Scenario:
User submits search criteria and selects an item from search results on the same page, which navigates to a new page of details for the selected item.
When the User returns to the search screen, the search criteria & results (including selected page and sort-order) should be preserved from their last visit.
Related information:
Thoughts:
I've read a lot of suggested methods for addressing various parts of this scenario, but I'm still confused; no comprehensively "correct" solution jumps to the forefront.
I guess I'm asking for recommendations/approach rather than a whole solution spelled out for me (although that would be nice! ;-)
The .NET VIEWSTATE would seem to do exactly what I'm after (with the exception of #5) - Is there some way of leveraging off this so that viewstate can be used between pages, and not just between postbacks to the same page? (e.g. can I store/restore viewstate to/from a session variable or something? I haven't seen this suggested anywhere and I'm wondering if there's a reason why.)
Thanks in advance.
Thanks for all the advice.
For the benefit of others, here is a solution to this issue (no doubt there's room for improvement, but this works satisfactorily for the moment).
4 functions...
StoreSearchCookie - Persist the state/values of a panel of search criteria and a results grid in a cookie with a specified UID.
RestoreSearchCookie_Criteria - Read the cookie and re-populate the search criteira
RestoreSearchCookie_Results - Read the cookie and restore the grid state.
FindFormControls - Helper method to recursively find form-input controls in a container (pinched & modified from elsewhere on Stack Overflow)
NB...
GridSettingsPersister.cs available from Telerik website, (but I had to modify it to store the page number as well)Usage is as follows...
protected void Page_PreRender(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
// Store the state of the page
StoreSearchCookie("SomeSearchPage", pnlSearchCriteria, gridResults);
}
else
{
// Restore search criteria
RestoreSearchCookie_Criteria("SomeSearchPage");
// Re-invoke the search here
DoSearch(); // (for example)
// Restore the grid state
RestoreSearchCookie_Results("SomeSearchPage");
}
}
Code follows...
protected void StoreSearchCookie(string cookieName, Panel SearchPanel, RadGrid ResultsGrid)
{
try
{
HttpCookie cookieCriteria = new HttpCookie("StoredSearchCriteria_" + cookieName);
// 1. Store the search criteria
//
List<Control> controls = new List<Control>();
FindFormControls(controls, SearchPanel);
foreach (Control control in controls)
{
string id = control.ID;
string parentId = control.Parent.ID;
string uid = string.Format("{0}>{1}", parentId, id);
string value = "";
Type type = control.GetType();
bool isValidType = true; // Optimistic!
if (type == typeof(TextBox))
{
value = ((TextBox)control).Text;
}
else if (type == typeof(DropDownList))
{
value = ((DropDownList)control).SelectedValue;
}
else if (type == typeof(HiddenField))
{
value = ((HiddenField)control).Value;
}
else if (type == typeof(RadioButton))
{
value = ((RadioButton)control).Checked.ToString();
}
else if (type == typeof(CheckBox))
{
value = ((CheckBox)control).Checked.ToString();
}
else
{
isValidType = false;
}
if (isValidType)
{
cookieCriteria.Values[uid] = value;
}
}
cookieCriteria.Expires = DateTime.Now.AddDays(1d);
Response.Cookies.Add(cookieCriteria);
// 2. Persist the grid settings
//
GridSettingsPersister SavePersister = new GridSettingsPersister(ResultsGrid);
HttpCookie cookieResults = new HttpCookie("StoredSearchResults_" + cookieName);
cookieResults.Values["GridId"] = ResultsGrid.ID;
cookieResults.Values["GridSettings"] = SavePersister.SaveSettings();
cookieResults.Expires = DateTime.Now.AddDays(1d);
Response.Cookies.Add(cookieResults);
}
catch (Exception exception)
{
Logger.Write(exception);
}
}
protected void RestoreSearchCookie_Criteria(string cookieName)
{
try
{
HttpCookie cookieCriteria = Request.Cookies["StoredSearchCriteria_" + cookieName];
if (cookieCriteria != null)
{
foreach (string key in cookieCriteria.Values.AllKeys)
{
string value = cookieCriteria[key];
string[] ids = key.Split('>');
string parentId = ids[0];
string id = ids[1];
Control control = FindControl(parentId).FindControl(id);
Type type = control.GetType();
if (type == typeof(TextBox))
{
((TextBox)control).Text = value;
}
else if (type == typeof(DropDownList))
{
((DropDownList)control).SelectByValue(value);
}
else if (type == typeof(HiddenField))
{
((HiddenField)control).Value = value;
}
else if (type == typeof(RadioButton))
{
((RadioButton)control).Checked = Boolean.Parse(value);
}
else if (type == typeof(CheckBox))
{
((CheckBox)control).Checked = Boolean.Parse(value);
}
}
}
}
catch (Exception exception)
{
Logger.Write(exception);
}
}
protected void RestoreSearchCookie_Results(string cookieName)
{
try
{
HttpCookie cookieResults = Request.Cookies["StoredSearchResults_" + cookieName];
if (cookieResults != null)
{
string gridId = cookieResults.Values["GridId"];
string settings = cookieResults.Values["GridSettings"];
RadGrid grid = (RadGrid)FindControl(gridId);
GridSettingsPersister LoadPersister = new GridSettingsPersister(grid);
LoadPersister.LoadSettings(settings);
grid.Rebind();
}
}
catch (Exception exception)
{
Logger.Write(exception);
}
}
private void FindFormControls(List<Control> foundSofar, Control parent)
{
List<Type> types = new List<Type> { typeof(TextBox), typeof(DropDownList), typeof(RadioButton), typeof(CheckBox), typeof(HiddenField) };
foreach (Control control in parent.Controls)
{
if (types.Any(item => item == control.GetType()))
{
foundSofar.Add(control);
}
if (control.Controls.Count > 0)
{
this.FindFormControls(foundSofar, control); // Use recursion to find all descendants.
}
}
}