Perhaps my previous question on output caching output caching was too complex.
Let's simplify.
How can I get the final, "ready for sending" rendered HTML from a page (or control) event in ASP.Net? I assume that this will be the same content that will be used for the output cache, so could be queried to find out what is about to be placed into the cache.
Code copied from:
http://aspcode.net/Last-second-HTML-changes-in-your-ASPNET-page.aspx
protected override void Render(HtmlTextWriter writer)
{
using(System.IO.MemoryStream msOur = new System.IO.MemoryStream())
{
using(System.IO.StreamWriter swOur = new System.IO.StreamWriter(msOur))
{
HtmlTextWriter ourWriter = new HtmlTextWriter(swOur);
base.Render(ourWriter);
ourWriter.Flush();
msOur.Position = 0;
using(System.IO.StreamReader oReader = new System.IO.StreamReader(msOur))
{
string sTxt = oReader.ReadToEnd();
Response.Write(sTxt);
oReader.Close();
}
}
}
}
Related
I created a master report file. Then I created subreport file. Is there a way to put xml code of the subreport file as a report source ?
Override OnBeforePrint method and go through XtraReportBase.Controls property tree to find XRSubreport. As described here you can use DataSet and its DataSet.ReadXml method:
protected override void OnBeforePrint(PrintEventArgs e)
{
base.OnBeforePrint(e);
//Get your xml here
var dataSet = new DataSet();
using (var reader = new StringReader(xml))
dataSet.ReadXml(reader);
SetSubReportXML(this, dataSet);
}
private void SetSubReportXML(XRControl xrControl, DataSet dataSet)
{
foreach (XRControl xrControlChild in xrControl.Controls)
{
var subReport = xrControlChild as XRSubreport;
if (subReport != null)
{
//Set your xml here
subReport.ReportSource.DataSource = dataSet;
subReport.ReportSource.DataMember = this.DataMember;
SetSubReportXML(subReport.ReportSource, dataSet);
}
SetSubReportXML(xrControlChild, dataSet);
}
}
I am trying to create a custom control and the render method is shown below.
I get an "Object reference not set to an instance of an object" error on the bulletList.RenderControl(Writer); line.
Any ideas?
protected override void Render(HtmlTextWriter Writer)
{
if (TermSetList != null && TermSetList.Count > 0)
{
BulletedList bulletList = new BulletedList();
bulletList.Click += new BulletedListEventHandler(BulletListItem_Click);
bulletList.DisplayMode = BulletedListDisplayMode.LinkButton;
bulletList.CssClass = "tabs";
foreach (KeyValuePair<String, String> item in TermSetList)
{
ListItem listItem = new ListItem();
listItem.Text = item.Key;
listItem.Value = item.Value;
bulletList.Items.Add(listItem);
}
if (!this.Page.IsPostBack)
{
bulletList.Items[0].Selected = true;
}
bulletList.RenderControl(Writer);
base.Render(Writer);
}
}
You generally do not want to add controls during render. How your currently doing this will ensure that your click handler never gets called.
My guess as to why you are getting the error is that the control has not been added to the controls collection.
My suggestion is to move the logic to an earlier event, perhaps onload, you would not need to override the Render method then.
I am developing a sharepoint 2007 web part that uses custom properties. Here is one:
[Personalizable(PersonalizationScope.User), WebDisplayName("Policy Update List Name")]
[WebDescription("The name of the SharePoint List that records all the policy updates.\n Default value is Policy Updates Record.")]
public string PolicyUpdateLogName
{
get { return _PolicyUpdateLogName == null ? "Policy Updates Record" : _PolicyUpdateLogName; }
set { _PolicyUpdateLogName = value; }
}
The properties work fine except that the changes are not reflected in the web part until you leave the page and navigate back (or just click on the home page link). Simply refreshing the page doesn't work, which makes me think it has something to do with PostBacks.
My current theory is that the ViewState is not loading postback data early enough for the changes to take effect. At the very least, the ViewState is involved somehow with the issue.
