/// <summary>
/// 按条件删除数据
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="where">linq</param>
/// <returns>删除行数</returns>
public static int Delete <T>(Expression <Func <T, bool> > where) where T : class
{
try
{
if (where == null)
{
throw new ArgumentNullException();
}
int rows = 0;
using (var db = new DemoEntities())
{
var list = db.Set <T>().Where(where).ToList();
foreach (var item in list)
{
db.Set <T>().Remove(item);
rows += db.SaveChanges();
}
}
return(rows);
}
catch (Exception ex)
{
WriteException(ex);
return(0);
}
}
/// <summary>
/// 更新指定字段
/// </summary>
/// <param name="model">实体</param>
/// <param name="fileds">更新字段数组</param>
public static int Update <T>(T model, params string[] fileds) where T : class
{
try
{
if (model == null || fileds == null)
{
return(0);
}
using (var db = new DemoEntities())
{
db.Set <T>().Attach(model);
var SetEntry = ((IObjectContextAdapter)db).ObjectContext.ObjectStateManager.GetObjectStateEntry(model);
foreach (var filed in fileds)
{
SetEntry.SetModifiedProperty(filed);
}
return(db.SaveChanges());
}
}
catch (Exception ex)
{
WriteException(ex);
return(0);
}
}
/// <summary>
/// 根据条件分页查询
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="page">页码</param>
/// <param name="size">页面大小</param>
/// <param name="where">linq表达式</param>
/// <returns></returns>
public static DataGrid <T> SelectPage <T, TKey>(int page, int size, Expression <Func <T, TKey> > orderby, Expression <Func <T, bool> > where = null) where T : class
{
try
{
where = where ?? (p => true);
var total = Count(where);
if (total <= 0)
{
return new DataGrid <T>()
{
total = 0, rows = new List <T>(), emptyMsg = "没有查询到相关数据"
}
}
;
DataGrid <T> grid = new DataGrid <T>();
grid.total = total;
grid.emptyMsg = "查询成功";
using (var db = new DemoEntities())
{
grid.rows = db.Set <T>().Where(where).OrderBy(orderby).Skip((page - 1) * size).Take(size).ToList();
}
return(grid);
}
catch (Exception ex)
{
WriteException(ex);
return(new DataGrid <T>()
{
total = 0, rows = new List <T>(), emptyMsg = "查询故障，请联系开发人员"
});
}
}
/// <summary>
/// 根据条件查询数据量，返回-1表示错误
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="where">linq表达式</param>
public static int Count <T>(Expression <Func <T, bool> > where) where T : class
{
try
{
where = where ?? (p => true);
using (var db = new DemoEntities())
{
return(db.Set <T>().Count(where));
}
}
catch (Exception ex)
{
WriteException(ex);
return(-1);
}
}
/// <summary>
/// 根据条件查询数据
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="where">linq表达式</param>
public static IList <T> Select <T>(Expression <Func <T, bool> > where = null) where T : class
{
try
{
where = where ?? (p => true);
using (var db = new DemoEntities())
{
return(db.Set <T>().Where(where).ToList());
}
}
catch (Exception ex)
{
WriteException(ex);
return(new List <T>());
}
}
/// <summary>
/// 新增多条数据
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="models">多条模型数据</param>
public static int InsertList <T>(IEnumerable <T> models) where T : class
{
try
{
int rows = 0;
using (var db = new DemoEntities())
{
db.Set <T>().AddRange(models);
rows += db.SaveChanges();
}
return(rows);
}
catch (Exception ex)
{
WriteException(ex);
return(0);
}
}
/// <summary>
/// 更新单条数据
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="model">模型数据</param>
public static int Update <T>(T model) where T : class
{
try
{
int rows = 0;
using (var db = new DemoEntities())
{
if (db.Entry(model).State == EntityState.Detached)
{
db.Set <T>().Attach(model);
db.Entry(model).State = EntityState.Modified;
}
rows += db.SaveChanges();
}
return(rows);
}
catch (Exception ex)
{
WriteException(ex);
return(0);
}
}
/// <summary>
/// 使用查询条件更新数据
/// </summary>
/// <typeparam name="T">表的实体类</typeparam>
/// <param name="action">更新数据动作</param>
/// <param name="where">表达式</param>
public static int Update <T>(Action <T> action, Expression <Func <T, bool> > where) where T : class
{
try
{
int rows = 0;
using (var db = new DemoEntities())
{
var list = db.Set <T>().Where(where);
foreach (var model in list)
{
action.Invoke(model);
db.Entry(model).State = EntityState.Modified;
}
rows += db.SaveChanges();
}
return(0);
}
catch (Exception ex)
{
WriteException(ex);
return(0);
}
}
