以下是我对EF DB FIRST 生成的ObjectContext类进行封装，代码如下，供参考学习：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Data.Objects.DataClasses;
6 using ZBService.Model;
7 using System.Linq.Expressions;
8
9 namespace ZBService
10 {
11 public abstract class ServiceBase<T> where T:EntityObject
12 {
13 protected mZhaoBiaoEntities zbEntities = new mZhaoBiaoEntities();
14
15 /// <summary>
16 /// 判断是否存在
17 /// </summary>
18 /// <param name="whereExpr"></param>
19 /// <returns></returns>
20 public bool Exist(Expression<Func<T,bool>> whereExpr)
21 {
22 return (this.Count(whereExpr) > 0);
23 }
24
25 /// <summary>
26 /// 获取记录数
27 /// </summary>
28 /// <param name="whereExpr"></param>
29 /// <returns></returns>
30 public int Count(Expression<Func<T, bool>> whereExpr)
31 {
32 return zbEntities.CreateObjectSet<T>().Where(whereExpr).Count();
33 }
34
35 /// <summary>
36 /// 查找实体对象
37 /// </summary>
38 /// <param name="whereExpr"></param>
39 /// <returns></returns>
40 public T Find(Expression<Func<T, bool>> whereExpr)
41 {
42 return zbEntities.CreateObjectSet<T>().Where(whereExpr).FirstOrDefault();
43 }
44
45 /// <summary>
46 /// 查找实体对象列表
47 /// </summary>
48 /// <param name="whereExpr"></param>
49 /// <returns></returns>
50 public IEnumerable<T> FindList<TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TKey>> orderbyExpr, int orderDirection)
51 {
52 return this.FindList<T, TKey>(whereExpr,t=>t,orderbyExpr,orderDirection);
53 }
54
55 /// <summary>
56 /// 查找实体对象列表
57 /// </summary>
58 /// <typeparam name="TResult"></typeparam>
59 /// <typeparam name="TKey"></typeparam>
60 /// <param name="whereExpr"></param>
61 /// <param name="selectExpr"></param>
62 /// <param name="orderbyExpr"></param>
63 /// <param name="orderDirection"></param>
64 /// <param name="returnCount"></param>
65 /// <returns></returns>
66 public IEnumerable<TResult> FindList<TResult,TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TResult>> selectExpr,Expression<Func<TResult,TKey>> orderbyExpr,int orderDirection,int returnCount=-1)
67 {
68 var result = zbEntities.CreateObjectSet<T>().Where(whereExpr).Select(selectExpr);
69 if (result != null && result.Count() > 0)
70 {
71 if (returnCount > 0)
72 {
73 if (orderDirection > 0)
74 {
75 result = result.OrderByDescending(orderbyExpr).Take(returnCount);
76 }
77 else
78 {
79 result = result.OrderBy(orderbyExpr).Take(returnCount);
80 }
81 }
82 return result.ToList();
83 }
84 return null;
85 }
86
87 /// <summary>
88 /// 分页查找实体对象列表
89 /// </summary>
90 /// <typeparam name="TResult"></typeparam>
91 /// <typeparam name="TKey"></typeparam>
92 /// <param name="whereExpr"></param>
93 /// <param name="selectExpr"></param>
94 /// <param name="orderbyExpr"></param>
95 /// <param name="orderDirection"></param>
96 /// <param name="pageSize"></param>
97 /// <param name="pageNo"></param>
98 /// <param name="recordCount"></param>
99 /// <returns></returns>
100 public IEnumerable<TResult> FindListByPage<TResult,TKey>(Expression<Func<T, bool>> whereExpr, Expression<Func<T, TResult>> selectExpr,Expression<Func<TResult,TKey>> orderbyExpr,int orderDirection,int pageSize,int pageNo,out int recordCount)
101 {
102 var result = zbEntities.CreateObjectSet<T>().Where(whereExpr).Select(selectExpr);