Thanks,
Michael
Here is more relevant code:
protected override void CreateChildControls()
{
InitGlobalVariables();
FetchPolicyUpdateLog_SPList();
// This function returns true if the settings are formatted correctly
if (CheckWebPartSettingsIntegrity())
{
InitListBoxControls();
InitLayoutTable();
this.Controls.Add(layoutTable);
LoadPoliciesListBox();
}
base.CreateChildControls();
}
...
protected void InitGlobalVariables()
{
this.Title = "Employee Activity Tracker for " + PolicyUpdateLogName;
policyColumnHeader = new Literal();
confirmedColumnHeader = new Literal();
pendingColumnHeader = new Literal();
employeesForPolicy = new List<SPUser>();
confirmedEmployees = new List<SPUser>();
pendingEmployees = new List<SPUser>();
}
...
// uses the PolicyUpdateLogName custom property to load that List from Sharepoint
private void FetchPolicyUpdateLog_SPList()
{
site = new SPSite(siteURL);
policyUpdateLog_SPList = site.OpenWeb().GetList("/Lists/" + PolicyUpdateLogName);
}
...
protected void InitListBoxControls()
{
// Init ListBoxes
policies_ListBox = new ListBox(); // This box stores the policies from the List we loaded from SharePoint
confirmedEmployees_ListBox = new ListBox();
pendingEmployees_ListBox = new ListBox();
// Postback & ViewState
policies_ListBox.AutoPostBack = true;
policies_ListBox.SelectedIndexChanged += new EventHandler(OnSelectedPolicyChanged);
confirmedEmployees_ListBox.EnableViewState = false;
pendingEmployees_ListBox.EnableViewState = false;
}
...
private void LoadPoliciesListBox()
{
foreach (SPListItem policyUpdate in policyUpdateLog_SPList.Items)
{
// Checking for duplicates before adding.
bool itemExists = false;
foreach (ListItem item in policies_ListBox.Items)
if (item.Text.Equals(policyUpdate.Title))
{
itemExists = true;
break;
}
if (!itemExists)
policies_ListBox.Items.Add(new ListItem(policyUpdate.Title));
}
}
Do some reading up on the Sharepoint web part life cycle. Properties are not updated until the OnPreRender event.
while the method we use in Substitution control should return strings, so how is it possible to use a donut caching in web forms on a server control which should be rendered server side?
for example Loginview control?
UPDATE
This is now a fully working example. There a few things happening here:
Use the call back of a substitution control to render the output of the usercontrol you need.
Use a custom page class that overrides the VerifyRenderingInServerForm and EnableEventValidation to load the control in order to prevent errors from being thrown when the usercontrol contains server controls that require a form tag or event validation.
Here's the markup:
<asp:Substitution runat="server" methodname="GetCustomersByCountry" />
Here's the callback
public string GetCustomersByCountry(string country)
{
CustomerCollection customers = DataContext.GetCustomersByCountry(country);
if (customers.Count > 0)
//RenderView returns the rendered HTML in the context of the callback
return ViewManager.RenderView("customers.ascx", customers);
else
return ViewManager.RenderView("nocustomersfound.ascx");
}
Here's the helper class to render the user control
public class ViewManager
{
private class PageForRenderingUserControl : Page
{
public override void VerifyRenderingInServerForm(Control control)
{ /* Do nothing */ }
public override bool EnableEventValidation
{
get { return false; }
set { /* Do nothing */}
}
}
public static string RenderView(string path, object data)
{
PageForRenderingUserControl pageHolder = new PageForUserControlRendering();
UserControl viewControl = (UserControl) pageHolder.LoadControl(path);
if (data != null)
{
Type viewControlType = viewControl.GetType();
FieldInfo field = viewControlType.GetField("Data");
if (field != null)
{
field.SetValue(viewControl, data);
}
else
{
throw new Exception("ViewFile: " + path + "has no data property");
}
}
pageHolder.Controls.Add(viewControl);
StringWriter result = new StringWriter();
HttpContext.Current.Server.Execute(pageHolder, result, false);
return result.ToString();
}
}
See these related questions:
Turn off page-level caching in a
user control
UserControl’s RenderControl is
asking for a form tag in (C#
.NET)
One thing Micah's answer left out is that the substitution function must be static, accept a HttpContext parameter, and return a string. See this msdn page for more info.
I've also extended Micah's helper class to be a little more flexible.
