I use a System.Web.UI.WebControls.Menu to build and present a user menu. Loading the menu requires considerable database activity and takes about 1.4 seconds, so I am looking for ways to cache the menu across page turns. If I keep a SessionVariable["ThisMenu"] that contains the menu control, the value of ThisMenu is correct across page turns; however, I cannot set the actual control on the page successfully.
If I try this code, it compiles and executes, but nothing appears in the HTML output:
System.Web.UI.WebControls.Menu ctlMasterMenu = (System.Web.UI.WebControls.Menu)GetControl("ctlMasterMenu");
if (ctlMasterMenu != null)
{
if (ThisMenu != null)
{
ctlMasterMenu = ThisMenu;
}
else
{
LoadPageMenu((System.Web.UI.WebControls.Menu)ctlMasterMenu); // Sets ThisMenu
}
}
If I try this code, it executes, but as it adds a MenuItem to ctlMasterMenu, it removes the item from ThisMenu. The result is that after a few page turns, the menu is empty.
System.Web.UI.WebControls.Menu ctlMasterMenu = (System.Web.UI.WebControls.Menu)GetControl("ctlMasterMenu");
if (ctlMasterMenu != null)
{
if (ThisMenu != null)
{
List<MenuItem> items = new List<MenuItem>();
for (int i = 0; i < ThisMenu.Items.Count; i++)
{
items.Add(ThisMenu.Items[i]);
}
ctlMasterMenu.Items.Clear();
foreach (MenuItem item in items)
{
ctlMasterMenu.Items.Add(item); // Causes item to be removed from ThisMenu
}
}
else
{
LoadPageMenu((System.Web.UI.WebControls.Menu)ctlMasterMenu);
}
}
There must be a simple way that works.
Consider caching or reworking your database query. Caching the menus will likely result in storing additional data on the server or client via ViewState. The source of your menus is your data so you should start there.
Store the actual data that builds the menu in cache, and build the menu every time from this cached data. Disable viewstate to save on performance. Don't store the menu or menu items themselves.
Related
I'm developing an application with a menu which contains a list of buttons, when you click one of these buttons, another activity (the same activity with different image for each button) is opened showing an imageview. The problem is that when i click several times in different buttons (opening new images) the app crashes and i'm not able to solve it. Any help? Thanks.
That problem is because your are using a lot of images in your views and never clean the memory, then in one momento your don't have more memory for the new ones.
One form to resolve that problem is cleaning the memory always your destroy and activity.
You can override the next method in your activity for clean the memory.
#Override
public void unbindDrawables(View view) {
if (view.getBackground() != null) {
view.getBackground().setCallback(null);
}
if (view instanceof ViewGroup) {
for (int i = 0; i < ((ViewGroup) view).getChildCount(); i++) {
unbindDrawables(((ViewGroup) view).getChildAt(i));
}
((ViewGroup) view).removeAllViews();
}
}
that method review a view, in your case those views will be your ImageView and ImageButton.
Finally you need call this method in the method onDestroy() (need override that method too).
Summary
I'm having style issues when flipping master pages via a button event in asp.net 4.0. The new master switches, but the css from the old master remains. I don't understand how this could happen as the styles are defined within the head of the old master, and i can clearly see via the markup the new master is being displayed with whats supposed to be a totally different set of styles. Also, viewing source shows all the new css declarations in the head. How can i get this to "refresh" or "reload"?
Some details
I'm implementing a mobile version of my asp.net site. If a mobile device is detected i set a cookie and switch the master page in the preinit to a mobile friendly one. This works fine:
protected virtual void Page_PreInit(Object sender, EventArgs e)
{
if (IsMobile)
this.Page.MasterPageFile = "m-" + this.Page.MasterPageFile;
}
I have a "full site" button at the bottom that allows you to flip back and forth between the mobile and desktop view. When clicking it, i change the value in the cookie. Then when the page redirects to itself, the value is checked, and it gives the respective masterpage. This also "works", i can tell the right masterpage is rendering via markup. Except the styles from the mobile version remain even when the desktop master is being displayed. I did the redirect thinking it would prevent this.
// desktop/mobile site toggle button click event
protected void viewMobileButton_Click(Object sender, EventArgs e)
{
HttpCookie isMobileCookie = Cookies.snatchCookie("isMobile");
if (bool.Parse(isMobileCookie.Value))
Cookies.bakeCookie("isMobile", "false");
else
Cookies.bakeCookie("isMobile", "true");
Response.Redirect(Request.RawUrl);
}
This is the first time I've done anything like this, and not sure if i'm even going about it the right way, or how to debug from here. Thanks in advance for any help.
