EF架构~过滤导航属性等，拼接SQL字符串
拼接Ｔ—ＳＱＬ串，并使它具有通用性
好处：与服务器建立一次连接，给服务器发一条ＳＱＬ命令，即可实现
代码如下：
1 /// <summary>
2 /// 构建Insert语句串
3 /// 主键为自增时，如果主键值为0，我们将主键插入到SQL串中
4 /// </summary>
5 /// <typeparam name="TEntity"></typeparam>
6 /// <param name="entity"></param>
7 /// <returns></returns>
8 private Tuple<string, object[]> CreateInsertSQL<TEntity>(TEntity entity) where TEntity : class
9 {
10 if (entity == null)
11 throw new ArgumentException("The database entity can not be null.");
12
13 Type entityType = entity.GetType();
14 var table = entityType.GetProperties().Where(i => i.PropertyType != typeof(EntityKey)
15 && i.PropertyType != typeof(EntityState)
16 && i.GetValue(entity, null) != null
17 && (i.PropertyType.IsValueType || i.PropertyType == typeof(string)))
18 .ToArray();//过滤主键，航行属性，状态属性等
19 List<string> pkList = GetPrimaryKey<TEntity>().Select(i => i.Name).ToList();
20
21 List<object> arguments = new List<object>();
22 StringBuilder fieldbuilder = new StringBuilder();
23 StringBuilder valuebuilder = new StringBuilder();
24
25 fieldbuilder.Append(" INSERT INTO " + string.Format("[{0}]", entityType.Name) + " (");
26
27 foreach (var member in table)
28 {
29 if (pkList.Contains(member.Name) && Convert.ToString(member.GetValue(entity, null)) == "0")
30 continue;
31 object value = member.GetValue(entity, null);
32 if (value != null)
33 {
34 if (arguments.Count != 0)
35 {
36 fieldbuilder.Append(", ");
37 valuebuilder.Append(", ");
38 }
39
40 fieldbuilder.Append(member.Name);
41 if (member.PropertyType == typeof(string) || member.PropertyType == typeof(DateTime))
42 valuebuilder.Append("'{" + arguments.Count + "}'");
43 else
44 valuebuilder.Append("{" + arguments.Count + "}");
45 if (value.GetType() == typeof(string))
46 value = value.ToString().Replace("'", "char(39)");
47 arguments.Add(value);
48
49 }
50 }
51
52
53 fieldbuilder.Append(") Values (");
54
55 fieldbuilder.Append(valuebuilder.ToString());
56 fieldbuilder.Append(");");
57 return new Tuple<string, object[]>(fieldbuilder.ToString(), arguments.ToArray());
58 }
对于EF架构中的批量更新操作，需要我们为实体的导航属性进行手动的标示，因为EF生成的实体中没有一个特殊的说明，所以，我们必须要告诉系统，哪个属性是导航属性，而导航属性是我们不去进行update的。
1 /// <summary>
2 /// 属性的导航属性
3 /// </summary>
4 public class NavigationAttribute : Attribute
5 {
6
7 }
而对于要进行批量更新的实体，我们需要为导航属性添加这个特性
1 public class User
2 {
3 public int UserID { get; set; }
4 [Navigation]
5 public User_Extension User_Extension { get; set; }
6 }
而对于我们构建批量Update语句，请看代码，它需要对导航属性进行过滤
1 /// <summary>
2 /// 构建Update语句串
3 /// </summary>
4 /// <typeparam name="TEntity"></typeparam>
5 /// <param name="entity"></param>
6 /// <returns></returns>
7 private Tuple<string, object[]> CreateUpdateSQL<TEntity>(TEntity entity) where TEntity : class
8 {
9 if (entity == null)
10 throw new ArgumentException("The database entity can not be null.");
11 List<string> pkList = GetPrimaryKey<TEntity>().Select(i => i.Name).ToList();
12
13 Type entityType = entity.GetType();
14 var table = entityType.GetProperties().Where(i =>
15 !pkList.Contains(i.Name)
16 && i.GetValue(entity, null) != null
17 && i.PropertyType != typeof(EntityState)
18 && !(i.GetCustomAttributes(false).Length > 0
19 && i.GetCustomAttributes(false).Where(j => j.GetType() == typeof(NavigationAttribute)) != null)
20 && (i.PropertyType.IsValueType || i.PropertyType == typeof(string)) //过滤导航属性
21 ).ToArray();
22
23 //过滤主键，航行属性，状态属性等
24 if (pkList == null || pkList.Count == 0)
25 throw new ArgumentException("The Table entity have not a primary key.");
26 List<object> arguments = new List<object>();
27 StringBuilder builder = new StringBuilder();
28
29 foreach (var change in table)
30 {
31 if (pkList.Contains(change.Name))
32 continue;
33 if (arguments.Count != 0)
34 builder.Append(", ");
35 builder.Append(change.Name + " = {" + arguments.Count + "}");
36 if (change.PropertyType == typeof(string) || change.PropertyType == typeof(DateTime))
37 arguments.Add("'" + change.GetValue(entity, null).ToString().Replace("'", "char(39)") + "'");
38 else
39 arguments.Add(change.GetValue(entity, null));
40 }
41
42 if (builder.Length == 0)
43 throw new Exception("没有任何属性进行更新");
44
45 builder.Insert(0, " UPDATE " + string.Format("[{0}]", entityType.Name) + " SET ");
46
47 builder.Append(" WHERE ");
48 bool firstPrimaryKey = true;
49
50 foreach (var primaryField in pkList)
51 {
52 if (firstPrimaryKey)
53 firstPrimaryKey = false;
54 else
55 builder.Append(" AND ");
56
57 object val = entityType.GetProperty(primaryField).GetValue(entity, null);
58 builder.Append(GetEqualStatment(primaryField, arguments.Count));
59 arguments.Add(val);
60 }
61 return new Tuple<string, object[]>(builder.ToString(), arguments.ToArray());
62
63 }
而对子类公开的Update方法，我们进行了一个封装，它通过操作枚举来确实你是要insert,update还是delete，看代码
1 /// <summary>
2 /// 执行ＳＱＬ，根据ＳＱＬ操作的类型
3 /// </summary>
4 /// <typeparam name="TEntity"></typeparam>
5 /// <param name="list"></param>
6 /// <param name="sqlType"></param>
7 /// <returns></returns>
8 protected string DoSQL<TEntity>(IEnumerable<TEntity> list, SQLType sqlType) where TEntity : class
9 {
10 StringBuilder sqlstr = new StringBuilder();
11 switch (sqlType)
12 {
13 case SQLType.Insert:
14 list.ToList().ForEach(i =>
15 {
16 Tuple<string, object[]> sql = CreateInsertSQL(i);
17 sqlstr.AppendFormat(sql.Item1, sql.Item2);
18 });
19 break;
20 case SQLType.Update:
21 list.ToList().ForEach(i =>
22 {
23 Tuple<string, object[]> sql = CreateUpdateSQL(i);
24 sqlstr.AppendFormat(sql.Item1, sql.Item2);
25 });
26 break;
27 case SQLType.Delete:
28 list.ToList().ForEach(i =>
29 {
30 Tuple<string, object[]> sql = CreateDeleteSQL(i);
31 sqlstr.AppendFormat(sql.Item1, sql.Item2);
32 });
33 break;
34 default:
35 throw new ArgumentException("请输入正确的参数");
36 }
37 return sqlstr.ToString();
38 }
出处：http://www.cnblogs.com/lori/ 欢迎转载
