原创最简单的ORM例子
这个仅是为了培训做的一个小例子
public class DB {
public static string GetClassName(Type type)
{
if (type == null)
throw new ArgumentException("参数type不能为空");
else{
if (type.HasAttribute<DBTableNameAttribute>())
return type.GetAttribute<DBTableNameAttribute>().Name;
else
return type.Name;
}
}
public static T AddObject<T>(T o) where T :class
{
string tablename = GetClassName(typeof(T));
string fieldName;
object fieldValue;
string[] fieldNames;
object[] fieldValues;
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
fieldNames=new string[Props.Length ];
fieldValues =new object [Props.Length ];
string checkstr = "";
for (int i = 0; i < Props.Length; i++)
{
fieldName = Props[i].Name;
fieldValue = Props[i].GetValue(o, null);
if (fieldValue == null) continue;
fieldValue = CommonFunction.SafeSQL(fieldValue.ToString());
fieldNames[i] = fieldName;
fieldValues[i] = fieldValue;
object[] attributes = Props[i].GetCustomAttributes(false);
foreach (Attribute a in attributes)
{
//判断Attribute 中是否 为 UniqueColumnAttribute
if (a is UniqueColumnAttribute)
{
checkstr = "not exists(select * from " +tablename + " where " + fieldName + "='" + fieldValue + "')";
}
}
}
if (checkstr != "")
{
checkstr = "if("+checkstr +")";
}
string insert = "" ,tail="";
insert = "insert into " + tablename + " (";
tail = "values(";
for (int i = 0; i < Props.Length; i++)
{
fieldName = fieldNames[i] ;
if (fieldName.ToUpper() == "ID") continue;
object _fieldValue = fieldValues[i];
if (_fieldValue == null)
{ }
else
{
insert += fieldName + ",";
tail += "'" + _fieldValue + "',";
}
}
insert = insert.Remove(insert.Length - 1);
tail = tail.Remove(tail.Length - 1);
string insertstr = insert + ")" + " " + tail + ")";
if (checkstr != "")
insertstr = checkstr +"begin "+ insertstr+" end";
insertstr+=" select @@identity"
SqlHelper link = new SqlHelper();
int r= link.UpdateDataBase(insertstr);
if(r>0) {
o.Id=r;
return o;
}
return null;
}
public static bool DelObject<T>( int id) where T : class
{
if (id == 0) return false;
string tablename = GetClassName(typeof(T));
string insert = "";
insert =string.Format( "delete from {0} where id={1}",tablename,id)
SqlHelper link = new SqlHelper();
int r = link.UpdateDataBase(insert);
return true;
}
public static bool DelObject<T>(T o) where T : class
{
string tablename = GetClassName(typeof(T));
string fieldName;
object fieldValue;
string[] fieldNames;
object[] fieldValues;
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
fieldNames = new string[Props.Length];
fieldValues = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
fieldName = Props[i].Name;
fieldValue = Props[i].GetValue(o, null);
fieldNames[i] = fieldName;
fieldValues[i] = fieldValue;
}
string str="";
for (int i = 0; i < Props.Length; i++)
{
fieldName = fieldNames[i];
string _fieldValue = fieldValues[i].ToString();
if (fieldName.ToUpper() == "ID")
{
str = "delete from " + tablename + " where id=" + _fieldValue ;
break;
}
}
if(!string.IsNullOrEmpty(str))
{
SqlHelper link = new SqlHelper();
int r = link.UpdateDataBase(str);
return true;
}
return false;
}
public static bool UpdateObject<T>(T o) where T : class
{
string tablename = GetClassName(typeof(T));
string fieldName;
object fieldValue;
string[] fieldNames;
object[] fieldValues;
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
fieldNames = new string[Props.Length];
fieldValues = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
if (Props[i].DeclaringType.IsValueType)
{
fieldName = Props[i].Name;
fieldValue = Props[i].GetValue(o, null);
fieldNames[i] = fieldName;
fieldValues[i] = fieldValue;
}
else
{
fieldNames[i] = null;
fieldValues[i] = null;
}
}
string str = "update "+tablename +" set ",where=" where id=";
int id = 0;
for (int i = 0; i < Props.Length; i++)
{
fieldName = fieldNames[i];
object _fieldValue = fieldValues[i] ;
if (fieldName == null) continue;
if (fieldName.ToUpper() == "ID")
{
if (_fieldValue == null)
{
}
else
{
int.TryParse(_fieldValue.ToString(), out id);