Edit
Ok, so i figured out it's related to the JQuery Mobile Scripts. JQuery Mobile has this way of tying pages together. I don't fully understand it, i think they use it for page transitions, and it's preventing my new CSS from registering. When i turn it off, my masterpage flips fine with css included. I'm looking into a way to turn off JQuery Mobile before my redirect. Note sure how though yet.
The problem ended up being related to JQuery Mobile AJAX for page-transitions. JQuery Mobile does not load the head of the document on additional page requests after the first.
So when i'd switch the mobile master to the desktop master, the head of the document wouldn't load to bring in my styles. There are a few way's this can be fixed:
This way just turns off AJAX altogether, and fixes the problem, but then you can't benefit from it:
<form data-ajax="false">
This is a way to do it problematically, but remind you, it will not work via an event after initialization of JQuery Mobile, so again you can't benefit from it:
$.mobile.ajaxEnabled = false;
The above two solutions i support could work if you redirected through a page first if you have to use an onclick event and an event handler.
A better solution is to add rel="external" to the link to tell JQM it's and outgoing link.
<a href="myself.com?mobile=true" rel="external" >
But because i couldn't run some code i wanted to in order to change the cookie, i had to pass a query string parameter, check it on the preinit, then set the cookie which my page also looks at on the preinit and flips the master.
Here's my full solution below in case someone is out there doing the exact same thing. Note because my website is using aliasing, i had to read Request.RawUrl and parse it myself since the Request.QueryString object did not contain the values i passed.
// reusable function that parses a string in standard query string format(foo=bar&dave=awesome) into a Dictionary collection of key/value pairs
// return the reference to the object, you have to assign it to a local un-instantiated name
// will accept a full url, or just a query string
protected Dictionary<string, string> parseQueryString(string url)
{
Dictionary<string, string> d = new Dictionary<string, string>();
if (!string.IsNullOrEmpty(url))
{
// if the string is still a full url vs just the query string
if (url.Contains("?"))
{
string[] urlArray = url.Split('?');
url = urlArray[1]; // snip the non query string business away
}
string[] paramArray = url.Split('&');
foreach (string param in paramArray)
{
if (param.Contains("="))
{
int index = param.IndexOf('=');
d.Add(param.Substring(0, index), param.Substring(++index));
}
}
}
return d;
}
Then i just use my dictionary object to evaluate and rebuild my url with the opposite mobile value, dynamically setting the href on the toggle link. Some code is obviosuly left out, but for perspective, base._iPage.QueryStringParams hold my dictionary object that was returned, and base._iPage.IsMobile is just a bool property i also have via the page interface i use, that all my pages, and user controls, ect, can talk to.
// get the left side fo the url, without querystrings
StringBuilder url = new StringBuilder(Request.RawUrl.Split('?')[0]);
// build link to self, preserving query strings, except flipping mobile value
if (base._iPage.QueryStringParams.Count != 0)
{
if (base._iPage.QueryStringParams.ContainsKey("mobile"))
{
// set to opposite of current
base._iPage.QueryStringParams["mobile"] = (!base._iPage.IsMobile).ToString();
}
int count = 0;
url.Append('?');
// loop through query string params, and add them back on
foreach (KeyValuePair<string, string> item in base._iPage.QueryStringParams)
{
count++;
url.Append(item.Key + "=" + item.Value + (count == base._iPage.QueryStringParams.Count ? "" : "&" ));
}
}
// assign rebuild url to href of toggle link
viewMobileButton.HRef = url.ToString();
}
Then on my pageinit this is where i actually check, first the quesry string, then the cookie, if neither of those are present, i run my mobile detection method, and set a cookie, and my interface bool property for easy access to conditionals that depends on it.
QueryStringParams = base.parseQueryString(Request.RawUrl);
if (QueryStringParams.ContainsKey("mobile") ? QueryStringParams["mobile"].ToLower().Equals("true") : false)
{
Cookies.bakeCookie("isMobile", "true"); // create a cookie
IsMobile = true;
}
else if (QueryStringParams.ContainsKey("mobile") ? QueryStringParams["mobile"].ToLower().Equals("false") : false)
{
Cookies.bakeCookie("isMobile", "false"); // create a cookie
IsMobile = false;
}
else
{
IsMobile = base.mobileDetection();
}
if (IsMobile)
this.Page.MasterPageFile = "m-" + this.Page.MasterPageFile;
}
I have a dropdown list that pulls data from template table. I have an Add button to insert new template. Add button will brings up jQuery popup to insert new values. There will be a save button to save the new data. On_Save_Click I enter the new data and close the popup.