Markup
<asp:Substitution ID="Substitution1" MethodName="myFunction" runat="server" />
Implemenation
public static string myFunction(HttpContext httpContext){
ViewManager vm = new ViewManager();
//example using a Button control
Button b = new Button();
b.Text = "click me"; //we can set properties like this
//we can also set properties with a Dictionary Collection
Dictionary<string,object> data = new Dictionary<string,object>();
data.add("Visible",true);
String s = vm.RenderView(b,data); //don't do anything (just for example)
//we can also use this class for UserControls
UserControl myControl = vm.GetUserControl("~mypath");
data.clear();
data.add("myProp","some value");
return vm.RenderView(myControl,data); //return for Substitution control
}
Class
using System.IO;
using System.ComponentModel;
public class ViewManager
{
private PageForRenderingUserControl pageHolder;
public ViewManager()
{
pageHolder = new PageForRenderingUserControl();
}
public UserControl GetUserControl(string path)
{
return (UserControl)pageHolder.LoadControl(path);
}
public string RenderView(Control viewControl, Dictionary<string, object> data)
{
pageHolder.Controls.Clear();
//Dim viewControl As UserControl = DirectCast(pageHolder.LoadControl(Path), UserControl)
if (data != null) {
Type viewControlType = viewControl.GetType();
dynamic properties = TypeDescriptor.GetProperties(viewControl);
foreach (string x in data.Keys) {
if ((properties.Item(x) != null)) {
properties.Item(x).SetValue(viewControl, data[x]);
}
}
}
pageHolder.Controls.Add(viewControl);
StringWriter result = new StringWriter();
HttpContext.Current.Server.Execute(pageHolder, result, false);
return result.ToString();
}
private class PageForRenderingUserControl : Page
{
public override void VerifyRenderingInServerForm(Control control)
{
// Do nothing
}
public override bool EnableEventValidation {
get { return false; }
// Do nothing
set { }
}
}
}
Thanks again to Micah for the code
I'm fairly certain you can't do this - the Substitution control will only allow you to insert a string into an outputcached page.
This makes sense if you think about the whole output of a server control, which could be a <table> that'll disrupt all your carefully crafted markup and/or something that requires a load of <script> injected into the page - whereas injecting a single string is something that's relatively straightforward.
I have an asp.net textbox like this:
<asp:TextBox ID="PINPad" runat="server" Columns="6" MaxLength="4"
CssClass="PINTextClass"></asp:TextBox>
It is, as you might have guessed, the text box from an on screen PIN pad. Javascript fills in the values. The page is posted back every five seconds (using an update panel if that matters) to update various other unrelated items on the screen. This works just fine.
However, when I convert it to a password text box, like this:
<asp:TextBox ID="PINPad" runat="server" Columns="6" MaxLength="4"
CssClass="PINTextClass" TextMode="Password"></asp:TextBox>
Then whenever the page posts back, the text box is cleared out on the screen and the textbox is empty (though during the timer event, the value does make it back to the server.)
Any suggestions how to fix this, so that it retains its value during postback?
As a security feature, ASP.NET tries to disallow you from sending the password value back to the client. If you're okay with the security issues (i.e. it's either not really secure information or you're sure that the connection is secure), you can manually set the "value" attribute of the control, rather than using its Text property. It might look something like this:
this.PINPad.Attributes.Add("value", this.PINPad.Text);
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
{
if (!(String.IsNullOrEmpty(txtPwd.Text.Trim())))
{
txtPwd.Attributes["value"]= txtPwd.Text;
}
if (!(String.IsNullOrEmpty(txtConfirmPwd.Text.Trim())))
{
txtConfirmPwd.Attributes["value"] = txtConfirmPwd.Text;
}
}
}
here is another way to do it:-
using System;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebControlLibrary
{
public class PWDTextBox : TextBox
{
public PWDTextBox()
{
this.TextMode = TextBoxMode.Password;
}
public string Password
{
get
{
string val = (string)ViewState["pwd"];
if (string.IsNullOrEmpty(val))
{
return "";
}
else
{
return val;
}
}
set
{
ViewState["pwd"] = value;
}
}
public override string Text
{
get
{
return Password;
}
set
{
Password = value;
}
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
this.Text = Password;
}
protected override void AddAttributesToRender(HtmlTextWriter writer)
{
base.AddAttributesToRender(writer);
writer.AddAttribute(HtmlTextWriterAttribute.Value, this.Password);
}
}
}
The problem of losing the password in the postback can be avoid making use of Asynchronous JavaScript calls, lets describe a typical scenario for a Login page:
Lets say we have a Login page which allows the user to change the language of its labels when the user choose a language with a dropdownlist
a solution would be to invoke selectedIndexChanged event of the dropdownlist, make a postback which goes to the server and picks up the labels in the chosen language.
in this scenario the field password will be lost due to the security feature of ASP.NET which makes passwords fields not persisted between a postbacks.
