c# lamuda 表達(dá)式拼接
發(fā)布日期:2022/8/31 作者:
瀏覽:1096
public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2)
{
var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>(Expression.Or(expression1.Body, invokedExpression), expression1.Parameters);
}
public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expression1, Expression<Func<T, bool>> expression2)
{
var invokedExpression = Expression.Invoke(expression2, expression1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>(Expression.And(expression1.Body, invokedExpression), expression1.Parameters);
}
用法:
List<EasyuiFilter> filter = Newtonsoft.Json.JsonConvert.DeserializeObject<List<EasyuiFilter>>(filterRules);
Expression<Func<WebError, bool>> lmd = c => c.ID != 0;
if (filter.Any(c => c.Field == "Code"))
{
EasyuiFilter item = filter.Where(f => f.Field == "Code").FirstOrDefault();
if (item.Op == "equal")
{
lmd = lmd.And(c => c.Code == Convert.ToInt32(item.Value));
}
else
{
lmd = lmd.And(c => c.Code != Convert.ToInt32(item.Value));
}
}
if (filter.Any(c => c.Field == "IP"))
{
EasyuiFilter item = filter.Where(f => f.Field == "IP").FirstOrDefault();
if (item.Op == "equal")
{
lmd = lmd.And(c => c.IP == item.Value);
}
else
{
lmd = lmd.And(c => c.IP != item.Value);
}
}
//使用lamada變量 _context.WebErrors.Where(lmd).Count()
下拉加載更多評(píng)論