//str = "delete from " + tablename + " where id=" + _fieldValue;
where += id.ToString();
}
//break;
}
else
{
if (_fieldValue == null)
{
}
else
str += fieldName + "='" + _fieldValue.ToString() + "',";
}
}
if (id <= 0) return false;
str = str.Remove(str.Length - 1);
str += where;
SqlHelper link = new SqlHelper();
int r = link.UpdateDataBase(str);
return true;
}
public static T SelObject<T>(int id) where T : class
{
if (id <= 0) return null ;
string tablename = GetClassName(typeof(T));
string insert = "";
insert = "select * from " + tablename + " where id=" + id.ToString();
SqlHelper link = new SqlHelper();
DataTable dt = link.SelectDataBase(insert);
if (dt == null || dt.Rows.Count == 0) return null;
Type type = typeof(T);
Object obj = type.Assembly.CreateInstance(type.FullName);
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
for (int i = 0; i < Props.Length; i++)
{
Props[i].SetValue(obj, dt.Rows[0][Props[i].Name], null);
}
return (T)obj;
}
public static T SelObject<T>(BaseQuery query ) where T : class
{
if (query==null )
return null;
string tablename = GetClassName(typeof(T));
if (tablename.EndsWith("Query"))
tablename = tablename.Replace("Query","");
string fieldName;
object fieldValue;
string[] fieldNames;
object[] fieldValues;
System.Reflection.PropertyInfo[] Props = query.GetType().GetProperties();
fieldNames = new string[Props.Length];
fieldValues = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
fieldName = Props[i].Name;
fieldValue = Props[i].GetValue(query, null);
fieldNames[i] = fieldName;
fieldValues[i] = fieldValue;
}
string insert = "",where="1=1";
insert = "select * from " + tablename + " where " ;
int id = 0;
for (int i = 0; i < Props.Length; i++)
{
fieldName = fieldNames[i];
object _fieldValue = fieldValues[i];
if (fieldName.ToUpper() == "ID")
{
if (_fieldValue == null)
{ }
else
{
int.TryParse(_fieldValue.ToString(), out id);
//str = "delete from " + tablename + " where id=" + _fieldValue;
where +="Id="+ id.ToString();
}
//break;
}
else
{
if (_fieldValue == null)
{ }
else
{
if (string.IsNullOrEmpty(_fieldValue.ToString()))
{ }
else
where += " and " + fieldName + "='" + _fieldValue.ToString() + "'";
}
}
}
insert = insert + where;
SqlHelper link = new SqlHelper();
DataTable dt = link.SelectDataBase(insert);
if (dt == null || dt.Rows.Count == 0) return null;
Type type = typeof(T);
Object obj = type.Assembly.CreateInstance(type.FullName );
System.Reflection.PropertyInfo[] Props2 = typeof(T).GetProperties();
for (int i = 0; i < Props2.Length; i++)
{
Props2[i].SetValue(obj, dt.Rows[0][Props2[i].Name], null);
}
return (T)obj;
}
public static T SelObject<T>(string where) where T : class
{
if (string.IsNullOrEmpty(where)) ) return null;
string tablename = GetClassName(typeof(T));
string insert = "";
insert = "select * from " + tablename + " where " + where;
SqlHelper link = new SqlHelper();
DataTable dt = link.SelectDataBase(insert);
if (dt == null || dt.Rows.Count == 0) return null;
Type type = typeof(T);
Object obj = type.Assembly.CreateInstance(type.FullName);
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
for (int i = 0; i < Props.Length; i++)
{
Props[i].SetValue(obj, dt.Rows[0][Props[i].Name], null);
}
return (T)obj;
}
public static List<T> ListObjects<T>(string where) where T : class
{
try
{
if (string.IsNullOrEmpty(where))
where = "1=1";
string tablename = GetClassName(typeof(T));
string insert = "";
insert = "select * from " + tablename + " where " + where;
SqlHelper link = new SqlHelper();
DataTable dt = link.SelectDataBase(insert);
if (dt == null || dt.Rows.Count == 0) return null;
Type type = typeof(T);
List<T> list = new List<T>();
for (int row = 0; row < dt.Rows.Count; row++)
{
Object obj = type.Assembly.CreateInstance(type.FullName );
System.Reflection.PropertyInfo[] Props = typeof(T).GetProperties();
for (int i = 0; i < Props.Length; i++)
{
Props[i].SetValue(obj, dt.Rows[row][Props[i].Name], null);
}
list.Add((T)obj);
}
return list;
}
catch
{
return null;
}
}
}
