C# 常用工具方法之DataTable（一）
程序员文章站
2022-06-10 19:32:09
1、DataTable 转 泛型T的List 2、DataTable 转 HashTable 3、DataTable 转 HashTable 4、DataTable 按照某列进行条件拆分 日常工作常遇到的utils中积累的代码，可以优化的地方希望多多指教！ ......
1、datatable 转 泛型t的list
/// <summary>
/// 数据集datatable转换成list集合
/// </summary>
/// <typeparam name="t"></typeparam>
/// <param name="dttemp"></param>
/// <returns></returns>
public static list<t> tolistbydatatable<t>(datatable dttemp)
{
if (dttemp == null || dttemp.rows.count == 0)
{
return null;
}
list<t> lstresult = new list<t>();
for (int j = 0, l = dttemp.rows.count; j < l; j++)
{
t _t = (t)activator.createinstance(typeof(t));
propertyinfo[] propertys = _t.gettype().getproperties();
foreach (propertyinfo pi in propertys)
{
for (int i = 0, k = dttemp.columns.count; i < k; i++)
{
// 属性与字段名称一致的进行赋值
if (pi.name.tolower().equals(dttemp.columns[i].columnname.tolower()))
{
if (dttemp.rows[j][i] != dbnull.value)
{
switch (pi.propertytype.tostring())
{
case "system.int32":
pi.setvalue(_t, nall.toint(dttemp.rows[j][i].tostring()), null);
break;
case "system.int64":
pi.setvalue(_t, nall.tolong(dttemp.rows[j][i].tostring()), null);
break;
case "system.datetime":
pi.setvalue(_t, nall.todatetime(dttemp.rows[j][i].tostring()), null);
break;
case "system.string":
pi.setvalue(_t, dttemp.rows[j][i].tostring(), null);
break;
case "system.boolean":
pi.setvalue(_t, nall.toboolean(dttemp.rows[j][i].tostring()), null);
break;
case "system.guid":
pi.setvalue(_t, nall.toguid(dttemp.rows[j][i].tostring()), null);
break;
case "system.single":
pi.setvalue(_t, convert.tosingle(dttemp.rows[j][i].tostring()), null);
break;
case "system.double":
pi.setvalue(_t, convert.todouble(dttemp.rows[j][i].tostring()), null);
break;
case "system.object":
pi.setvalue(_t, dttemp.rows[j][i], null);
break;
}
}
else
{
switch (pi.propertytype.tostring())
{
case "system.int32":
pi.setvalue(_t, -1, null);
break;
case "system.int64":
pi.setvalue(_t, -1, null);
break;
case "system.datetime":
pi.setvalue(_t, new datetime(0x76c, 1, 1), null);
break;
case "system.boolean":
pi.setvalue(_t, false, null);
break;
case "system.guid":
pi.setvalue(_t, guid.empty, null);
break;
case "system.single":
pi.setvalue(_t, 0.0f, null);
break;
case "system.double":
pi.setvalue(_t, 0.0, null);
break;
case "system.string":
pi.setvalue(_t, string.empty, null);
break;
default:
pi.setvalue(_t, null, null);
break;
}
}
break;
}
}
}
lstresult.add(_t);
}
return lstresult;
}
2、datatable 转 hashtable
/// <summary>
/// datatable转hashtable
/// </summary>
/// <param name="dt"></param>
/// <param name="key"></param>
/// <returns></returns>
public static hashtable tohashtablebydatarow(datatable dt, int key)
{
hashtable ht = new hashtable();
for (int i = 0; i < dt.columns.count; i++)
{
ht.add(dt.columns[i].columnname, dt.rows[key][i]);
}
return ht;
}
3、datatable 转 hashtable
/// <summary>
/// 转换哈希表
/// </summary>
/// <typeparam name="t"></typeparam>
/// <param name="dt"></param>
/// <returns></returns>
public static list<hashtable> tohashtablebydatatable<t>(datatable dt)
{
list<hashtable> listht = new list<hashtable>();
for (int i = 0; i < dt.rows.count; i++)
{
hashtable ht = new hashtable();
ht.add(i, dt.rows[i]);
listht.add(ht);
}
return listht;
}
4、datatable 按照某列进行条件拆分
/// <summary>
/// 拆分dt，返回相同数据结构的多个dt
/// [excel需要去掉第一行标题]
/// </summary>
/// <param name="dt">原始数据dt</param>
/// <param name="condition">第几列数据，按照这一列进行拆分</param>
/// <param name="orderstr">排序条件，dataview的排序条件</param>
/// <returns></returns>
public static list<datatable> splitdtsamestruct(datatable dt,int columnnum,string orderstr) {
//定义返回对象
list<datatable> listdt = new list<datatable>();
//按照条件进行筛选
list<string> conditionstr = new list<string>();
foreach (datarow dr in dt.rows)
{
//筛选字段的值
string key = dr["column"+ columnnum].tostring();
//不存在新增进条件conditionstr中
if (!isexit(conditionstr,key)) {
conditionstr.add(key);
}
}
//根据条件conditionstr集合进行拆分dt
//1、将dt数据源按照字段排序
dt.columns.add();
dataview view = new dataview(dt);
//正序排列
view.sort = orderstr;//"column"+ columnnum + " asc";
dt = view.totable();
foreach (string str in conditionstr)
{
//按照条件进行抽取数据
datarow[] dr = dt.select("column"+ columnnum + "='"+str+"'");
//抽出的数据存入临时的tempdt中
datatable tempdt = new datatable();
tempdt = dt.clone();//拷贝框架
for (int i = 0; i < dr.length; i++)
{
tempdt.importrow((datarow)dr[i]);
}
//tempdt存入返回对象listdt中
listdt.add(tempdt);
}
return listdt;
}
日常工作常遇到的utils中积累的代码，可以优化的地方希望多多指教！