LINQ To SQL 拼接查询条件

private void DoQuery()
{
Expression<Func<DataAccess.e_Score_V, bool>> expr = n => GetCondition(n);
List<DataAccess.e_Score_V> lstScore = _Context.e_Score_V.Where(expr.Compile()).OrderByDescending(e => e.Score).Take(this.Records).ToList();
this.rptList.DataSource = lstScore;
this.rptList.DataBind();
}

private bool GetCondition(DataAccess.e_Score_V entiey)
{
bool result = true;

if (ValidationHelper.IsNumeric(this.txtUserID.Text))
{
result = entiey.UserID == int.Parse(this.txtUserID.Text);
}

if (!string.IsNullOrEmpty(this.dropScoreType.SelectedValue))
{
result &= entiey.ScoreType == int.Parse(this.dropScoreType.SelectedValue);
}

if (ValidationHelper.IsDateTime(this.txtFromDate.Text))
{
result &= entiey.ScoreDate >= DateTime.Parse(this.txtFromDate.Text);
}

if (ValidationHelper.IsDateTime(this.txtEndDate.Text))
{
result &= entiey.ScoreDate <= DateTime.Parse(this.txtEndDate.Text); ;
}

return result;
}