Here is the proplem:
When I refresh the page, the page entering the values again. So, I get duplicate entries!
Question:
How can I avoid this issue? I check out Satckoverflow and Google, both they suggest to redirect to another page. I don't want to redirect the user to another page. How can I use the same form to avoid this issue? Please help.
You can use viewstate or session to indicate if data already inserted (button pressed).
Something like this:
private void OnbuttonAdd_click()
{
if(ViewState["DataInserted"] != "1")
{
...
// Add new entry...
...
if(data inserted successfully)
{
ViewState["DataInserted"] = "1";
}
}
}
Edit:
public bool DataInserted
{
get
{
if (HttpContext.Current.Session["DataInserted"] == null)
{
HttpContext.Current.Session["DataInserted"] = false;
}
bool? dataInserted = HttpContext.Current.Session["DataInserted"] as bool?;
return dataInserted.Value;
}
set
{
HttpContext.Current.Session["DataInserted"] = value;
}
}
...
private void OnbuttonAdd_click()
{
if(!DataInserted)
{
...
// Add new entry...
...
if(data inserted successfully)
{
DataInserted = true;
}
}
}
The simplest way is to use a post/redirect/get pattern.
Basically, the refresh action for page build with post requires to repost the data. Using this pattern, you will reload the whole page.
With ASP.Net, you have a simple alternative, use an UpdatePanel. This will refresh only part of the page using AJAX. As the page itself is still the result of a GET request, you can refresh the page. And as you use ASP.Net, it's quite easy to integrate.
Finally, you can use a home made AJAX refresh. A combination of jQuery, KnockOut and rest services (for example), can help you to avoid refreshing the full page in benefits of an ajax call.
There is some experience:
Disable Submit button on click (in client side by JavaScript).
change Session['issaved'] = true on save operation at server side and change it on new action to false.
use view state for pass parameters like RecordId (instead of QueryString) to clear on refresh page. i always pass parameter's with Session to new page, then at page load set
ViewState['aaa']=Session['aaa'] and clear Sessions.
...I hope be useful...
Do this it is very easy and effective
Intead of giving IsPostBack in the page load(),please provide inside the button click (To send or insert data)
Call the same page again after reseting all input values
protected void Btn_Reg_Click1(object sender, EventArgs e)
{
try
{
if (IsPostBack)
{
Registration_Save();
Send_Mail();
txtEmail.Text = "";
txtname.Text = "";
Response.Redirect("~/index.aspx");
}
}
catch (Exception) { }
}
You won't see any server messages after refreshing the page..
I thought this was straight forward, but i have a link button, and I do this in the click event:
myContainer.Controls.Add( new FileUpload());
I expect 1 new file control upload to be spawned in the container for each click, however, I always get 1. What do I need to do to have multiple file upload controls?
Since the control was added dynamically, it does not survive the postback. This means that you have to add the file upload (or any other dynamically added control) again in the preinit event to be able to have its values populated and to use it later on in the page life cycle.
Sounds like you are trying to be able to upload multiple files. You may want to add the file uploads with jQuery and use the Request.Files property to get them on the back-end.
I agree with Becuzz's answer. Try this, there are better ways to do it, but this might help as well:
Add this to the "Load" event of your page
if (!IsPostBack) {
Session["UploadControls"] = null;
}
if (Session["UploadControls"] != null) {
if (((List<Control>)Session["UploadControls"]).Count > 0) {
foreach ( ctrl in (List<Control>)Session["UploadControls"]) {
files.Controls.Add(ctrl);
}
}
}
And also add this to the PreInit portion of your page:
string ButtonID = Request.Form("__EVENTTARGET");
if (ButtonID == "Button1") {
FileUpload NewlyAdded = new FileUpload();
List<Control> allControls = new List<Control>();
if (Session["UploadControls"] != null) {
if (((List<Control>)Session["UploadControls"]).Count > 0) {
foreach ( ctrl in (List<Control>)Session["UploadControls"]) {
allControls.Add(ctrl);
//Add existing controls
}
}
}
if (!allControls.Contains(NewlyAdded)) {
allControls.Add(NewlyAdded);
}
Session["UploadControls"] = allControls;
}
And add this to your HTML. This can be anything of course:
<div id="files" runat="server">
</div>
I use the "__EVENTTARGET" value to know what caused the postback, so that you don't get unwanted Upload controls.
