411 { 412 Log_DG(ex.ToString()); 413 Count = 0; 414 return default(List<T>); 415 } 416 } 417 public static List<T> selectAllPaging<T, TKey>(int pageIndex, int pageSize, Expression<Func<T, TKey>> orderBy, Expression<Func<T, Boolean>> selectWhere, Boolean isDESC = false) where T : class 418 { 419 try 420 { 421 var list = db.Set<T>().AsExpandable().Where(selectWhere); 422 if (isDESC) 423 return list.OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 424 else 425 return list.OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 426 } 427 catch (Exception ex) 428 { 429 Log_DG(ex.ToString()); 430 return default(List<T>); 431 } 432 } 433 public static List<T> selectAllPaging<T, TKey>(int pageIndex, int pageSize, Expression<Func<T, TKey>> orderBy, Expression<Func<T, Boolean>> selectWhere, out int Count, Boolean isDESC = false) where T : class 434 { 435 try 436 { 437 var list = db.Set<T>().AsExpandable().Where(selectWhere); 438 Count = list.Count(); 439 if (isDESC) 440 return list.OrderByDescending(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 441 else 442 return list.OrderBy(orderBy).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); 443 } 444 catch (Exception ex) 445 { 446 Log_DG(ex.ToString()); 447 Count = 0; 448 return default(List<T>); 449 } 450 } 451 452 #endregion 453 } 454 }
这里说明一下：
1、IEF_DBEntity_DG 帮助类的接口，当然我没有继承这个接口，这个接口只是我以后回顾的时候看的，并没有实际使用价值，只作为说明性的文字，不喜勿碰哈。
2、采用单例模式，这里不做过多说明，单例的介绍铺天盖地，我只是说，使用的时候，需要在这里改动两处对应到实体关系类上。
3、使用泛型，泛型在帮助类的重要性不必多说了吧，写帮助类不用泛型...啧啧啧。
4、Log_DG 这里直接封装了EF操作的错误信息，一般在try catch中调用，对错误进行日志的描述，便于后续的错误查找。
5、里面分别封装了 增加、删除、修改、查询四种基础的操作，并且每种操作都附有大量的重载（尤其是查询）便于适应更多不断变化项目；还有一些是快捷的操作，IsExist 这里直接返回数据是否存在。
6、所有的条件采用lambda表达式的方式，lambda表达式是比较新颖比较方便的条件判断条件筛选方式之一，在未来会更多地使用lambda表达式进行操作，在C#6.0已然是得到了很大的支持。
7、恰到适宜的out 输出参数，保证了在需要插入并且需要插入的结果需求的使用。
8、查询的分页支持，不必再写繁琐的分页，这里已经对分页进行了支持。
具体内容，参考类详情吧，后续更新修改，敬请期待！ --柒小 2016年12月21日22:34:01
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