This scenario can be solved if the postback is avoided making use of Asynchronous JavaScript Technology and XML (Ajax) calls.
Add a javascript function which will be invoked from the dropdownlist control, in this case this function is assigned to the Command property of the dropdownlist in code behind:
function ValueChanged(div)
{
var table = div.getElementsByTagName("table");
if (table && table.length > 0)
{
var t = table[0].getAttribute('type');
if (t != null && (t == "DropDown"))
{
var inputs = div.getElementsByTagName("input");
if (inputs && inputs.length == 2)
{
{
Translate(inputs[1].value);
}
}
}
}
}
The Translate function takes as parameter the selected option language in the dropdown control and performs the asynchronous call as shown bellow.
function Translate(lang)
{
var request = null;
if (window.XMLHttpRequest)
{
request = new XMLHttpRequest();
if (request.overrideMimeType)
{
request.overrideMimeType('text/xml');
}
}
else if (window.ActiveXObject)
{
request = new ActiveXObject("Msxml2.XMLHTTP");
}
if (request == null)
{
return;
}
var url = "GetLoginTranslations.aspx";
request.open('GET', url +'?lang=' + lang, true);
request.setRequestHeader("Cache-Control", "no-cache");
request.setRequestHeader("Pragma", "no-cache");
request.setRequestHeader("If-Modified-Since", "Sat, 1 Jan 2000 00:00:00 GMT");
request.onreadystatechange = function () { TranslateLabels(request); };
request.send(null);
}
the function Translate shown above performs the call and get the results in the specified .aspx page (in this case "GetLoginTranslations.aspx")
when the request is completed and the request.onreadystatechange is set to the function TranslateLabels this function will be executed.
on this way the postback is not executed as before in the event onSelectedIndexChanged of the dropdownlist control.
the TranslateLabels function would look something like :
function TranslateLabels(request)
{
if (request.readyState == 4)
{
if (request.status == 200)
{
if (request.responseXML)
{
var objRoot = request.responseXML.documentElement;
if (objRoot)
{
if (objRoot.nodeName == "strings")
{
for (var i = 0; i < objRoot.childNodes.length; i++)
{
var node = objRoot.childNodes[i];
var elem;
switch (node.getAttribute("id"))
{
case "lbl_login":
elem = document.getElementById("lbl_login");
if (elem)
elem.innerHTML = node.firstChild.nodeValue;
break;
}
///....
}
}
}
}
}
}
the request.responseXML contains the XML built in the page GetLoginTranslations.aspx and the structure of this XML is defined there.
the Page_Load() event in the GetLoginTranslations.aspx should look like:
protected void Page_Load(object sender, EventArgs e)
{
if (Request["lang"] != null)
strLang = Request["lang"];
//init response
Response.Clear();
Response.Cache.SetExpires(DateTime.Now);
Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetValidUntilExpires(true);
Response.ContentType = "application/xml";
Response.Charset = "utf-8";
XmlTextWriter xml = new XmlTextWriter(Response.OutputStream, System.Text.Encoding.UTF8)
{
Formatting = Formatting.None
};
xml.WriteStartDocument();
xml.WriteStartElement("strings");
xml.WriteStartElement("string");
xml.WriteAttributeString("id", "lbl_login");
xml.WriteString(GetTranslation("label_login", strLang));
xml.WriteEndElement();
// ... the other labels
xml.WriteEndElement(); //</strings>
xml.Close();
}
Some other considerations:
set the the property AutoPostback of the dropdownlist to false.
Happens both for view-model properties named 'Password' and 'PIN'. You can bypass the behavior by defining those as:
string Password ;
... rather than:
string Password { get; set; }
If you do so, features such the 'LabelFor' macro displaying 'DisplayAttribute.Name' no longer works, so you'd have to define those directly in the HTML.
Or you can simply name the fields something other than 'Password' or 'PIN'.