Good luck, and hopefully this helps.
Hanlet
I'm doing a menu that loads levels dynamicly, when you click on a item the next level is loaded asynchronously. For each menu item I have a user control. Every user control is declared in its parent, for example, the "secondlevelcontrol" has the reference to "thirdlevelcontrol".
With this level of nesting, I want to manage the asynchronous calls on every user control so, when the first level is loaded the javascript to load the second is loaded too. When the second level is loaded the javascript to load the third is loaded too.
To do asynchronous calls I'm implementing ICallbackEventHandler interface. As you can see in the examples, controls are added to the page as plain html. The method "ProcessOnLoadEvent" executes all lines of the "OnLoad" event of the user control.
An example of the implementation is this for the user control of fourth level:
public string GetCallbackResult()
{
return _callbackRendering;
}
public void RaiseCallbackEvent(string itemId)
{
var id = Int32.Parse(itemId);
var menu = new LateralMenu();
var currentChildren = menu.GetNodesById(id, 1);
var ctrl = this.Page.LoadControl(USER_CONTROL_FIVE_LEVEL_RELATIVE_PATH) as LeftSideFifthLevel;
ctrl.Items = currentChildren.Children;
ctrl.ProcessOnLoadEvent();
_callbackRendering = ctrl.GetHtml();
}
And this is the code for the fifth level user control:
public void ProcessOnLoadEvent()
{
EnsureChildControls();
if (null != RepeaterMenu)
{
SettingCallbackReference();
Visible = null != Items && 0 < Items.Count;
if (null != Items && 0 < Items.Count)
{
RepeaterMenu.DataSource = Items;
RepeaterMenu.DataBind();
}
}
}
public void RaiseCallbackEvent(string itemId)
{
var id = Int32.Parse(itemId);
var menu = new LateralMenu();
var currentChildren = menu.GetNodesById(id, 1);
var ctrl = this.Page.LoadControl(USER_CONTROL_SIX_LEVEL_RELATIVE_PATH) as LeftSideSixthLevel;
ctrl.Items = currentChildren.Children;
ctrl.ProcessOnLoadEvent();
_callbackRendering = ctrl.GetHtml();
}
public void SettingCallbackReference()
{
var cm = this.Page.ClientScript;
var cbRef = cm.GetCallbackEventReference(this, "itemId", "AnchorLevel5_OnClick_Callback", "ctx");
var cbScript = "function AnchorLevel5_OnClick(itemId, ctx){ new Menu().empty(ctx); " + cbRef + "; }";
cbScript += "function AnchorLevel5_OnClick_Callback(htmlText, ctx){ new Menu().render(htmlText, ctx); }";
cm.RegisterClientScriptBlock(this.GetType(), "CallServer", cbScript, true);
}
My problem is that levels beyond second level never work because the javascript associated with the user control ("SettingCallbackReference" method) has no html to put on the page.
Is there any way to create some user controls created dynamicly that implements ICallbackEventHandler interface that add new user controls to the page? Or, Am I doing something wrong and this is not the right way to implement this behaviour?
Thanks!!!
I suspect that you are probably going about this the wrong way. Take a look at the answer to this question: How to lazy load Infragistics UltraWebTree control?
This question was specifically about lazy-loading a tree view, but the same principles apply for lazy loading menu items. Follow these steps:
On first page load, render the top level menu
Include a function on the page that makes an ajax call to the server with the
parent id and retuns the next level items for that parent (getNodes in my example)
Bind this function to the click event of the top level menu items (that have sub items)
In the success handler of the ajax call, inject the returned menu items below
the parent and bind the same function to the click event of these items only.
On callback, be careful not to bind the function to the click event of ALL menu items, because then you will end up getting the function bound multiple times to the top level items and called multiple times. Just bind to the returned items.
Also, you need some way of determining that an item's sub items have already been loaded. That is what the following line in my example was for, but you might need something slightly different:
if (jQuery(nodesDiv).text() == 'Loading...') {
I used jQuery because it is the most concise, but you culd do this in pure js - I wouldn't recommend it.