How can I prevent the LinqDataSource Where clause from resetting on postback?

问题

I'm trying to set the where clause on a LinqDataSource object bound to a GridView programmatically on a button click, but when the GridView rebinds data (for instance, when the user sorts) the Where clause resets back to the empty string. Is there a way to prevent this, or is there a better way to filter my results?

回答1:

Perhaps you just add a ViewState property into your page/user control and then retrieve it on all post back?

public string MyLinqSourceWhere 
{
    get { return (string)this.ViewState["MyLinqSourceWhere"]; }
    set { this.ViewState["MyLinqSourceWhere"] = value; }
}

public void Page_Load(object sender, EventArgs e) 
{
    this.myLinqSource.Where = this.MyLinqSourceWhere;
}

public void Button1_Click(object sender, EventArgs e) 
{
    this.MyLinqSourceWhere = " .... ";
    this.myLinqSource.Where = this.MyLinqSourceWhere;
}

If that doesn't work, then perhaps bind on the LinqDataSource.Selecting event the fetch property from the viewstate to your where clause?? It all depends

来源：https://stackoverflow.com/questions/2060004/how-can-i-prevent-the-linqdatasource-where-clause-from-resetting-on-postback