103 recordCount = result.Count();
104
105 if(pageNo>recordCount) pageNo=recordCount;
106 if(pageNo<=0) pageNo=1;
107
108 if (recordCount > 0)
109 {
110 if (recordCount > pageSize)
111 {
112 if (orderDirection > 0)
113 {
114 return result.OrderByDescending(orderbyExpr).Skip((pageNo - 1) * pageSize).Take(pageSize).ToList();
115 }
116 else
117 {
118 return result.OrderBy(orderbyExpr).Skip((pageNo - 1) * pageSize).Take(pageSize).ToList();
119 }
120 }
121 else
122 {
123 if (orderDirection > 0)
124 {
125 return result.OrderByDescending(orderbyExpr).ToList();
126 }
127 else
128 {
129 return result.OrderBy(orderbyExpr).ToList();
130 }
131 }
132
133 }
134 return null;
135 }
136
137
138
139
140 /// <summary>
141 /// 增加实体
142 /// </summary>
143 /// <param name="entity"></param>
144 public virtual void Add(T entity)
145 {
146 this.ValidateEntity(entity,ValidateMode.Add);
147 zbEntities.CreateObjectSet<T>().AddObject(entity);
148 }
149
150
151 /// <summary>
152 /// 增加实体列表
153 /// </summary>
154 /// <param name="entities"></param>
155 public virtual void AddList(IEnumerable<T> entities)
156 {
157 var objSet = zbEntities.CreateObjectSet<T>();
158 foreach (T entity in entities)
159 {
160 this.ValidateEntity(entity, ValidateMode.Add);
161 objSet.AddObject(entity);
162 }
163 }
164
165 /// <summary>
166 /// 更新已分离实体,若未分离则不需要执行该方法
167 /// </summary>
168 /// <param name="entity"></param>
169 public virtual void Update(T entity)
170 {
171 this.ValidateEntity(entity, ValidateMode.Update);
172 zbEntities.CreateObjectSet<T>().ApplyCurrentValues(entity);
173 }
174
175 /// <summary>
176 /// 删除实体
177 /// </summary>
178 /// <param name="entity"></param>
179 public virtual void Delete(T entity)
180 {
181 this.ValidateEntity(entity, ValidateMode.Delete);
182 zbEntities.CreateObjectSet<T>().DeleteObject(entity);
183 }
184
185 /// <summary>
186 /// 删除实体
187 /// </summary>
188 /// <param name="whereExpr"></param>
189 public virtual void Delete(Expression<Func<T, bool>> whereExpr)
190 {
191 var objSet = zbEntities.CreateObjectSet<T>();
192 T entity = objSet.Where(whereExpr).Single();
193 //this.ValidateEntity(entity, ValidateMode.Delete);
194 objSet.DeleteObject(entity);
195 }
196
197 /// <summary>
198 /// 删除实体列表
199 /// </summary>
200 /// <param name="entities"></param>
201 public virtual void DeleteList(IEnumerable<T> entities)
202 {
203 var objSet = zbEntities.CreateObjectSet<T>();
204 foreach (T entity in entities)
205 {
206 //this.ValidateEntity(entity, ValidateMode.Delete);
207 objSet.DeleteObject(entity);
208 }
209 }
210
211
212 /// <summary>
213 /// 提交保存所有变更操作
214 /// </summary>
215 public void SubmitSave()
216 {
217 zbEntities.SaveChanges();
218 }
219
220
221 /// <summary>
222 /// 验证
223 /// </summary>
224 /// <param name="entity"></param>
225 /// <returns></returns>
226 protected virtual void ValidateEntity(T entity,ValidateMode mode=ValidateMode.Add)
227 {
228
229 }
230
231 /// <summary>
232 /// 验证模式
233 /// </summary>
234 protected enum ValidateMode
235 {
236 Add=0,
237 Update=1,
238 Delete=-1
239 }
240
241 }
242 }
之所以声明为abstract,要求子类必需继承后才能正常使用，这里面有一个ValidateEntity方法，主用于子类在RUD前，验证实体对象数据完整性，可重写也可不重写！
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时间： 2024-10-12 03:02:28